BE417475A - - Google Patents

Description

       

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  Improvements to telephone systems.



   The present invention relates to telephone systems in general, it relates more particularly to telephone systems comprising a main office and an annexed private office.



   The main object of the invention is to provide new and improved circuits for application to an annex private office to enable the various service characteristics required of such an office to be more efficiently given.
A complementary object can be cited, it is that which provides new and improved circuits to allow satisfactory service in a private office.

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 annex composed of several unitary offices.
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  General description E !! ± ¯gE
In order to describe the invention, we thought we were doing the right thing by applying its characteristics to a given installation, by way of example, in the case chosen the office consists of two switches and a satellite interconnected by junction circuits. The annex office is also interconnected with the central public office by the intermediary of trunk circuits going from each of the private switches to the public office and trunk circuits coming from the public office to the annex office as shown in fig. 1 of the annexed plans, it is also interconnected with other annexed offices and it is linked to interurban lines.



   Among the 52 figures of the annexed plans, 1 is a schematic map showing a central public office and the relative position of the unit offices of the annex office; figs. 2, 3, 4 and 5 form a junction diagram showing the various relationships between the various circuits and groups of selectors of the annex office which includes several switches. figs. 6 to 51 are circuits, finally FIG. 52 gives an assembly diagram of FIGS. é to 48 for ease of understanding.



   Referring to fig. 1 it must be admitted that the public central office, shown above the annex office, can be a complex central office made up of several central offices, likewise it can be of the manual or automatic type. In the current case, described below, the public office will be considered as a complex automatic office.



   The annex office consists of offices 9 and 8 which can be considered as main offices and an office 86 which is a satellite office of office 8.

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   In addition to the annex office comprising several offices, the system which will be described includes other annex offices located at a certain distance from that which is represented and which are in turn linked to other central public offices. The annex office which is shown on the plan is interconnected with these remote annex offices by means of junction circuits operated in both directions (I.B.X.) such as that associated with the LC4 line circuit of figs. 2 and 13.



   In the annex office also terminate interurban lines operated in the two suns and which come from a distant interurban office, such a line (TL) is associated with the circuit of line LC3 of fig. 2 and 12.



   Traffic between offices 9 and 8 flows. through jonc-tien circuits operated one in one direction and the other in both directions, they are shown on the plan in Tl to T3, the traffic between the office 8 and its satellite 86 borrows identical junction circuits, they are shown on the plan in T4 to T6. As will be explained later and as shown in other plans the traffic between office 9 and satellite 86 flows through office 8 which '-, this point of view plays the role of a tandem office.



   Calls from the three branch offices and destined for the public office are routed through trunk circuits passing directly from the respective offices to the central public office. Among the junction circuits the outgoing circuits OT1, OT2 and OT3 are shown in fig. 1.



   All calls arriving from the public office to the annex office are routed to the requested line by means of automatic switches, from an operator's table located in office 9. For this reason, all the junction circuits coming from the public office to the annexed office lead to office 9. This is represented by the incoming junction circuit IT in fig. 1.



   Note that the capacity of the annex office as

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 it is represented in fig. 1 is approximately 1300 lines and that office 9 serves 900 of those lines, office 8: 300, and satellite office 86: 100.



   Referring more particularly to FIGS. 2 and 3 it can be seen that the office 9 forming part of the annex office is shown in a dotted rectangle, the office 8 is shown in the rectangle of FIG. 4 and the satellite desk 86 is shown in the rectangle of FIG. 5, the public office (P.E.) is represented above the dotted lines crossing the figs. 2,3, 4 or 5 towards the top.



   As indicated by the number 18 associated with the junction circuit IT, this one is a junction circuit of a group of 18. Similarly the outgoing junction circuit OT1 is one of the eighteen junction circuits leaving the office 9 and leading to public office. In addition, the junction circuits OT2 and OT3 leaving offices 8 and 86 respectively represent a junction circuit of a group of ten and of a group of two. It will be understood that in each case the number of trunk circuits is that which has been calculated to enable the estimated traffic to flow.



   Cn will further note that the trunk T3 is part of a group of 36 trunk circuits operated in a single direction which carry traffic from office 9 to office 8; the junction circuit Tl is part of a. a group of 12 trunks operated in a single direction that carry traffic from office 8 to office 9; the trunk T2 is part of a group of 6 trunk circuits operated in both directions which carry traffic
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 cl, '-Lin office to the other indi: f3renr.: ent.



   Between office C and satellite 86, the trunk T6 operated in one direction flows traffic from office 8 to satellite office 86; one-way operated trunk T4 handles office 86 traffic

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 towards office 8 and the 3 trunk circuits represented by the trunk circuit T5 operated in both directions flows the traffic from one office to the other indifferently.



   Among the 1300 subscriber lines those of stations A1 to A4 are shown in FIGS. 3, 4 and 5, their respective numbers are: 91225, Q225, 8225, 8625. Each of the subscriber lines terminates in a preselector of the well known plunger type. The LS2 and LS3 preselectors, for example, are assigned to the lines of sets A1 and A2 in office 9.



   Office 9.



   The primary preselectors of office 9 have access to the primary selectors through secondary rotary preselectors, one of which is represented in SLS.



   One of the primary selectors accessible to the secondary SLS preselector is the primary selector FS5. This selector as well as the other selectors, finders and connectors is of the well known two movement type having the bank contacts arranged in horizontal rows or levels. The FS5 selector represents one of the selectors to which subscriber lines have access through primary and secondary pre-readers.



   To make possible the application of a universal numbering of the subscribers of the annex office (so that the number of the subscriber is identical to itself whatever the office from or from the call) the primary selector FS5 is designed to absorb the first digit emitted when it is the number 9. This characteristic has been indicated on the plan by placing the number 9 in the rectangle representing the primary selector FS5. The same characteristic is indicated in each of the DCS and FS1 to FS4 selectors while the number 9 placed in each of the rectangles representing

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 the arrival selectors IS1 and IS2 indicate that these selectors are entered by junctions coming from the ninth level of the preceding selectors (in office 8).



   Among the 10 levels of the primary selector FS5, the first six are used for the flow of traffic to the lines of the subscribers of the local office 9; the seventh level is used to route calls to the operator position when the number 97 is dialed, the eighth level is used to route calls to office 8, the ninth level used after absorption of the first digit 9 is used to direct calls to remote branch offices through special connectors such as BO; finally the tenth level, is used for sending calls to the public office through outgoing trunk circuits such as OT1.



   Among the six levels of the primary selector FS5 which are intended for establishing these communications to the local lines, levels 2 to 6 are reserved for groups of connectors 92 to 96. Among these groups of connectors, group 92 is represented by the connector. Iccal LCC2 which is one of the connectors in a group of around 10.



   As five hundred of the 900 lines in the office are served by levels 2 to 6 of the FS5 selector, the remaining 4CO lines must be reached through the first level of the FS5 selector. In order to extend the first level of primary selectors so as to allow four groups of 100 lines to be reached, a group of secondary selectors represented by the secondary selector SES, is reached when the digits are sent? and 1 (the number 9 being absorbed). These secondary selectors have access through their levels 2 to 5 to groups 912 to 915.

   The connectors of group 912 are represented by the local connector LCCl. The necessary introduction of secondary selectors

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 such as SES requires that four of the groups of 100 subscriber lines have five-digit numbers while five groups of 100 lines will have only four-digit numbers, for example the numbers assigned to sets A1 and A2 are: 91225 and 9225.



   Table 1: .. four operator positions shown in fig. 2 is intended primarily to serve calls coming from the public office through the 18 incoming trunk circuits, one of which is represented by IT.



   The operator's table and the automatic equipment associated with it are generally identical to the equipment described in Belgian Patent No. 412,533. A special feature of this type of table resides in the fact that the operator has connection circuits which terminate in automatic switches instead of cords terminating at manual switch plugs. This is shown in fig. 2, where the researcherFl connected to the primary selector FS1, represents one of the connection circuits of. position 1 and where researchers
F2, F3 and F4 connected to the primary selectors FS2, FS3 and FS4 represent connection circuits of positions 2, 3 and 4; in the system shown there are nine identical circuits for each operator position.

   The arrangement is such that when an operator is ready to accept a call and the conversation key of the connection circuit is actuated, the searcher of this connection circuit is ready to seek. dear the calling line which can then be extended by the associated primary selector.



   In addition the individual connection circuits are simplified as much as possible at the expense of the equipment of the position which is common to the nine connection circuits of this position.



   The junctions to the other annexed offices which are supposed to be at. number of 25 are represented by a

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 only line operated in the soft directions, I.B.X., ending in the LC4 line circuit, one line circuit being provided for each of the I.B.X. junctions. I.B.X. are accessible by researchers such as F1 to F4 through the second, third and fourth levels thereof.



   The fifth level of the searchers serves the interurban lines whose number is equal to 9. Each interurban line TL terminates in a line circuit such as LC3 through which it is reached by the searchers.



   The 18 trunk circuits coming from the public office are served by the sixth and seventh levels of researchers, there is a line circuit such as LC2 interposed between each trunk circuit and the researchers' benches.



   The eighth level of the seekers serves the incoming junctions from the seventh level of the primary selectors through individual circuits such as LUI, while the ninth and tenth levels are unused at this time.



   In addition to the above, it will be noted that the junctions coming from the first level of the researchers extend up to calls only to selectors / deferred, one of which is the DOS selector. The purpose of this arrangement will be explained later.



   In order to allow the operators of the 4-position table to quickly establish communications, a group of transceivers of which RS is one of them has been provided.



  In order to control these transceivers and to be able to associate them with connection circuits to which they must return the received pulses, each operator has two transmission circuits, those in position 1 are represented by SL1 and SL2. . The keys of numbers in the operator position can be connected indifferently to one or the other of the two circuits, the choice of this being automatic as will be seen. further.

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   The transmission circuit 1 is associated with the finder of the connection circuit LFl, the latter has access to the nine connection circuits of position 1. The transmitter selector SS1, associated with the transmission circuit SL1 has access to the RS transceiver and other transceivers, all of which are intended for common use by all attendants.



   The transmission circuit SL2 is likewise provided with the connection circuit finder LF2 and the transmitter selector SS2.



   In general, all selectors in office 9 (except secondary selectors such as SES) have their bank contact levels assigned in the same way as that of primary subscriber selectors which was discussed previously. for the primary selector FS5. There are a few differences, however, which will be pointed out now. All primary selectors and incoming selectors have their first six levels of bank contacts connected identically for establishing communications to local subscriber lines.

   The seventh level is not used in the primary attendant selectors FS1 through FS4 and in the DCS delayed call selector. This is for the reason that the seventh level gives access to the operator table and in no case will a call be sent to the table via these selectors since they can only be reached precisely at the start of the table. -this.



   The eighth level of the incoming ISI and IS2 selectors is / used because this level serves the outgoing trunk circuits to office 8 while the ISI and IS2 selectors are incoming selectors accessible only from office 8.



   With regard to the ninth level, the subscriber selectors FS5, ISl and IS2 have access to the connectors of the group
99, of which the branch office connector BC is an example, while the operator selectors DCS and FS1-FS4 have access through the ninth level to the trunk connectors (such as TC) of group 99.

   By this provision

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 when the number 99 is sent by a subscriber, a selector such as BC is put into service while if the number 99 is sent from one of the operator positions a long distance connector such as TC is put into service because the multiple of the ninth level is divided into two parts, one for each of the two classes of selectors. One of the reasons for adopting this arrangement is that the TC trunk connector has been specially designed to work with the circuits used in case. a communication is established through the operator table, while the BC connector is particularly suitable for communications from a subscriber.



  Additionally, trunk lines, such as that associated with LC3 line circuit, are only accessible from TC trunk connectors. This provision is made so that the subscriber who wishes to issue a. long distance call on one of these junctions is obliged to put in advance in communication with the operator of the annex office (by sending the number 97).



   With regard to the tenth level of the selectors, the selectors FS1 to FS4 cannot use this one because it is necessary that the operators are not able to extend to the public office a long distance communication or a call coming from an annex office. distant; subscribers to remote branch offices being obliged to call their own public office. The ISI and IS2 selectors do not use the tenth level because they are arrival selectors from office 8 where. direct junction circuits to the public office are planned.

   Delayed call selectors such as DCs, however, have access through the tenth level to trunk circuits such as CT1 outgoing to the public office. This is intended to allow the operator to establish a delayed communication between a line in the public office and a line in the adjoining office when requested.



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Arrangements have been made for a subscriber of the side office to be able to obtain the local transfer service while in conversation with a subscriber of the public office.



   If it is an incoming call, the subscriber of the annex office obtains the transfer service through the connector, if the call is outgoing this same subscriber obtains the transfer service through the departure repeater. For example, the local connectors LOC1 and LOC2 of the office. 9 are provided with preselectors LS4 and LS5, respectively, which have access, 1.through the secondary preselectors, to primary selectors such as Fs5, while the preselector LS1 is associated with the start repeater OR1 in a manner identical. Temporary connections can be established via the transfer preselectors to other lines of the annex office while the link to the public office is blocked as will be described in detail below.



   It will be noted that the junction circuit T3 from office 9 to office 8 is accessible via the eighth level of the selectors through the repeater R2 while the junction circuit T2, operated in both directions and connecting the desks 8 and 9, normally extends through repeater R1 to the incoming selector
IS2, but can be entered via the eighth level of the selectors through the repeater R1.

   As each junction circuit operated in both directions is provided with dual equipment and is therefore more expensive than a junction circuit operated in one direction only, the arrangement of the graded multiple is used so that one can be sure that a trunk operated in both directions will not be put into service until all trunk circuits operated in one direction have been tested and found to be occupied. From this point of view a junction circuit operated in both directions can be considered as a junction circuit.

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 As it is already known to carry the excess traffic, it is made common to a greater number of selectors than a trunk circuit operated in one direction only.



    'Office 8.



   With particular reference to desk 8 of FIG. 4 it can be seen that the arrival selectors IS3 and IS4 are associated with the junction circuits T3 and T2 respectively while the arrival selectors IS5 and IS6 are likewise associated with the junction circuits T4 and T5, respectively, to route the traffic entering office 8 from satellite 86. The primary selector FS6, like the primary selector FS5 in office 9, handles traffic from local subscribers. The subscriber of set A3 for example (N 8225) obtains the connection with the primary selector FS6 through his preselector LS7 which itself has access to other similar primary selectors.



   The three groups of 100 subscriber lines are accessible from levels 2, 3 and 4 of the selectors, connector L06, representing the connectors of group 82, accessible from the second level of the selectors. The primary selector FS6 similar to the primary selector FS5 of the office 9 is provided and equipped to return to the rest position and therefore to absorb the first digit emitted when this is the characteristic digit of the local office. This is indicated in selector FS6 by the number 9 placed in the rectangle representing the selector mechanism. The number 8 is also placed in the rectangles representing the arrival selectors IS3 and IS4 and to indicate that these selectors are activated when the number 8 is transmitted in the office from which they are accessible.



   The LS6 and LS8 preselectors, associated with the outgoing repeater OR2 and the local connector LOC3 respectively, are transfer preselectors provided for the reason that was

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 exposed for the LS4 and LS5 preselectors of office 9.



   The arrival selectors IS5 and IS6 which are associated with the trunk circuits T4 and T5 for the routing of calls entering the office 8 and. coming from satellite 86 are identical to the primary selector FS6, they are also designed to absorb the first digit transmitted if this is the number 8, characteristic of office 8. This arrangement is necessary because an arrival selector at office 8 is activated automatically when the receiver is picked up in office 86, it therefore receives the first digit sent.



   The trunk circuits, represented by the trunk circuit T6 operated in one direction and the trunk circuit T5 operated in both directions, which carry traffic from office 8 to satellite 86 are accessible from the sixth level of the selectors. The arrival selector IS3 and IS4 and the primary selector IS6, but the sixth level of the arrival selector IS5 and IS6 is not used as arrangements have been made in satellite office 86 to allow subscribers to the latter to take local calls without using the interchange circuits between offices.



   The eighth level of selectors in office 8 are unused now, but the ninth level of these selectors provides access to outgoing trunk circuits to the operated office 9, such as trunk / one way Tl and trunk circuit operated in both directions T2, through repeaters such as R3 and R4. The ninth level of inbound selectors IS3 and IS4 is unused because these are inbound selectors carrying traffic from office 9.



   The tenth level of local primary selectors such as FS6 provides access, through outgoing repeaters such as OR2, to outgoing trunk circuits, such as OT2, to the public office, but the tenth level

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 inbound selectors is unused because each office has direct trunk circuits to the public office.



   Satellite Office 86.



   In satellite office 86 the subscriber lines have. access via preselectors to repeater selectors. For example, the line of station A4 (N 8625) has access via the individual preselector LSIO to the aelector-repeaters, one of which is the repeater selector SR. The switching mechanism of this repeater selector is the same as that ordinarily used as a rotary switch, it has access to the junction circuits as shown in the plan.

   Normally when the selector-repeater SR is switched on the switching mechanism rotates until it engages on a junction circuit such as T4 or T5 which goes to the neighboring office, thereby an arrival selector such as IS5 or IS6 is put into service in the office 8 as soon as the receiver of a station connected to the satellite office is picked up.



   The arrangement is such that if the call is to be routed through office 8 to a line in that office or to office 9 the switching mechanism of the SR repeater selector does not function further and the call continues at as the number is transmitted, the SR repeater selector working more or less retorts a pulse repeater.



   The MS marking switch is provided for controlling the selector-repeater switching mechanism in the event that communication needs to be established locally in the satellite office or directed to the public office.



  For example, if the first digit emitted is the digit 8, the marking switch MS returns to idle and prepares to cause a new operation of the switching mechanism of the selector-repeater SR if the digit 8 '

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 is followed by the number 6. In this case the five positions in the bank of the switching mechanism associated with the local connectors, such as the LOC4 connector, are marked and the switch rotates until it meets the first connector. free local tor to which it connects, this connector receives the last two digits of the number to establish communication.



   On the other hand, if the first digit emitted is the digit 0 the switching mechanism of the selector-repeater SR rotates until it meets the first free junction circuit to the public office, such as the outgoing junction circuit. OT3, it connects to this one which is associated with the outgoing repeater OR3.



   Calls which terminate at the satellite office are received through one of the trunk circuits operated in both directions such as T5 or through the trunk circuit operated in one direction T6, they are routed by an incoming connector such as IC2 or through the incoming connector ICI. Each of the incoming connectors has a transfer preselector, such as LS11 and LS12, associated with it for the purpose of performing local transfers within the adjoining office as described above. The outgoing repeater OR3 is likewise provided with a transfer pre-selector LS9 enabling a local transfer to be carried out during a communication with the public office.

   The local connector L004, however, is not equipped for the transfer service as it can never be used to establish communication with the central public office, whether inbound or outbound.



   After having described the junction diagrams shown in fig. 2, 3, 4 and 5 we will stop somewhat at the description of the general aspects of the circuits, represented in figs. 6 to 48, in which the devices shown in fig. 2,

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 3, 4 and 5 are shown in detail. As shown in assembly figure 52 in fig. 6 to 30 show the devices located in office 9; Figs. 31 to 41 show the devices / in the office 8 and fig. 42 to 49 show devices located in satellite office 86.



   The line circuits LCl to LC4 of fig. 2.are shown in fig. 6 to 9 and the finder F1 of position 1 which has access to these line circuits in common with the other researchers is shown in figs. 10 and 11.



   Fig. 12 represents the primary selector FS1 of FIG. 3 connected to the finder F1 which will be used as a call switch in the connection circuit, the finder F1 of fig. 10 and 11 being the response switch of this connection circuit,
Fig. 13 shows the DCS delayed call selector of fig. 3 which is one of the selectors accessible from the first level of researchers, it is intended for setting up delayed communications.



   Fig. 10 represents the arrival selector IS2 associated with the junction circuit operated in both directions T2 and with the repeater R1 of FIG. 21;
Fig. 15 shows the arrival selector LS1 which a selector is / identical to the arrival selector of fig. 14 and is associated with the junction circuit operated in a seal direction Tl coming from office 3;
Fig. 16 represents the prospectors L2 and L3 which are associated with stations A1 and A2 respectively and which have a common access (shared with the preselectors LS1 and LS4) to the primary selectors such as FS5 via secondary preselectors such as the one shown schematically in SES;

   
Fig. 17 shows the starting repeater OR1 of fig. 3 associated with the OT1 junction circuit going out to the

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 public office;
Fig. 18 represents the connector BC of the annex office of FIG. 3 which has access to lines to other annex offices such as that associated with the LC4 line circuit of FIGS. 2 to 9;
Fig. 19 shows the TC trunk connector which has access to trunk lines as shown in fig. 3 by means of wires such as 1551 of FIG. 2 and also to lines to other annex offices via wires such as 1451;
Fig. 20 is a rectangle which represents the repeater R2 associated with the junction circuit operated in a single direction T3 going towards the office 8.



   Fig. 21 shows the repeater RI associated with the junction circuit T2 operated in both directions and connecting the offices 9 and 8, and also associated with the arrival selector IS2 of fig. 14. The repeater RI is the same as the repeater R2 in fig. 20 except that the repeater R1 is provided with a transfer relay 1711 which transfers the wires of the junction circuit T2 of the selector of FIG. 14 to the outgoing wires of the repeater when the latter is seized; -
Fig. 22 represents the secondary selector SES of FIG. 3 which is accessible from the first level of the primary selectors and which has access to groups of connectors such as the local connector LOC1 of FIGS. 3 to 23;

   
The local connector LOC1 in fig. 23 of its 100 groups of bank contacts have group 1250, fig.16, associated with the LS2 preselector of station A1;
Fig. 24 shows the 2000 starter leads (which are connected to the individual starter leads of the - line circuits as shown in fig. 6 to 9, depending on the levels of the searcher bank through which these circuits are reached) which control the relay common boot 2001

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 and which guide searchers to appropriate levels when searching for the calling line.

   Fig. 24 also shows the distributor common to the four positions of the table and which distributes the incoming calls to the operators;
Figs. 25, 26 and 27 represent the position relays and the keys of position 1;
Figs. 28 and 29 show the transmission circuits SL1 and SL2 as well as the equipment associated with them, including the digit keys DK;
Fig. 30 shows the control circuit of the transmitter of the transceiver RS as well as a rectangle indicating the transceivers RS;
Fig. 31 shows the repeater R3 of the office 8 which is associated with the junction circuit T1 going out to the office 9, and which is identical to the repeater RI shown in detail in FIG. 21;

   
Figs. 32 and 33 represent the destination selectors IS3 and IS4 associated with the junction circuits T3 and T4 which route the traffic coming from the office 8. The selector IS3 being identical to the selector represented IS4 jammed indicates a rectangle;
Fig. 34 shows the repeater R4 associated with the junction circuit T2 operated in both directions and which is identical to that shown in FIG. 21;
Fig. 35 represents the line of station A3 (N 8225) connected to office 8 as well as the preselector LS7 which is associated with it and the preselectors LS6 and LS8, which all have access to the primary selector FS6 which is identical to the selector FS5 shown in detail in fig. 16 except that the brushes of the primary selector FS6 (in office 8) fall from the eighth level instead of falling from the ninth level.



   Fig. 36 shows the local connector LOC3 which is identical to the local connector LCC1 shown in detail in fig. 23.

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   Fig. 37 represents the outgoing repeater OR2 associated with the outgoing junction circuit T2 which ends at the public office. This repeater is identical to the OR1 repeater in FIG. 17;
Figs. 38 to 41 show the arrival selectors IS5 and IS6 associated with the T4 and T5 junction circuits for routing calls from the satellite office 86, as well as the repeaters R5 and R6 associated with the T5 junction circuit operated in both directions and to the trunk circuit T6 for routing calls to the satellite office 86;
Figs. 42 and 43 represent the incoming connector IC2 of the office 86 associated with the junction circuit T5 operated in both directions, it has access to the local lines of the satellite office to establish the communications entering this office.



   Figs. 44 and 45 show the incoming connector ICI (a replica of the incoming connector IC2) associated with the incoming ring circuit T6;
Figs. 46 and 47 represent the selector-repeater SR from office 86 accessible to preselectors such as LS10 from station A4 (N 8625) as well as to transfer preselectors LS9, LS11 and LS12;
Fig. 48 shows the local connector LOC4 of fig. 3 which is accessible to the selector-repeater such as SR of FIG. 39 and who has access to the local lines of the satellite office; finally, fig. 49 represents the outgoing repeater OR3 accessible to selector-repeaters such as SR and associated with the outgoing trunk circuit OT3 which terminates at the public office.
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   So that we can more easily follow the developments of the description which will follow certain characteristics.

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 Special ticks, but of a general nature, which form an integral part of the system set forth here and which have not been specially brought to light in the foregoing discussion will be listed below:
1. As is customary, the lines in the adjoining office are divided into '-, full service lines and restricted service lines. Full service lines can get and receive communications to and from the central office, restricted service lines do not have this privilege.

   The trunk circuits leading to the public office being accessible from the tenth level of the primary selector used by the subscribers of the annex office, the primary selectors are arranged in such a way that they route calls or not through the tenth level depending on whether it is whether or not there is a loose connection in the preselector of the calling line, this connection being made to the preselector of each restricted service line.



   Calls coming from the public office to the annex office are accepted or refused at the connectors having access to the line called in the annex office. Each conne ctor has a relay recording the class to which the subscriber belongs, it automatically draws into the circuit of the fourth incoming wire when the call comes from the public network, but not in the other cases. The connector also has a class test relay which detects the presence or absence of an earth on the fourth wire of the group seated at the called line so that communication from the public office is admitted or rejected. according to the alasse to which belongs the. called line.



   In addition, the selectors used by the operators are provided with discrimination means which prevent the establishment of communications coming from the public network via junction circuits between annexed offices.

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   2. It has already been mentioned that the operators cannot establish a connection to a junction circuit leading to the public office via one of the regular primary selectors (linked to the researchers) but the operators have call selectors. delay (DCS of Figs. 2 and 9) by means of which any of them can establish a delayed call between a line of the public office and a local line of the annex office or between two trunk circuits between offices-annexes.

   Links to prevent the establishment of a communication between the public office and a restricted service subscriber of the annex office via a delayed call selector and one of the operator connection circuits, the selector d The delayed call is arranged so that, when it is connected to an outgoing trunk circuit towards the public office, the attraction of the relay registering the class in the local connector takes place as in the case of a call coming regularly of the public office.



   3. In order to give an interesting characteristic to the service provided by the annex office, the connectors which are used to establish the communications passing through the attendant table are provided with an offer relay.



  When one of the subscribers of the annex office particularly wishes to be put in touch with another subscriber whose line is busy, he calls the attendant of the pass table, this operator establishes a link to the selector serving the busy line. and then operates the supply relay of the connector discussed above to temporarily plug into the busy line. The called subscriber can then hang up and then go off hook to accept the urgent call. It should be noted that a special tone is sent on the busy line when the call for offers arrives on this one so as to warn the subscribers in communication that the operator is intervening on the third party. the circuit.

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   4. It should be noted that one of the special characteristics of the circuit presented here is that the number of wires of the connection circuits is reduced to a minimum; there are only four wires connecting the selectors to the connectors: the positive and negative conversation wires, the third wire or control wire (abbreviated as C wire) and the fourth extra control wire (abbreviated EC). The third wire or wire 0 is also commonly referred to as the connection circuit release wire.



   The fourth wire is used to send a class indicator pulse from one switch of a section train to the next switch when this is seized, it is used to turn on the offer relay whose it was Question above when an urgent call should be offered when the line is busy; it is also used as a supervisory wire to give a. callback signal or an end signal in the case of a communication established through the passage table and an interurban line or a line going to a manual central office.



     5. One of the special characteristics is the arrangement provided to meet a number of special conditions required for the control to be carried out on two-wire trunk circuits between offices. In addition to the normal control of circrzi. ts allowing the establishment of communications, the blocking and release of these, as well as the supervision given by reversal of the direction of the current, the sending of a pulse en-registering the class on one of the wires of the control circuit. junction between offices, when the junction circuit is seized, causes the momentary attraction of a differential recording control relay to the remote office to establish the required class conditions;

   sending a communication offer pulse on one of the wires of a junction circuit between offices when

  <Desc / Clms Page number 23>

 a call is made on a busy line unbalances the circuit to allow this relay to pull into the remote office to transmit an offer pulse to the connector; when it comes to catching subscribers making malicious calls by blocking the communication they have requested, opening one of the line wires at the remote office causes the postponement of the blocking of the connection through the two connecting wires to the original office where the lock is held. The characteristics just listed are valid for trunk circuits working in tandem when communication is established between office 9 and satellite 86.



   The characteristics given above and many others will become more tangible on reading the following description:
Detailed description.



   The invention having been described in general, a detailed description of the operation of the system will be given below.



   Outgoing call: office 9.



   It will first be assumed that the subscriber of the full-service station A1, FIG. 3 and 16, wishes to make a call to the public office, for this purpose he picks up his receiver (not shown) and emits the number 0.



   When you pick up the receiver from station A1 the negative and 'positive wires are bridged as usual, which closes the circuit of relay 1231 of preselector LS2 through contacts controlled by armature 1235. When the relay 1231 attracts it places a positive on wire C at its internal spring, at the same time it disconnects the winding 1232 from the electromagnet of the preselector, with its upper spring it closes the circuit of the winding 1233 by the intermediary

  <Desc / Clms Page number 24>

 of the chain earth wire associated with it.

   At this point it can be observed that preselectors such as LS2 are divided into two groups each of these groups having access to a different group of trunk circuits and being directed by a separate main control switch.



   When the circuit of the winding 1233 is closed the armature 1234 is attracted which presses the springs of the preselector on the contacts of the connection circuit which have been preselected by the main control switch (not shown); for greater convenience, it can be assumed that this is the connection circuit associated with the secondary SLS preselector. Armature 1235 is also drawn in and disconnects the incoming line wires from relay 1231 and positive, resulting in delayed line relay 1231 dropping.



  Winding 1232 is energized through the positive applied to pre-selector wire C by the lower spring of line relay 1231 and through armature 1234.



   Only the brushes of the SLS secondary preselector have been shown. This preferably is of the rotary type, it is provided with the usual line relay and normal switching relays. Wire C of the secondary SLS preselector is connected to earth in the usual way via the line relay (not shown) to keep the 1232 winding of the LS2 preselector under current, which acts as a blocking winding. after releasing the line relay 1231 and when the circuit of winding 1233 is closed.



   It can be assumed that the primary selector FS5 is the one entered by the / secondary selector SLS. Under these conditions the line relay 1201 draws negative and positive incoming wires and the calling line into the loop, the upper winding of this relay being connected to the negative pole of the battery supplying the office.

  <Desc / Clms Page number 25>

 lower bearing ce connected to earth through contacts 1213, relay contacts 1205 of wire 1215 and the source providing the invitation tone to tra, ns- put (represented by a dotted line terminating in positive) . Pulling relay 1201 closes the circuit of relay 1202,

   this circuit passes through relay contacts
1206. Relay 12C2 draws and places at its upper contact a positive on incoming wire C, which provides a blocking circuit to winding 1232 of preselector LS2 after releasing the line relay of secondary preselection SLS.



   Relay 12C2 also forms the relay circuit
1203 which opens in one. point the circuit of the releasing electromagnet 1209 and prepares the circuit of the ascending electromagnet 1207 at its lower inner contact, while at its lower middle and lower contacts it prepares the-, air- cooked. which will have the role of absorbing a number in the selector, these circuits contain the relay 1205. The relay
1203 also closes the circuit of the polarizing winding of relay 1206 (this is the lower winding) plus it prepares a test circuit for the upper winding of relay 1206 through brush C of the group of broom
1200.



   When the calling subscriber hears the invitation tone to be transmitted sent on the line by the call wire 1215 he sends by means of the dial / (not shown) the number "0" which is assigned to calls to the telephone. public office, the 1201 line relay releases momentarily ten times. Each time it releases it forms through contacts of the attracted relay 1203 the circuit of the ascent electromagnet 1207. The electromagnet 1207 therefore operates ten times and raises the brushes 1200 step by step until that they come to be placed in front of the tenth level of the bench contacts. The tenth level contacts of the selector used here, as shown in fig. 3,

  <Desc / Clms Page number 26>

 lead to outgoing junction circuits such as the OT1 junction circuit of FIGS. 3 and 17.



   Relay 1204 attracts under the action of its lower winding- Bent when the first pulse is sent to the ascent electromagnet 1207. As this relay is provided with a core surrounded by a conductive sleeve, as As shown by the double lines representing the core, this relay (as well as the release relay 1202 and others with the same representation) is delayed on release and remains attracted while sending the pulses.



   When the sending ceases the relay 1204 releases and at its lower contact closes the circuit of the rotation electromagnet 1208, this circuit comprises contacts of the relay 1201, the own control contacts of the rotation electromagnet 1208 , the engagement contacts 1210, the relay contacts 1204, the ninth level spring 1217 and its left contact, the contacts of the release solenoid 1209.



   The self-controlled rotation electromagnet 1203 works like a buzzer and drives the brushes 1200 in the contact field, from the tenth level 1: the search for a free ionction circuit.



   It can be assumed that the outgoing junction circuit OT1, fig. 17, is the prenier which has been found free and that it is therefore seized by the brushes 1200 at the terminals such as 1300. When the terminals .1300 are reached, the brush C of the selector meets a negative on the terminal C group 1300 through the occupancy key contacts 1307, relay contacts 1302 and resistor 1309.



  The top winding (test winding) of relay 1206 is energized in a circuit from brush C to the incoming C grounded wire of the selector, (it is grounded to the top contacts of the 1202 release relay) .

  <Desc / Clms Page number 27>

 



   The selector brushes having been raised to the tenth level or level "O", the spring of level "0" 1216 has been actuated and placed in its alternate position which transfers the left terminal of the test winding of the relay
Through 1206 from the incoming wire C to the EC wire entering the selector FS5. this precaution the relay 1206 test circuit is only active in the case where the calling preselector has a free connection (such as connection 1236 of the preselector LS2) allowing the EC wire of the selector to obtain a positive from the thread C of it.

   Connection 1236 therefore earths the EC wire entering the FS5 selector, the positive is extended through the right contact and the spring 1216 of level "0", and through the upper contact of relay 1203, up to than at the left terminal of the 1206 relay test winding.



   When the test winding of relay 1206 is energized in series with resistor 1309, this relay pulls and closes the circuit of its middle winding or blockaze winding of the relay through the grounded C wire; it connects the incoming wire C to the brush C, without passing through the test winding of the relay, it disconnects the positive of the spring of the line relay 1201 to stop the rotational movement and to prevent a premature release of the selector; finally it disconnects the incoming positive and negative wires from the winding of the line relay 1201 and extends them through the negative and positive brushes of the group 1200 to the corresponding wires entering the starting repeater OR1.



   In repeater OR1 the relay 1301 draws in the circuit of the calling line and through the differential relay 1305 of transfer control it closes the circuit of the release relay 1302, this relay applies a positive to the incoming wire C which provides a blocking circuit to relay 1206 of selector FS5 and preselectors LS2 and SLS before the

  <Desc / Clms Page number 28>

 delayed relay 1202 of the selector has had time to release.



  Relays 1202 and 1203 slowly release.



   Line relay 1301 orally closes a bridge on the outgoing wires of the CT1 junction circuit through the left windings of the 1330 translator coil and / or the associated resistor, thereby preparing the commissioning of the switching devices. switching of the public office.



   It should be remembered that the invitation to transmit tone was sent via the common wires 1215 associated with the selector FS5 to warn the subscriber of station A1 that he could begin to send the pulses.



  This tone is no longer received when the FS5 selector has tripped to enter the outgoing repeater OR1. Since the subscriber calls the public office he now receives another invitation to transmit which arrives from the public office through the GTI junction circuit or he receives no indication, depending on the nature of the switching devices to which terminates the CT1 junction circuit.



   In any case, the plague subscriber A1 then sends the digits of the number he wishes to call in the public office, this causes the repetition of the pulses at the lower contacts of the line relay 1301 of the repeater OR1 and starts the office devices. public who establish the requested communication. The conversation can then begin.



   Information call during a call
 EMI28.1
 ÔOETµETG7 With the aim of explaining how an information call can be made when a communication is initiated between the annex office and the public office, it will be assumed that the subscriber of the station Al wishes to obtain additional infermation from a other subscribers of the annex office before cutting off the communication in progress with a subscriber of the public office. In this case, after having asked the subscriber of the public office to

  <Desc / Clms Page number 29>

 wanting to wait a moment, subscriber A1 of the annex office momentarily pushes the button mounted on his set, which places an earth on the positive wire of his line.

   The momentary action of the earthing button L of the calling station momentarily unbalances the current flowing through the differential relay 1305, which momentarily attracts. It closes the circuit of the upper attraction winding at the first stroke of relay 1304. through contacts of this relay which attracts enough to close its preliminary contacts only (these are its lower inner contacts adjusted slightly).



   A blocking circuit closes for both relay windings in series through relays 1303 and 1304, but this blocking circuit is inactive as long as the initial circuit of the top coil of relay 1304 remains closed.



   When the calling station push button is released and relay 1305 releases the two windings of relay 1304 are supplied in series and the relay pulls fully.



  The negative and positive wires of the repeater OT1 are disconnected from the left windings of the translatrioe coil 1330 and transferred to the corresponding wires of the preselector LS1, a blocking circuit of the relay 1302 being prepared through the wire C of the preselector LS1.



   The line relay then releases, but without effect, because the outgoing wires are bridged by the lower contacts of the transfer relay 1304 and the release relay 1302 is kept attracted through the wire C of the preselector LS1, this one operates in the circuit of the calling line to enter another primary selector identical to the primary selector FS5 and allow the subscriber of the set A1 to establish with any one of the other subscribers of the annexed office. It will be noted that the LS4 preselector is not represented completely because it is identical to the LS2 preselector.

  <Desc / Clms Page number 30>

 
 EMI30.1
 Release of the communication established for the information aphel.



   When the subscriber of the set Al has finished his information conversation and wishes to cut off this communication in order to get back in touch with the subscriber of the public office, he momentarily pushes the button on his set which momentarily switches to the line to earth to attract relay 1305. At this moment when relay 1305 attracts it closes the circuit of relay 1303 through contacts of relay 1304.



  Relay 1303 closes a new blocking circuit for relay 1304 while opening the initial blocking circuit for that relay. As a result, when the relay 1305 releases and opens the attraction circuit of the relay 1303 it also opens the circuit of the relay 1304. The relay 1303 is delayed, so it keeps the blocking circuit of the relay 13C4 open for a sufficiently long time. to allow the latter to release and transfer the connection from the preselector to the outgoing trunk circuit OT1. The LS1 preselector as well as the other organs of the transfer circuit returns to idle.

   The relay 1301 attracts again and maintains the release relay 1302 locally blocked, L its lower contacts it also maintains the bridge placed on the outgoing junction circuit. Relay 1203 consists of a pair of lower contacts which maintain the bridge will make ± during the transient period while the connection is transferred from the preselector LS1.



   Release of the connection established to the public office.



   When the subscriber of the set A1 has finished his conversation with the subscriber of the public office, he hangs up his receiver (not shown) which releases the relay 1301 and opens the outgoing trunk circuit OT1. to allow the release of the automatic equipment of the public office at the same time.

  <Desc / Clms Page number 31>

 



   Relay 1301 orally cuts the delay relay circuit
1302 which is associated with it allowing it to release after a short time and thereby remove the positive connected to the wire C which is associated with it. Relay
1206 of the primary selector FS5 releases in its turn, and the coil 1232 of the preselector LS2 is switched off, which causes the reinforcement to return to the normal position.
1235 and 1234. The armature 1234 opens the connection between the preselector LS2 and the secondary preselector, SLS.



   In the primary selector FS5 the electric circuit. Release tri-magnet 1208 closes at the lower contacts of relay 1206 via contacts of relays 1201 and 1203, and engagement contacts 1211. The release electromagnet attracts and causes the return to the reset position. - pos of the primary selector FS5 in the usual way, therefore the circuit of the release electromagnet is open at the engagement contacts 1211.



   If we examine what happens in the starting repeater OR1 we see that the relay 1306 of this one is connected to wire C. This relay can be used when it is desired to control the application of a positive to a Common wire that indicates whether all outgoing trunk circuits are busy or not. This wire marked 1308 and known as the common occupancy wire is shown on the plan, associated with relay 1306.



   It is common to all the departure repeaters in the same office.



   When all of these repeaters are busy, all relays 1306 are energized and the positive is removed at all points of wire 1308. This wire can terminate in a counter or can be used for some other purpose.



   It can be pointed out here that there is no connection such as 1236 in the LS3 preselector because it serves a restricted service line. Therefore if the subscriber of the station
A2 picks up his receiver and emits the number "0" in

  <Desc / Clms Page number 32>

 intending to take a call to the public office, the primary selector switched on (for example the primary selector FS5) will not be sure to enter a junction circuit on the tenth level because there is no no positive on the incoming EC wire from the selector. It was previously noted that a positive must be placed on this wire for the test coil of relay 1206 to be energized.

   In the current case, the selector continues to turn until contacts 1212 and 1213 close, the busy tone is then sent to the calling line.



   Local communication in ¯lēbureaū9.



   In order to explain the operations which take place in office 9 for establishing a local call, it will be assumed that the subscriber of the set A2 (N 9225) wishes to converse with the subscriber of the set. A1 (N 91225). If this is the case, the subscriber of set A2 picks up and sends the digits of the desired number, i.e. 91225.



   When the receiver is picked up the LS3 preselector operates in the way that was explained in the case of the LS2 preselector to enter a free secondary preselector (such as SES) and the secondary preselector in turn enters a free primary selector, the primary selector FS5 , for example. The relays 1201, 1202 and 1203 of the primary selector FS5 attract one after the other to put the selector into service and the subscriber of the calling station A2 receives the invitation to transmit tone which is brought from the common wire 1215 through the 'intermediate the lower winding of relay 1201.



     When the calling subscriber issues the attic digit, 9, of the desired number the relay 1201 momentarily releases nine times thereby the ascending electromagnet 1207 raises the brushes 1200 to face the ninth level of the bank contacts. At this moment the shaft spring 1217 of level "9" is actuated,

  <Desc / Clms Page number 33>

 it goes into the working position and at one point opens the normal circuit of the rotation electromagnet 1208, at the same time it prepares the circuit of the release electromagnet 1209.



  This causes the absorption of the first digit.



   Under these conditions when the series relay 1204 (which is drawn during the ascent movement) returns to rest at the end of this movement it applies an earth to the spring 1217 of the level "9" as it has been described previously. At this moment, however, the spring 1217 is in the working position and the earth is extended by the intermediary of the contacts of the relay 1205 ', the contacts of the relay 1203 attracted and the engagement contacts 1211 up to 1'. release solenoid 1209.



  The release electromagnet 1209 actuates its springs while causing the selector Fs5 to be returned to the rest position.



  At its outer contacts the electromagnet 1209 keeps the circuit of the rotation electromagnet 1208 open after the spring 1217 of the level "ç" has returned to rest and until the engagement contacts 1210 are closed. are open. At its internal contacts the releasing solenoid 1209 establishes a blocking circuit for itself without the aid of the spring 1217 until the engagement springs 1211 are opened.



   When the rest position is reached and the engagement contacts 1210 and 1211 have opened in the usual way, the release solenoid 1209 remains momentarily drawn into the blocking circuit which includes the lower winding of the relay 1205, the lower contacts of this relay, the contacts of the auxiliary relay 1203 and the internal contacts of the release solenoid 1209 and leads to the positive through the contacts of the drawn line relay 1201 and the contacts of the relay 1206. Relay 1205 draws into this circuit and closes its blocking circuit at its inner top contacts and through its top winding.

   Relay 1205 also opens its

  <Desc / Clms Page number 34>

 attraction circuit and the circuit for blocking the release electromagnet 1209 at its lower contacts, thereby the release electromagnet releases. Relay 1205 at its lower spring connects the rest contact of spring 1217 to the working contact of this group to allow rotation on the ninth level while at its lower inner spring it opens the release circuit?;. through which the electromagnet of release 1209 had attracted to drop the brushes.

   At its lower contact, relay 1205 substitutes a direct earth for the common wire 1215 of the invitation to transmit tone which stops the sending of this tone on the calling line after the transmission of the first digit which complies with the normal practice.



   When the calling subscriber emits the second digit (1) of the requested number, the ascending electromagnet functions again and brings the brushes in front of the first level of the bench contacts.



   When the relay-series 1204 releases the self-controlled electromagnet 1205 drives the brushes 12CO in the field of the first level contacts in search of a free secondary selector. Assuming that the SES secondary selector, fig. 22, which is available to the primary selector FS5 at terminals such as 1800, is the first that is found free, the switching relay 1206 draws in the circuit of the brushes C which is associated with it and of the wire C which goes to the terminals 1800 to the SES secondary selector. A negative polarity indicating that the device is free is normally applied to the input wire 0 of the secondary selector SES through the top winding of the 1304 series relay, the engagement contacts 1812 and the key contacts. occupation 1816.



  When FS5 selector brush C encounters this polarity, switching relay 1206 pulls in to extend the calling line to the SES secondary selector.

  <Desc / Clms Page number 35>

 



   In the secondary selector SES the relay 1804 draws in the circuit of the incoming wire C and opens at one point the circuit of the rotation electromagnet 1808. The relay 1801 draws in the loop of the calling line and closes the circuit of the relay. 1802 which attracts and causes relay 1803 to attract in addition to applying a blocking positive to the incoming C wire through the upper contacts of relay 1802.



   When the calling subscriber transmits the third digit (2) of the desired number, line relay 1801 momentarily releases twice. Each time it releases it closes through contacts of relay 1802 the circuit of the ascent electromagnet 1807. The ascension electromagnet brings the brushes 1850 in front of the second level of the bank contacts (the level in which are the 1851 terminals). The relay 1804 remains attracted by the action of the pulses which pass through its lower winding in parallel with the circuit of the ascending electromagnet 1807, after the initial circuit of the upper winding of this relay has opened. to the engagement contacts 1812, at the first step of ascent of the switch.



   The engagement contacts 1811 prepare the circuit of the rotation electromagnet 1808, this one works like a buzzer through the contacts of the relay 1804, when this relay attracts at the end of the train of the pulses.



  If we assume that the 1851 terminals are the first which have been found free by the 1850 brushes rotating in the field of the second level contacts, these terminals (associated with the local LOO connector of fig. 3 to 23) are the ones on which the brushes remain engaged. The C wire associated with the 1851 terminals and entering the local connector LOCl, is normally marked with a negative polarity indicating that it is free, it is brought to it via the / con-

  <Desc / Clms Page number 36>

 upper tacts of the occupancy key 1926, engagement contacts 1923 and the upper coil of the relay 1906.



  As a result, the electrically polarized relay 1806 receives a current which flows from the brush C to the grounded wire C.



  By attracting, the relay 1806 stops the search movement and establishes the connection through the local connector LOC1 of fig. 23. SES selector relays 1801-1803 release, but relay 1806 remains engaged, by the action of its blocking winding (middle winding) connected to the grounded C wire, to maintain the connection established and for leave the circuit of the release solenoid open.



   In the local connector LCC1 the relay 1906 draws in the circuit of the grounded wire C and through the engagement contacts 1923, it opens at one point the circuit of the rotation electromagnet 1920 and prepares the Circuit of its lower winding and winding of the ascension electromagnet 1909.

   When SES secondary selector relay 1806 pulls to extend the calling line, local LOCI connector relay 1902 pulls into the calling line loop to close the 1904- relay pull circuit. Relay 1904 applies a podtive to incoming wire C to provide blocking circuit to the preceding switches; it opens the circuit of the 1921 release electromagnet at one point; it closes through contacts of relay 1911 the circuit of the lower winding of relay 1905.



  Relay 1905 has an additional winding which is presently incorporated in a closed circuit through contacts of release relay 1904 - which delays this relay on release. The reason for this arrangement will appear later.



   The relays 1904, 1905 and 1906 having attracted, the connector is ready to receive the tens digit (2) of the desired number. The 1902 relay releases twice momentarily

  <Desc / Clms Page number 37>

 when the number 2 is transmitted. Each time it releases, the 1902 relay magnet closes the 1919 electro / ascension circuit through contacts of the drawn relays 1905 and 1906. The 1919 electromagnet brings the 1900 brushes in front of the second level of bank contacts. The lower winding of the lattice 1906 is kept in circuit with the hoist coil / magnet 1919 after the initial circuit of the upper winding has been cut at the engagement contacts 1923.



   At the end of the ascent movement, relay 1906 releases and transfers the active circuit from the ascent electromagnet 1919 to the rotation electromagnet 1920.



   When the units digit (5) is emitted, five pulses are sent to the rotation electromagnet 1920 as a result the brushes 1900 are brought to the fifth group of bank contacts of the second level, these are those of the line of station A1, fig. 16. Relay 1914 draws into the 1920 rotational solenoid circuit and remains attracted during rotational motion. This relay shunts the lower contacts of relay 1913 to prevent premature opening of the rotation electromagnet circuit in the event that relay 1913 operates during the rotational movement when the brush C of the connector passes over the contacts of busy lines.

   At its upper spring, relay 1914 closes the attraction circuit of auxiliary relay 1915. Relay 1915 disconnects brush C from the coil of relay 1917 and transfers it to the upper coil of relay 1913 to enable the occupancy test. normal by brush C. It can be signaled that the 1908 class test relay is not active at this time because the class registration relay has not been switched on to connect the test relay of class 1908 to the EC brush of the connector.



   The called line is busy.



   If we assume that the line of set A1 is busy

  <Desc / Clms Page number 38>

   At the moment of the call, the relay 1913 attracts in the circuit of the brush C. Under these conditions, when the relays 1914 and 1915 release at the end of the sending of the pulse train, the blocking circuit of the relay 1913, which borrows upper winding, closes at contacts of 1915 relay and 1908 class test relay; Blocking circuit includes contacts from relay 1913, contacts from relay 1912, and top contacts from relay 1905.

   The relay 1913 being attracted, the relay 1917 is switched off; electro circuit '. rotation magnet is open at its lower contacts; relay 1912 is connected from. incoming EC thread for a reason which will be explained in more detail later; the busy tone is sent on the lower talk wire, it is brought by the common wire 1943 of the busy tone through the upper contacts of the 1913 relay and through the upper contacts of the relay 1912, this tone is sent to the calling line to notify the subscriber that the called line is busy. When he hears this signal the calling subscriber hangs up and thus allows the switching devices to free themselves.
 EMI38.1
 p2¯lip¯ē called-is free.



   If we now assume that the line from station A1 is free at the time of the call, relay 1913 is released when brushes 1900 reach the terminals of the called line and relays 1914 and 1915 release. In this case releasing relay 1915 results in connecting the lower terminal of relay 1917 to wire C of the connector, the upper terminal of the relay being connected through contacts of relay 1913 to ground taken at the upper contacts of the relay. 1905. As a result, relay 1917 attracts in the circuit comprising the brush C of the connector, the terminal C of the line of the station A1, fig. 16, the contacts of relay 1231 and the winding of relay 1232 of the preselector LS2.

   When-winding

  <Desc / Clms Page number 39>

 1232 alone is under tension the magnetic attraction is sufficient to make the armature 1235 work, but the armature 1234 is not attracted. The frame 1235 activates the springs which are associated with it and releases the called line of its normal connections.



   In the LCC1 connector, fig. 23, relay 1917 attracts after a short time (due to the action of the copper ring lining its core) to give time to the armature 1235 of the preselector to clear the line. Relay 1918 then attracts and disconnects the electromagnet from
EC rotation 1920 and relay 1914; it disconnects the brush / from the circuit which leads to relay 1908 when relay 1907 is pulled and connects it to the upper winding of relay 1916; closes its blocking circuit via the upper contacts of relay 1905; it applies a positive taken to the upper contacts of relay 1905 to brush C, which bypasses relay 1917 and allows it to release; finally it connects the negative brushes and pcs itif to the calling circuit through contacts of relay 1911.

   The inrush current coming from the return wire of generator 1941 borrows the contacts of relay 1911 and the contacts of relay 1918 to end up at the positive wire of the line of the station Al, the return to the negative pole of the battery. performing through the negative wire of the line and the top winding of the 1911 relay.



   When the called subscriber answers, the normal closing of the direct current bridge on the line wires causes the attraction of the relay 1911. By attracting, the relay 1911 closes its blocking circuit comprising its two windings connected in series. , he goes through the 1925 engagement contacts.



  Relay 1911 also opens the call circuit and closes the talk circuit, it also opens the circuit of relay 1905 but the latter remains momentarily attracted by the braking effect of its upper winding

  <Desc / Clms Page number 40>

 which is for the moment incorporated in a closed circuit through the contacts of relay 1904.



   Relay 1903 draws in the circuit of the line called in series with relay 1925. At its lower spring the relay 1903 closes the circuit of relay 1901 which draws to reverse the connection between the windings of the line relay
1902 and the incoming conversation wires which reverses the direction of the current in the calling line wires and allows supervision. This reversal is of no use in the present case (local call).



   The 1903 relay, by attracting, finally closes the circuit of the lower winding known as the 1908 class test relay, this relay now acts as a blocking relay. At its inner lower spring the 1908 relay prepares the blocking circuit of the 1910 relay, while its lower spring it bypasses the corresponding contacts of the 1911 relay thus re-establishing the attraction circuit of the 1905 relay before the latter has had time to switch off. release.



   Circuits remain in this state for the duration of the conversation.



   Quick release of the called line.



   In order to explain a special characteristic of release, of the called line which the connector of fig. 23 it will be assumed that the called subscriber is the first to hang up at the end of the conversation. When the receiver is hung up at the station called the 1903 relay releases and opens its lower spring the circuit of the 1901 relay, thus the 1901 relay releases and returns the connections to the normal position between the incoming conversation wires and the 1902 relay.



   The 1903 relay also opens the circuit of the 1908 relay to its internal spring. The 1903 relay releases a moment later and opens the circuit of the 1905 relay with its lower spring.

  <Desc / Clms Page number 41>

 



  The 1905 relay releases soon after and removes the earth from the brush C, at its upper spring, while at its inner upper spring it opens the blocking circuit of the 1918 relay which releases and disconnects the negative, positive and EC brushes. . The line of station A1 is thereby released and the preselector LS2 is again placed under the control of this line, it follows that the subscriber of station A1 can receive or send a call while the connector LCC1 of FIG. 23 is still kept in service by the calling line.



   When the calling subscriber hangs up his receiver, relay 1902 releases and opens the circuit of relay 1904, this in turn releases after a certain time and removes the earth of the incoming wire C to allow the release of the switches which previous. The relay 1904 also closes the circuit of the release solenoid 1921, thereby the connector is returned to the rest position in the usual manner. The release solenoid circuit is open at engage contacts 1922 when the normal position is reached, likewise the circuit of relays 1911 is open at engage contacts 1925. A polarity, indicating that the switch is become free, is given to the incoming wire C through the upper winding of the relay 1906, to the engagement contacts 1923.



   At this point we can explain how the release is carried out when the calling subscriber is the first to hang up his receiver. In this case the release of the line relay 1902 is followed by that of the relay 1903, at the same time the local circuit of the lower winding of the relay 1905 is opened to suppress the characteristic of the delay in the release of this relay, as a result, relay 1905 immediately releases following the opening of its circuit under the action of relay 1904.



   The called line is made free by deleting

  <Desc / Clms Page number 42>

 of. positive of brush 0 to the upper contacts of relay 1905 and by releasing the switching relay 1913 when its circuit is open to the upper spring inside the relay 1905. The connector is returned to the normal position, as previously described, when 1 ' 1921 release solenoid works after release-du. relay 1905.

   The other switches which had been put into service under the control of the line of station A2 to establish
 EMI42.1
 the communication which has been described previously, that is to say the preselectors LS3 and SLS as well as the primary selector FS5 of FIG. 16, return to the rest position as we have already explained. The SES secondary selector, fig. 22, is returned to the normal position by the releasing electromagnet 1809 when the relay 1806 releases due to the opening of its blocking circuit when the positive is removed from wire C to connector LOC1, fig. 23.



     Incoming call from the public network.



   As previously indicated, calls which terminate at the annex office and which come from the public office are received by an operator, they are then routed to the requested line of the annex office. For the sake of convenience, it will be assumed that a call is received from the public office on the incoming trunk circuit IT, fig. 2 to 7, and we explain how this call is directed to the line of station A1, fig. 16;

   the station A1 being a full service station that is to say which can receive calls coming from the public network - When the incoming trunk circuit IT is seized at the public office, the inrush current is sent on this circuit to attract the relay 401 of fig. 7, the lower winding of which is bridged to the incoming conversation wires, in series with the stopper capacitor normally found in this type of circuit. In

  <Desc / Clms Page number 43>

 attracting relay 401 closes its own blocking circuit at its internal contacts in series with the upper coil of relay 402 while at its upper contacts it disconnects its lower coil from. bridge of incoming conversation wires.

   When relay 402 attracts it connects wire 0, coming from terminal group 400, to its lower winding and to the winding of relay 403, thereby marking the LC2 line circuit as calling in the seeker's bench. FI of fig. 10 and in the benches of other associated researchers' -, the fourth position of the passing table. The relay 402 also closes the circuit of the lamp GC2 from position 1 via contacts of the relay 403, it places a positive taken through the contacts of the relay 403 on the starter wire 411 which is associated with it. It can now be pointed out that the group call lamp GC2 is common to a complete group of incoming trunk circuits, one of them being circuit IC.

   The group call lamp GC1 is likewise common to all circuits such as LC1 in fig. 6 and group calling lamps GC3 and GC4 are other lamps, each of which is common to a group of trunk circuits and represents a different type of calling lines.



   As indicated by the symbols associated with the group call lamps / referred to above, the respective wires which terminate in these also lead to lamps located in each of the other three positions. These group call lights are used to identify groups in which there are pending calls.
 EMI43.1
 chexcheur demaxrae soul.



   As indicated above the starter wire 411, associated with the line circuit LC2, has been grounded searcher 'by the relay 402 to cause the positioning of a /

  <Desc / Clms Page number 44>

 on the LC2 line circuit terminals in order to answer the call. The searcher starting system will be explained below. With reference . Fig. 24 which shows the common starter wire and the finder distributor, it can be seen that there are nine starter wires generally marked with the reference number 2000 and to which the numbers 2 to 10. These last numbers indicate the searcher levels (2 - 10) to which the 2000 boot threads are associated respectively.



   The wires 2 to 9 of the group 2000, as we can see, lead to the contacts of the vertical broom bank 712 of the FI researcher on which this brush engages when the main brushes 700 of the researcher are in front of levels 2 to 9 respectively. These wires are used to stop the seeker in front of the first calling level reached by the switch brushes as he rises to answer a call. They are multiple to all researchers as indicated by the common connection symbol placed near the vertical broom bank contacts 712.



   It will be observed that the tenth bank contact of the brush 712 is permanently grounded to stop the seeker when it reaches the tenth level. This arrangement is necessary because the tenth level among the threads 2000 of FIG. 24 is not connected to the vertical researchers' benches.



   Referring to fig. 2 it can be seen that the first level of searchers results in delayed call selectors such as TICS of FIGS. 3 to 13. The calls sent through the delayed call selectors are controlled by the attendant; for this reason there is no thread in the 20CO group associated with the first level of the researchers' bench.



   All accessible line circuits of a given level by researchers earth the corresponding wire

  <Desc / Clms Page number 45>

 of the starting wire group 2000 of fig. ' 24 through the various starter wires shown in FIGS. 6 to 9 (311,411, 511, 611). The common relay 2001 of fig.24 by attracting under the action of a positive placed on one of the starter wires 2000 causes the pilot light to light up at each of the positions, such as the pilot light 2004 in position 1;

   Relay 2001 also closes, through the contacts of relay 2005, the circuit of the starter wire from the position which has been preselected among the four positions by the distributor or to the next wire which must be selected by the distributor if none of them was not preselected.



   The preselection of a position by the distributor of FIG. 24 is carried out as follows: when the attendant is not busy making a call, she has been instructed to activate the conversation key of a free connection circuit in order to be able to answer a call without delay. entering. By means of indicator lamps associated with each of its connection circuits, an operator is able to know at any time which circuits are free and which are in service.



   The supervision, occupancy and blocking lamps 741, 742 and 743 in fig. 11, inform the operator of position 1 of the state in which the connection circuit is located, which is made up of the finder FI of the fig. 10 and the primary selector FSI of fig. 12.



     Preselection of a connection circuit comprising
 EMI45.1
 ùti6fiéE6fiéàEéjùi1b6îéG ± éùE7
If we assume that the operator in position 1. is not occupied and that it wishes to pre-select a seeker to answer a possible call and if it is further assumed that the busy lamp 742 is not on, which indicates that the FI seeker and the FSI selector associated with it are not in service, the attendant activates

  <Desc / Clms Page number 46>

 its conversation key K2 which can be, in practice, the right half of a key with three positions, the left half of which acts as a service key K1.



   When the key K2 is actuated the circuit of the lower coil of the connection relay 703 is closed through the common test lead 733. The test lead 733 is one of the common leads contained in the cable 3 (which is one of the three multiplication cables that connect the equipment in position 1 to the group of connection circuits assigned to it). Referring to fig. 25 it can be seen that test lead 733 is normally grounded to the contacts of relay 2104.



   While attracting, the relay 703 of the FI finder is blocked with the wire 734 which is also part of the cable 3. The relay 703, its various contacts. Completes the connection between the connection circuit and the equipment of the position. This connection had been made partially when the conversation key K2 had been activated.



   In the positional equipment of fig. 25, the relay 2104 attracts through the blocking wire 734 into the blocking circuit of the connection relay 703. By pulling, the relay 2104 disconnects the ground from the test lead 733 thus preventing inadvertently operate another connection relay such as 703. Relay 2104 also disconnects the associated talk leads from the windings of the RC translator coil (used for monitoring) and extends these up to the operator's equipment.

   Via the contacts of the pilot relays 2110 and 2111, relay 2104 also extends the positive up to the winding of relay 2112 which prepares the circuit of signaling relays 2105 to 2107 for its upper contacts. earth the starting and marking wires of distributors 2031 and 2032, finally it connects the starting wire 2033 to the starting wire 727 which goes, through

  <Desc / Clms Page number 47>

 cable 1, to the junction circuit which has been preselected.



   If it is assumed that the distributor is in the normal position shown, the application of a positive to the starting wire 2031 has the result of causing the successive attraction of the relays 2021,2022, 2023 and 2024 which operate the test. the position in which a connection circuit has been preselected in the manner indicated above.



  The pre-selected position (position 1) is characterized by the earth which is placed on the marking wire 2032 which is associated with it.



   When the distributor's relay 2021 attracts, when its circuit is closed, it connects its lower spring, the common starting wire to the starting wire 2033; it connects relay 2025 to the marking wire 2032 from position 1 to its middle spring and 1, its internal spring it closes the circuit of relay 2022 (associated with position 2 through contacts of relay 2025 ). In practice, the 2021 to 2024 relays although they are of the fast-acting type have a relatively hard setting, while that of the 2025 relay is relatively light. As a result, relay 2025 attracts under the action of the marking wire 2032 grounded through the contacts of relay 2021, to open the circuit of relay 2022 before the latter has had time to attract.



  Relay 2025 and Distributor Relay 2021 will remain pulled through wires 2032 and 2031 until the next call has arrived and until it is answered.



  At this point it can be pointed out that in the case where a similar preselection is carried out one of the other positions when the distributor of FIG. 24 is in the normal position the operation is identical to that which has just been described except that the relays which follow relay 2021 attract success-

  <Desc / Clms Page number 48>

 thereafter until the position in which there is a preselected relay has been located, at this point the relay 2025 is drawn, as said above, leaving that preselected position.



   Searching for the circuit of the calling line.



   Grounding of the starter wire 411, as stated above, and the resulting pulling of the common starter relay, through the level starter wire, corresponding to 2000, causes the application of a starting positive through the contacts of relay 2021 of the distributor on the starting wire 2033 coming from the operator position. The positive connected to wire 2033 is extended '- through the contacts of relay 2112 and through the wire start 727 of cable 1. From this starter wire 727 the positive is extended, through the lower contacts of relay 703 of the FI finder, through the engagement contacts 715, to the lower winding of relay 712 of the FI researcher.



   The relay 702 attracts under the action of its lower winding and at its lower contacts connects its lower winding to the starter wire 727. through contacts 714, without the aid of engagement contacts 715, in order to produce an automatic return to the rest position and a new start in the event that the seeker passes over the calling line without finding it.



  At its upper internal contacts the starter relay 702 prepares the circuit of its upper winding, it grounds the wire 717 at its upper spring to close the ignition circuit of the occupancy lamp 742; while at its lower spring it opens the circuit of the release solenoid 711 at one point and applies it positive to the wire 718, thereby closing a circuit through the connectors.

  <Desc / Clms Page number 49>

 Tacts of relay 708 to turn on blocking lamp 743 and close the circuit of the bias winding of relay 701.

   It also results from the application of a positive to the wire 718 that the attraction circuit of the ascent electromagnet 709 closes through the contacts of the relay 701, 720 and 719 to start the ascension movement of the seeker. searching for the level in which the calling line is located.



   When the ascent magnet 709 operates, it closes the circuit of relay 720; this attracts and transfers the winding of the ascent electromagnet 709 from the wire 718 to the vertical brush 712 via the lower winding of the relay 719, thereby opening the circuit. The ascension electromagnet 709 fires. The ascending electromagnet releases and opens the circuit of relay 720, causing the relay to be released. The ascension electromagnet is working again.



   The cycle of operations which have just been described is repeated until the brush 712 'comes to engage on the vertical contact which was previously grounded, when the brushes 700 come to be placed in front of the level of the bank contacts in which the calling line is located.



   When the finder brushes reach the level where the calling line is located, the vertical brush 712 encounters a positive on the test lead which is associated with that level. Hence when the relay 720 draws again when the electro - ascent magnet 709 brought the brushes up to the calling level it closes a blocking circuit for the ascent electromagnet through the lower winding of the relay 719, the vertical test brush 712, the wire test gauge, earthed, to which it is engaged and the starter wire 411.

   Relay 719 attracts in the circuit of -

  <Desc / Clms Page number 50>

 blocking of the ascent electromagnet. 709 and closes, at its upper internal contacts, its blocking circuit by means of its upper winding; it disconnects the brush L from group 700 at its upper contacts; at its end, it puts the lower output / ascent electromagnet 709 off and transfers the control circuit to the rotation electromagnet 710. The ascension electromagnet 709 returns to rest and allows upon releasing the relay 720, the rotation electromagnet 710 operates and advances the brushes 700 and 712 horizontally to the selected level.

   The operation of the rotation electromagnet takes place in conjunction with the attraction of the relay 720 as happened with the ascension electromagnet 709. It can be pointed out that the vertical broom 712 is brought in. outside the contacts of the vertical bench at the first rotating pitch. In this way the rotational movement which results from the interaction of the rotational electromagnet 710 and the relay 720 does not interfere therewith.



   The rotational movement continues until the brushes 700 engage on the terminals of the calling line, in the present case the terminals 400 associated with the line circuit LC2 of FIG. 7. Recall that wire C of the LC2 line circuit is connected to a polarity which marks the line as calling, this polarity is supplied through the winding of relays 402 and 4C3.

   As a result, when the brush 0 of the finder FI of fig. 10 engages on pin C of group 400, the circuit of the top winding or test winding of the finder relay 701 closes through wire C of the line circuit LC2, the other terminal of the coil of the relay being connected to the grounded wire 718, By attracting, the relay 701, at its inner upper spring, closes the circuit of its middle winding, while at its spring

  <Desc / Clms Page number 51>

 lower, it immediately opens the circuit of the rotation electromagnet 710 to stop the rotational movement, the brushes 700 being engaged on the terminals 400.

   It also closes the blocking circuit of the start relay 702 through the upper winding of this relay and through the resistor 716; it switches on the negative and positive brushes, from group 700, it connects the 718 grounded wire directly to the associated brush C, thereby placing a direct guard polarity on the C wire of the LC2 line circuit in the aim of keeping the line circuit effectively against any untimely commissioning which could be carried out by other researchers and with the aim of providing a direct circuit to relay 403 of the line circuit L02.



   In the line circuit LC2 the relay 403 attracts, through the intermediary of the wire C which is associated with this circuit, when the searcher stops on the terminals 400. By attracting, the relay 400 closes its own blocking circuit at its lower internal contacts without the aid of the contacts of the starting relay 402; it turns off the group call light; it removes the earth from the starter wire 411; it releases the relay 402 by transferring its upper winding from the upper winding of the starting relay 402 to the EC wire; he places the left windings of the translator coil 430 on the wires of the incoming junction circuit IT, thereby indicating to the public office, following the closure of this direct current bridge, that the call has been answered in the adjoining office.



   In the FI seeker of fig. 10, when the circuit of the rotation electromagnet is open at the lower contacts of relay 701, the blocking circuit of relay 719 is open, relay 719 releases. When it releases the relay 719 places on the brush L a positive taken from the contacts of the relay 703, it closes the circuit of the iden-

  <Desc / Clms Page number 52>

 IL2 of position 1 through terminal L of group 400. This lamp lights up to identify the group in which the line to which the finder FI has been connected is located. The IL2 lamp is common to all incoming junction circuits such as IT, as it is multiplied to the L wires of all terminals, such as 400 of the FI researcher bench, which terminate line circuits such as LC2.



  The wire L which ends at the terminals L of the group 4CO, contrary-. ment to what happens for the other wires which go from the LC2 line circuit to the terminals of group 400, is not multiple in the researchers' banks associated with the other three operator positions as indicated by the absence
 EMI52.1
 a s.oole of cOnl1exioLcomm on wire L adjacent to the terminal shown on the plan. The multiplication between the nine seekers associated with the same positions is assumed to be allowed and is therefore not represented. It will in fact be understood that each of the other positions is provided with an identical lamp, the lamp IL2, which serves as an identification lamp when one of the researchers of another position finds a line circuit such as LC2.

   The identification lamps ILI, IL3, IL4 have a function similar to that of the identification lamp IL2, each separate group of lines having its own identification lamp, at each of the positions, which lights up when any of the rows in the group are found by the finder. It will be noted that the blocking circuit of relay 7C2 '-, through its upper winding, closes to the contacts of relay 701 and includes resistor 716. This resistor is provided in the first place to allow the starting relay 702 to be short-circuited and therefore for it to release under the control of the position equipment.



  For this purpose the release wire 726 (cable 1) is connected through contacts of relay 703 at the junction point of the upper coil of relay 702 and resistor 716.

  <Desc / Clms Page number 53>

 



   The conductor 726 extends until contact with the release key of FIG. 27. The release wire 726 is used to pull the relay 2110 as soon as the blocking circuit of the relay 702 closes when the relay 701 attracts; the lower winding of relay 2110 now being connected in parallel with resistor 716. When relay 2110 attracts it opens the circuit described previously for the attraction of relay 2112.



   The starting relay 2112 is delayed on attraction as can be seen on the plan, it remains attracted for a short time when its circuit is already open. Relay 2110 also closes the pull circuit of relay 2105 through contacts of the attracted relay 2112 and through wire 2124 and the contacts of relay 2107.



   When relay 2105 attracts, it disconnects the equipment of the operator's station from the head and neck conductors.
728 'and 729' and extends them to the common tone and call wires 2143 and 2144 which come from the secondary winding of the call tone transformer shown in the drawing. A distinctive tone is therefore transmitted through the contacts of the signaling relay 2105 and the contacts of the operated relay 2104 to the attendant receiver.



   This receiver is associated with the secondary windings of the induction coil I in an anti-local effect circuit which includes the artificial line AL.



   Relay 2104 attracts relay 2106 which cuts off the call tone current at its upper contacts and at the same time closes the circuit of relay 2107. Relay 2107 draws in and reapplies ring tone current. call to its upper contacts, it blocks' at the same time on wire 2124 and opens the circuit of relay 2105. Relay 2105 releases after a certain time and therefore stops the application of the two current pulses of call tone ...



   Relay 2107 remains stuck in wire 2124 circuit until

  <Desc / Clms Page number 54>

 which delayed relay 2112 releases, causing relay 2107 to release.



   When relay 2112 releases it disconnects wire 2033 from wire 727 but this has no particular effect for the moment because the upper winding of the starting relay 702 of the FI finder is now incorporated in the blocking circuit which has been described previously. Relay 2112 also removes ground from wires 2031 and 2032. Therefore relay 2025 releases and relay 2021 also releases unless the distributor start wire is set. the earth at another position; in this case it remains attracted and the distributor proceeds to the preselection of another position.



   When the sending of the call signaling current to the operator's receiver is finished, the latter can immediately converse with the subscriber of the public office via the head and neck wires 729 'and 728' , wires 729 and 728, relay contacts 2125, head and neck, response wires 724 and 722, FI finder positive and negative wires, and pickup relay contacts 703.



    At this point it can be observed that the seeker FI being the answer switch and the selector FS1 being the call switch, the wires and all the equipment relating particularly to the seeker are called answer wires, while the wires wires relating particularly to the portion of the connection circuit which is under the control of selector FS1, are called call wires. The attendant of the annex office serving position 1 therefore converses via the incoming junction circuit IT of the freeze 7 with the subscriber of the public office. It will be assumed, for greater convenience, that the subscriber of station 1 of the annex office of FIG. 16 is the one we ask for, his. number being 91225.



   After making sure the number 91225 is

  <Desc / Clms Page number 55>

 the desired number, the operator dials this number using the transmitter - recorder selects by operating the DL digit keys of the wire -. 29.



   Selection of a free transceiver.



   The way in which the selection of a transmitter = free recorder is carried out will be described below. As mentioned above, the operator serving position 1 has two transmission circuits for its exclusive use; these are the circuits SLI and SL2 of figures 28 and 29. These transmission circuits have access by means of connection circuit seekers LF1 and LF2 to each of the nine connection circuits of position N 1 of which the finder is a part. FI of fig. 7 and the FS1 selector in fig. 8. These transmission circuits also have access by means of the secondary selector SSI and SS2 to a group of transmitter selectors which are intended for the common use of all the operators.

   The sequence relays 2201 and 2202 operate automatically to switch on the connection circuits SL1 and SL2 alternately.



   Returning now to the point where the relay 2110 attracted as a result of the switching effected by the researcher FI we see that the relay 2110 extends the positive up to the starting wire 214.1 of the junction circuit and through the contacts relay 2111. Assuming that both relays 2201 and 2202 are in the off position when wire 2141 is grounded, the circuit of relay 2202 closes through contacts of relay 2201. Relay 2202 therefore attracts and closes its circuit. blocking at its inner lower contacts through contacts of key 2203 and through the lower winding of relay 2101.

   This blocking circuit comprises the guard wire 2142 which is earthed to the contacts of relay 2101 as long as the operator has her microphone and her receiver inserted in the jacks provided for this purpose and as shown on the plan. . The

  <Desc / Clms Page number 56>

 relay 2201 however does not intervene in this circuit for the moment because its lower winding is shunted by the earth given by the relay 2202 in its initial circuit.



   When relay 2202 is attracted and relay 2201 is at rest, relay 2205 of the transmission circuit? 1 attracts, through the contacts of relay 2207 and puts the connection circuit into service, therefore the junction circuit finder LF1 searches for the preselected circuit and the secondary selector SS1 searches for a free transceiver as will be explained below. -after.



   When relay 2205 pulls it closes the circuit of switching relay 2208 in series with the control electromagnet 2210 through the tere taken at contacts of relay 2207 and through contacts of relay 2206.



  In addition, it connects the junction point of the switching relay 2208 and the control electromagnet 2210, through the contacts of relays 2203 and 2207, to the test brush 2212, thereby relay 2208 is bypassed. and the control electromagnet 2210 functions as a buzzer to advance the brushes 2211 (in the case where the transmitter-in-ie register on which the brushes are engaged is occupied whose test contact is therefore earthed)
 EMI56.1
 until a free transmitter-en6Jistrevx is found.



  * When a free transceiver is found (the RS transceiver of fi. 20 for example) relay 2208 attracts since it is no longer short-circuited, it disconnects test brush 2212 from the test circuit and connects it to earth; It thereby grounds the grasped transceiver test lead 2312 to mark it busy.
 EMI56.2
 



  Relay 2205, in W tt; af2t yferr e moreover the circuit of the pol.ris -'- T-cn o.a cEroEler :: and lower winding of relay 2204; it applies -UI positive to the test winding

  <Desc / Clms Page number 57>

 of relay 2204 to allow it to test the pre-selected connection circuit, finally it closes, through contacts of relay 2204, the circuit of control electromagnet 2209.



  The electromagnet 2209 operates like a buzzer to advance the searcher brushes of the LF1 junction circuit. This operation continues until the brushes reach the group of terminals associated with the junction circuit which consists of the finder-finder of pin 10 and the selector of fig. 12. This connection circuit was preselected when the conversation key K2 was activated. At this moment the brush C of the connection circuit finder meets the marking negative placed on the wire C of the group leading to the preselected connection circuit of fig. 10 and 12.

   This marker negative was placed on the C wire in question when relay 703 drew; it is brought through the contacts of relay 708, wire C of selector FS1 in fig. 12 and the engagement contacts 810 of the selector as well as through the upper coil of the relay 805. The selector relay 805 attracts when the brushes of the IF connection circuit finder arrive / on this circuit but it does not has no particular effect at this time.



   In the transmission circuit SL1 of fig. 28 relay 2204 attracts in series with relay 805 of the selector through brush C and the wire C which is associated with it. By pulling the relay 2204 opens the circuit of the control electromagnet 2209 to stop the search and it closes through contacts of the relay 2208 the power supply circuit of the modeling lamp 2211, which indicates to the operator that she can start dialing the requested number. It will be understood, however, that these operations are absolutely finished before the operator has been able to receive the necessary information which the calling subscriber must give her.

  <Desc / Clms Page number 58>

 



   Relay 2204 also closes the three files, remaining in the group of six, associated with the operator key group, the first three having been switched on when relay 2208 attracted. The wires A, B, C and D which come from the keys of numbers DK are extended through the brushes 2216, 2215, 2214 and 2213 until the corresponding wire terminating
 EMI58.1
 1'-Transmitter-recorder Rà3 of fig. 3c <. This transmitter-recorder is ready 1 :, to operate by pulling relay 2301 of the transmitter control circuit, which pulled through test lead 2212 (grounded as it was.
 EMI58.2
 explained above when the transmitter is put into service).



  It and to the ground the wires 2326 and 2324 going towards 110 transmitter-recorder PIS. This 3mitter-created :: istre - :: cr is of the known type, its operation will not be described in detail. iiise in service and at ± niar; aµe of 1 '± r; ette. = - r-enr4istrcur.



  When the operator nanipulates the DI keys of the fiS. 29 to cosipce the 1 '!' 9122? the figures are collected by the auuetfeur-eni4zistrenr of the known nose and the guard relay 23C4 of the control circuit of the transmitter shown in fig. 30 attracts when garden wire 2325 is grounded by the transceiver, which occurs when the first digit has been registered. This relay remains attracted
 EMI58.3
 ltis = ßz 'w what the number ci; l.istré at .iti ccnpietement re t = c sis; as such, wire 2325 is no longer connected to earth through the RS transceiver.



   In the event that the operator notices that she has
 EMI58.4
 cc: ¯s an error in eniF2l &; :: t the number keys, it pellet cancel the game or., '' J -: '': 1 '' 'yes c. : t. enrf .. '' 1s i; r :: 2 until Lioment by activating the error key EU; this attracts relay 2306 of circuit a 1 b.3zicn SL1. Relay 2306 opens the circuit of relay 2208 which releases and releases the transmitter.
 EMI58.5
 tor-en1'ûstreur QZ er ¯ "; ''. ¯.c¯: üât the rel = # is 230 .. When the rI :.: .- <.1.S <::. :) .0 can r -, - ", = # r '.-,;.

   J..ú -'J -. - J -.> - "" u "of 1 key

  <Desc / Clms Page number 59>

 error in normal position, the transmitter of fig. 30 is entered again (unless it has been entered in the meantime by another, selector. In this case another transmitter is entered) and it is ready to operate again.



   When the attendant has counted the number requested, she activates the start key ST and thereby separates the circuit of relay 22C7 in the junction circuit SL1. Relay 2207 attracts and blocks. these internal contacts to a ground taken at the upper contacts of relay 2205.

   Relay 2207 also extends an earth through 'broom 2211
 EMI59.1
 up to wu's thread; .. rr..Me 211, tai-dis fiL; ' its median spring it applies a direct positive to the test brush 2212 without the help of the contacts of the shine 2208, it opens at a point
 EMI59.2
 su.l - '..:' 1-: u8 "lt: .. irG the c¯.: û¯s: i search for the secondary selector.



  Relay 2207 also applies a direct earth to brush C of the LF1 connector circuit finder to place a pole.
 EMI59.3
 rit5 of jardc on 1 thread d =. 1 ". 'P, ..." ..0 ".. Cl' 6 it opens at the same tew ..? 3 the c ißcai t .16 :: rt, l; .. i. '; 22, A and 220. The 22CC relay relays: .. a 1 ..,. I ± à.iate = i #.> T 6t the l ':::; l1 ... i :::. 2G5 releases after a very short moment. Zn l '.: .. lS.c8.nt, lE .. relay 2205 e: i; re other opens the circuit of the garden windings and polarization of relay 2204-, which releases this one.

   2204 relays
 EMI59.4
 and 22cl as rel: cl ':' 81 the wires wsoci.sw GXLX keys of the DK digits are disconnected from the connection circuit SL1 so that the attendant can now use this wire for a subsequent call in connection with the circuit. SL2 connection.

   The starter relay 2207 {both attracts and the others
SL1 relay of the connekion circuit being released the brushes of
 EMI59.5
 test C and 2212 of C '::' -... üt:.:. te1..l1'S Lbl and 551 are put L the earth and the negative, positive and CT brushes of the LFI connection circuit finder are connected by the 'Intermediate contacts of relay 22C7 and contacts of relay 2203 to the corresponding brushes 2214 to 2218 of the transmitter selector SS1.

  <Desc / Clms Page number 60>

 



   In the transmitter control circuit of fig. The start pulse caused by actuation of the starter key, as explained above, and the resulting pull of relay 22C7, is received through starter wire 2312 in the winding top of relay 2302. Relay 2302 pulls in and closes. its blocking circuit as well as a guard circuit of relay 2207 through the winding of relay 2303 and the contacts of relay 2304-. The relay 2303, however, does not attract until the starting key SK in fig. 28 is returned to the normal position.

   At this point the shunt that previously existed on the winding of relay 2303 is removed and this relay can draw in series with the windings of relays 2302 and 2307. By pulling relay 2303 closes a similar guard circuit across the lower winding of relay 2302, this circuit also supplies the winding of relay 2207 in parallel with the upper winding of the
 EMI60.1
 rei.e.-8 2302 thus contributing. mainisnir ae3 relays attracted.



   At its upper spring the relsis 23c3 extends the earth through the contacts of the relay 23c4 to the wire
 EMI60.2
 start-up 2323 of the transmitter-reg.4jis% raur RS à6r - # rrc- # it thereby re-transmits the digits that have been stored.



  The retransmission of the stored digits is carried out through the negative and positive impulse wires 2321 and 2322, the contacts of the relay 2302, the wires C and B, the relays 2214 and 2215, the contacts of the relays 22C2 and 2207, the negative and positive brushes of the LEI connection circuit finder and the positive and negative wires of the connection circuit leading to the selector FS1 in fig. 11. The relay 802 of the FS1 selector draws conversation wires into the circuit.
 EMI60.3
 e11.t1.'9.; 1, ts and in the circujt: it:!.: ¯:;: vitiate, '' ",: 2. t '1 is question here -" "JS'3US as soon as 1s - .

   Fl ... ¯ "3 ': 2 nd. A -'.- pulls, retorts it is described above. When attracting, relay 8C2 closes the circuit

  <Desc / Clms Page number 61>

 relay 803. As a result, relays 803 and 804 attract and the selector is ready to operate. The preparation for the operation of the selector is carried out when the starting key is actuated as explained previously and before it is returned to the normal position to remove the shunt placed on relay 2303 and therefore to start the sending pulses.
 EMI61.1
 



  Release of the team,
As soon as the operator has started sending the pulses as has just been described, she can return the conversation key to the rest position and allow the equipment to be released from its position. When the conversation key K2 is returned to the normal position, relay 703 releases because its circuit is cut.

   Relay 703 disconnects the talk leads from the common position equipment connection circuit and reconnects the talk, answer and call leads together; it disconnects the position wires 725, 726 and 727 and it turns off the group IL2 identification lamp, the relays 701 and 702 remain energized and the latter maintains a ground on wire 718, which also maintains the 743 lamp on for the moment to indicate that the call has not yet been completed.



   In the positional equipment of fig. Relay 2104 releases when the talk key is lowered while relay 2110 releases when wire 726 is disconnected when connection circuit relay 703 is released. The positional equipment of fig. 25 is therefore in normal condition at the disposal of the operator who can serve another call. Ground is removed from wire 2141 when relays 2104- and 2110 release.



  As a result, the initial circuit of relay 2202 is open and the shunt placed on the winding of relay 2201 is removed,

  <Desc / Clms Page number 62>

 relay 2201 draws into the blocking circuit of relay 22C2 (through grounded wire 2141) which prepares the subsequent selection of the transmit circuit. SL2.

   In the circuit SL1 the lamp 2211 which was lit as soon as the switches LF1 and SSI had finished their selection operation remains on in the circuit which borrows the lower contacts of the relay 2207 and the resistor associated with it until that the RS transceiver has finished its operation but the lamp now burns with a dim luster because a resistor has been incorporated in its circuit, this indicates to the operator that pulses are in progress in the connection circuit.
 EMI62.1
 



  T-iberation of the transmitter-recorder and the transmission circuit.



     AS soon as the last recorded digit has been transmitted, the RS transceiver removes the earth from the guard wire 2325. When this occurs relay 23C4 releases and opens the circuit of relay 23C3 to allow the release of the control circuit. of the transmitter and the transmission circuit SL1. At the same time, relay 2304 closes this separate circuit through wire A which is connected to it and via contacts of relay 23C2 which is switched on by delayed relay 2303.

   This circuit continues through
 EMI62.2
 bclais 2316 and that of cores.1 - utatours SS1 and Him or through the CT wire. to relay 708. Relay 708 draws in the circuit which includes resistor 746.



  At its lower armature, relay 7C8 turns off the lamp and the connection has been established and it closes its blocking circuit and opens its initial attraction circuit. It also disconnects wire C, from the FS1 selector associated with it, from the branch accessible to the circuit chcrcheur
 EMI62.3
 of this; nejic-n and il 7 c 01: r> 9C + ('Icccleaent.'. earth; i- zez -'r- '"CO!: l +.! -'" 'v.¯. -' " , '-' ';' '"11' <, "0, -rc1r'C 1". , ..- i- "C '" l-it ëLe C / "' ['"' "r-

  <Desc / Clms Page number 63>

 station and at its upper inner contacts it extends the positive through contacts of relays 704, 705, 707 to relay 751 of time switch TS 'for a reason which will be discussed below.

   The release of the transmitter control circuit of fig. 30 and the transmission circuit SL of FIG. 8 is carried out following the release of relay 2303 which opens the guard circuit of relay 2302 and the blocking circuit of relay 2207 in the connection circuit SLI. The relays 2302 and 2207 therefore release and return the circuit they commanddnt to the normal position.



   When the transmitting circuit SL1 is released following the release of the relay 2207, the brushes of the transmitter LS1 are disconnected and the bridge placed on the positive and negative conversion wires of the connection circuit shown in figs. 7 and 8 is open. The connection that has been established is maintained through the attracted relay contacts 708 and. through the conversation wires of the finder F1 and the straight windings of the translator coil 430 of the line circuit LC2. The relay 704 has its lower winding connected in series with the negative wire of the connection circuit, it is shunted by a capacitor.

   The relay 704 does not attract until the subscriber has not answered because the current is flowing in the normal direction in its lower winding; its polarizing winding is fed via wire 717 through contacts of starter relay 707.
 EMI63.1
 Automatic speed after a determined time.



   Provisions have been made which allow the operator to automatically call back from the annex office at the end of a determined period of time in the event that. the called subscriber does not answer. How this service is performed will be described below. Or¯ previously reported that an earth was extended through the upper inner reinforcement

  <Desc / Clms Page number 64>

 from relay 708 and contacts of relays 7C4, 705 and 707 to relay 751 after pulling relay 708 at the end of the emission of the pulses. The relcis 751 is normally connected,

     through his own contacta, to the common thread
 EMI64.1
 75É 4th Pulse transmitter L teups 111. 1'lai ,, s pulse transmitter at time Tl un Xl-: Jze.tif 6Zt r.:rw.?le,,lcl1.t cC.clelected to wire 785 when the device is idle. Under these conditions
 EMI64.2
 the left winding of the releic 7Jl have so-LLs' temion through the wire 758, so the relay 751 pulls - and closes its blocking circuit through its two windings -
 EMI64.3
 series, - = 1 d'c, ... '1 t- ...., ....-, \: rt ents in series, it dscs-.nnectJ dcm 1 ". # f, - 1.-Éùlc of the wire 7-; 3.

   Relay 7? 1 connects the DC wire;.; : -. ù -6C: 1 1 '± lecira-c-, iiasRt te coxnva, nde 73 "3;: pC.ll' iYl - !; er; {di :: il'tS do bank contacts 5t d ' bal # "1 756 and he e m-, JeJsii '; iF x = ir i ± - fil ec d ± x; s, r- raj.cr 7? 9 and opens in midye: = pi in Lin; anointed, the circuit of 1 '± îsctrc-ai:> aut l = e li'o ± J.1àtiJn 7j2, iu, am; 1 the wire of d ± n; bridging 7? 9 is energized the circuit of the contact Read from relay 762 closes through contscts from relay 764.



  Relay 762 attracts but contact @@@@@ ié to the armature
 EMI64.4
 ballasted 3t r ± = 1 ± toc such z, g.-i 'il # -iEre for a period of about two fertile before 0L return to rest: C.Ul' perDett ::: - e au rolais 763 to attract . At the end of the period of two aùc = 'ii.flc #, relay Î6 "attracts and --rcrLe the circuit of relay 764. This draws and cuts off the oiro-.it of relay tïf..2 which restarts . i> = i # 'lr the release of relay 762 relays 763 and 764 successively connect (cl; ao; ui t them 6ta t rets; # G ± somewhat jjar continuation of the prince of.' 1 # ic "C 'a.:(.lE copper on its ncau). When relay 763 releases, it closes the circuit of the electromagnet
 EMI64.5
 of r = cùr; ¯ande 7 53 through the attracted contacts of relay 764.

   Ltlectro- & i.w8.l1.t 753 attracts and '? ¯C: 111 shunt at the terminals of the brush? 66 and of the bank contacts etc.

  <Desc / Clms Page number 65>

   associas to prevent the opening of its circuit while the brush is brought from one contact to the next. When relay 764 releases it opens the control circuit and again applies negative polarity to wire 758 to allow a relay, such as 751, to be picked up, associated with some other connection circuit to which the M time pulse emitter. He is assccied.



   It can now be seen that the brushes 755, 756 and 757 advance one step under the action of the electromagnet 753 each time the pulse generator in time performs a cycle of operations, which it does. done approximately every two seconds. Therefore after about 18 seconds the broom 757 will have taken nine steps and will reach its tenth contact. At this moment, the brush 756 engages on a neutral contact so that any advancement is canceled.

   The 757 brush extends the 751 wire to the 743 lamp which has been
 EMI65.1
 off before :::. lellt and causes it to come back on to indicate to the attendant that the communication she thought she had established was not successful within the prescribed time, the attendant can then activate her key conversation K2 and start a conversation with the calling subscriber in order to establish another communication to any line of the annex office, it being understood that in an annex office it is common practice for a subscriber to the public office of - requests information which can be given to it by several subscribers.

   How the communication is cut and re-established will be explained later.



   Usually the call is answered within a reasonable time; in this case the time switch TS of fig. It advances to the recall position and is released by the supervision relay 704.



     Establishing communication when the - /

  <Desc / Clms Page number 66>

 N 91225 is issued by the RS transceiver will be described below.



   When the first digit (9) is sent by the RS transceiver in fig. 30, the relay 802 of the primary selector FS1 releases nine times momentarily, so it sends nine current pulses to the ascending electromagnet 808, as a result the brushes 800 are brought in front of the ninth level. banks of contacts and that the spring 815 of level 9 is actuated to cause the absorption of the first digit as has been explained for the primary selector FS5 in fig. 16.



   When the selector FS1 returns to the normal position, the relay 806 draws in series with the releasing electromagnet 809 and locks itself at its upper contacts, thereby adapting the selector to the operation of a selector. regular without absorption of digits.



   When the second digit (1) is transmitted by
 EMI66.1
 the transmitter-recorder, the relay 806 momentarily releases once, it brings the brushes 800 in front of the first level of the contact bank. The operation of the rotating electromagnet. 810 is started when relay 805 releases and
 EMI66.2
 this movement continues up to this cyue ls bilai C G.u s: leeteur meets a n4getif on 13 thread C. f w. selector sst o = 1- free in group ^ 1, secondary selector SNS
 EMI66.3
 GS 1: trust. 22 for example. ce;.: #., :: t lc relay 8C5 attracts and returns the connection to the S'li .. ^. t ¯¯. '.' secondary input cc c-ui allows .relays 8C2 and 2C3 3 tt:

   the Ctear FSI to release.
 EMI66.4
 



  , nr c: i: treea t of the key e ca f :; 1 st API case: incoming key.



  At this point of expcse 7.1 it may be useful to explain how the 'C'2lr.f' is carried out. "1 ':' T: .a: ¯''t of the class in the lessons of incoming calls. Cl: must notice that the terminal; .¯ roup 400 on 1> r.uclf t =, J 'is eàiraz4 the broom of ysc = 1-

  <Desc / Clms Page number 67>

 Mination D, of the searcher brushes 7CO, is connected: earth while the corresponding terminals of groups 300, 500 and 600 associated with the other line circuits shown are neutral. As a result, the broom D of the FI seeker only encounters a ground if the call to be answered is an incoming call from the public office.



  By this arrangement, the relay 808 of the primary selector FS1 attracts only in the case where the seeker FI is put into service to answer an incoming call, as in the case which is described below. The relay 801 being attracted, a positive given by the intermediary of the upper contacts of the relay 803 is applied to the brush EC, of the brushes 800 of the selector FS1, when the relay 807 attracts as it has been said above.

   The application of a positive to the EC brush of selector FS1 results from the closure of the circuit of relay 805, recording of class, 2 through the EC wire of the secondary selector switched on SES. attracted
The relay 1805 / and is blocked in the circuit of its two windings connected in series in the incoming wire C. It thus registers in this way that the call in question is a call coming from the public office. It should be noted that the recording pulse transmitted by the selector FS1 is terminated after a short time interval due to the release of the relay 803 after the attraction of the relay 807.



   Under the action of the pulses of the train representing the third digit (2) of the request number, the secondary selector SLS operates as described previously and brought its brushes in front of the second level, it seizes a local connector of group 912. On can assume, as was said in the example described above, that the local connector LCC1 of FIG. 23 is the one that is put into service.

  <Desc / Clms Page number 68>

 



   In the current example the relay 1805 of the SES selector is pulled. As a result, an earth is maintained on the incoming EC wire from the SES selector by relays 1803 and 1805.



  Under these conditions the attraction of the relay 1806 results from the momentary application of a positive through the brush EC and the. EC terminal of group 1851 to the incoming EC wire of connector LCC1 in fig. 19.



   Connector relay 1907 draws through incoming wire C and through engagement contacts 1924. The 1907 relay is blocked across contacts of the 1905 relay. This relay pulled in the manner described when the connector was put into service.



   The pulse sent to the EC wire by the SES secondary selector ends as soon as the 1803 relay releases, which it does shortly after the 1806 relay is pulled.



   Under the action of the pulses of the train representing the last two digits 2 and 5 'of the requested number the ccn-
 EMI68.1
 the local-ector LOCH attracts corn-.e dco "it previously to bring its 1900 brushes in front of the desired level and to turn them in the field of the contacts until they are silted up on the terminals of the called line. The relay 1907 being drawn, the EC brush of the cornector is connected to the lower winding of the relay 1903 as soon as the relay 1914 releases at the end of the rotation movement. The relay 1908 attracts or not depending on the line called. can receive incoming calls or not.

   In the case which concerns us the line called is the line of the station A1 of the fix. 12. As this line is a '- full service line, the terminal on which the EC brush of the LCC1 connector is engaged is neutral instead of being connected c. earth as is the case for the corresponding terminal of a line 1 ,. limited service.
 EMI68.2
 This does the 1908 relay 1: '- t -'; i.rc pac c-4; 1 &. connection and-

  <Desc / Clms Page number 69>

 blit to the called line which is ringed as described previously.



   Means used to prevent establishment
 EMI69.1
 dë''coiu5IcaI5hs * 'enranes'' with lines I ± éETIGéFéµfEéIEf7
When the attendant inadvertently establishes an incoming call to a restricted service line; the connection cannot be made because the EC brush of the connector (LCCl connector in fig. 23 for example) meets an earth on the corresponding terminal of the called line.



  It should be noted that the terminal EC of the group shown, in which appears the restricted service line of station A2 in fig. 16, is connected to earth. All other restricted service lines also have a similar connection. Under these conditions when relay 1914 releases and relay 1907 is pulled, as stated above, relay 1901 draws and closes the circuit of the top winding of relay 1913 through contacts of relay 1908 , the upper armature of the 1905 relay and the earth.

   Relay 1913 causes a busy tone to be sent on the lower talk wire as previously mentioned, while the link is not possible because relay 1913 keeps one of the terminals of relay 1917 disconnected to prevent seizing. line.
 EMI69.2
 



  Recall of Ilop'ratricēpar¯ltabonii.6 from the public office.



   In the event that the called line is busy and the busy tone is returned to the calling subscriber from the public office or in the event that 1. ' operator has inadvertently made a call to a restricted service line, in which case the busy tone is also sent to the calling subscriber, the latter can immediately call the attendant back to the adjoining office without waiting for the recall period has elapsed. He performs this recall

  <Desc / Clms Page number 70>

 by manipulating its call dial which causes the emission of pulses which attract relay 401.

   By pulling at this moment, relay 401. closes its blocking circuit through contacts of relay 403 and through the EC wire, EC brush, finder F1, contacts of relay 706 and key contacts. K2 conversation switch and the 741 supervision lamp.



   The 741 supervision lamp comes on in this circuit and acts as a reminder signal from the attendant.



  When the attendant answers by activating the conversation key K2, she opens the circuit of the lamp 741 and the blocking circuit of the relay 401, which releases. The attendant can therefore cut off the established call and start the call again to another line in the manner described above.



   Assuming now that the called line is free, inrush current is sent in the normal way until the called subscriber answers.



   When the latter responds, the current flow is reversed in the incoming wires of the local connector LOC1 of fig. 23 by the retort supervision relay 1901, it was previously described in the operation of this connector.



   When this inversion takes place, relay 704 of finder F1 attracts and closes the circuit of relay 705. Rslais 705 attracts and prepares the circuit of relay 706. Note that the circuit of relay 751 is open when relays 704 and 705 attract. Therefore, relay 725 releases and disengages the time switch TS of the pulse emitter T1. The releasing electromagnet 751 attracts through contacts of relay 751 and the release contacts 754 to return the brushes 755. to 757 in normal position. As a result, the circuit of the release solenoid is open to engagement contacts754.

  <Desc / Clms Page number 71>

 
 EMI71.1
 Information call during an incoming call.



   In order to explain this characteristic of the local connector LOC1 of fig. 23, it will be assumed that the called subscriber of set A1 notices during the conversation with the subscriber of the public office that it is necessary for him to obtain some additional information, locally, before continuing his interview. In this case the subscriber of the set A1 establishes an information connection between his line and another line of the annex office, while maintaining the communication initiated with the public office.



   To send an information call, the subscriber of the set A1 momentarily activates the earthing button of his set which unbalances the circuit of relay 1926 of the LCC1 connector. The relay 1926 momentarily attracts and closes the circuit of the upper winding of the relay 1910, this one attracts at the first time and closes its blocking circuit through its two windings spoke in series.

   It becomes blocking / active circuit when relay 1926 releases and removes the shunt which was placed across the lower winding of relay 1910, this one draws, melts and transfers the called line of incoming wires from connector to. LS4 preselector in fig. 16. This preselector operates in the known manner. To turn on a primary selector a ground is returned to wire C to provide a blocking circuit through the top winding of the 1908 relay.

   The 1903 relay releases when the connection is transferred, but this operation has no effect at this time because the 1908 relay is kept drawn into the wire C circuit as indicated above to keep the 1905 relay drawn, while the Relais 1910 keeps 1901 attracted to prevent sending of the end signal to the operator serving the passage table.



   After the subscriber of the station called A1 of FIG. 16

  <Desc / Clms Page number 72>

 has put himself in communication with his local correspondent and has finished his conversation, he momentarily pushes the button on his set which again causes the 1926 relay to be momentarily attracted. At this moment, the 1926 relay closes the circuit of the Relay 1909 through contacts of relay 1910. Relay 1909 pulls and opens the initial blocking circuit of relay 1910 out by closing a new blocking circuit for itself, in parallel with relay 1901.



  As soon as relay 1906 releases, relay 1910 also releases, while delayed relay 1909 releases only a moment later. The 1903 relay attracts again as soon as the 1910 relay releases and removes the blocking of the 1908 relay as well as that of the 1901 relay before the 1909 relay has released.



   The conversation that had been interrupted with the calling subscriber from the main office can now be resumed.
 EMI72.1
 



  Transfer of incoming call to a second line.



   For the purpose of explaining an additional feature of the invention disclosed herein, it will be assumed that the abbreviation. ne notices / that the call should be passed to another subscriber in the annex office. Under these conditions and in order to remind the operator of the pass-through table, the subscriber of the Al station manipulates his call dial and for example emits the number 5, therefore the 1903 relay releases and attracts a certain number. of times. Relay 1908 remains pulled while sending these pulses because it is delayed on release but relay 1901 releases and pulls whenever the circuit is opened and closed by relay 1903.



  This operation causes a number of reversals of the direction of the current in the incoming wires of the connector.



   In the attendant connection circuit, shown

  <Desc / Clms Page number 73>

 in fig. 11, the momentary reversal of the current direction results in releasing and attracting the relay 704 of this connection circuit. The first time it releases relay 704 closes the circuit of relay 706 through contacts of relay 707. Relay 706 therefore attracts and closes its blocking circuit to its inner lower spring. As soon as the relay 706 attracts the supervisory lamp 741 is connected in parallel with the coil of the relay 705, thus the lamp 741 flickers while the relay 704 follows the pulses.



  When the pulse train ceases and the relay 704 pulls continuously the supervision lamp 741 turns on permanently and thus gives a reminder signal.



   When the attendant sees this signal, she activates her conversation key K2, which turns off the lamp 741, the circuit of which is cut on contact with this key. At the same time the connection relay 703 attracts in order to associate the connection circuit with the equipment of the operator position.



  This relay is powered, in a manner identical to that described previously, through test wire 733 contained in cable 3. At the contacts of relay 703, the earth is removed from the spring of supervision relay 704. and locking springs 706; the relays 705 and 706 therefore release.



   The ILS identification lamp in fig. 7 lights up in the circuit of wire L and through contacts of connection relay 703 to remind the attendant in which group the calling junction circuit is located.



   In the positional equipment of fig. 25 and 26, the relay 2110 attracts via the wire 726 and in parallel with the resistor 716 of the connection circuit; relay 2111 draws via wire 725 in parallel with supply resistor 746 associated with relay 708. Pulling these two relays sets the circuit of the equipment.

  <Desc / Clms Page number 74>

 of the position in accordance with the condition which currently exists in the connection circuit. Under these conditions an entertainment signal is applied to the connecting wires as a result of the attraction of the relay 2103 through the contacts of the relays 2111, 2115 and 2116, as will be explained later.



   After having entered into conversation with the subscriber called from the annex office and having taken note of the number of the subscriber to whom she must transfer the incoming call, ltop-. ratrice activates the release key K9 in fig. 27 to release the connection established in the annex office. The K9 release key pulls relay 2116 which disconnects the caller head and neck wires from the attendant set and from the answer end of the connection circuit, eliminating the troubles that are caused by the release of this connection. The release key K9 also places a ground on the wire 725 which bypasses the winding of the relay 708 and causes its release. When relay 708 releases, it opens its blocking circuit and again closes the circuit of lamp 743.

   In addition, it disconnects the earth of wire C of the selector FS1 and opens the conversation wires to allow the release of the established connection.



   When the attendant returns the release key to the normal position, relay 2116 releases as well as relay 2111 because relay 708 has been unlocked and there is no more current flowing through resistor 746 to give a voltage drop which keeps the 2111 relay attracted. With relay 2111 released, the warning discussed above is no longer applied to the line.



   With relay 2110 operated and relay 2111 released, the earth placed on wire 2123 by relay 2104 is extended to transmitter control wire 2141 to select

  <Desc / Clms Page number 75>

 again a free transmitter. It has already been pointed out that the sequence relays 2101 and 2202 are used to activate the circuits SL1 and SL2 alternately and when the functions of these relays have been described it has already been said that they draw in series to through wire 2142 after the transmitter has been used. In order to complete the description of the operation of these relays, it will be assumed that they are both attracted and that they are held in the working position through the wire 2142, the contacts of the key 2103 and the con- tacts. internal lower tacts of relay 2202.

   Under these conditions, the grounding of the control wire 2141 has the result of closing the blocking circuit of the relay 2201 through the upper spring inside this relay, while the earth is extended through the upper spring. median of relay 2101 to the junction point of relay 2202 and the resistor which is associated with it, therefore relay 2202 is bypassed, it releases and opens its blocking circuit.



   The relay 2201 being attracted and the relay 2202 released, the transmitting circuit SL2 is made active by the intermediary of the lower contacts of these relays, therefore the transmitting circuit SL2 operates as described above. now for the transmission circuit SL1.



   After having recorded the requested number, the attendant activates her starting key SK to start transmission, which is carried out as described previously.



  The establishment of the incoming call to the other subscriber of the annex office is therefore carried out using automatic switches.



   When the earth is removed from the control wire of the transmitter 2141, the relay 2201 releases preparing the pull of the relay 2202 for the next time the key to convert a free connection circuit is actuated.

  <Desc / Clms Page number 76>

 



  Warning sign.



  -----------------------
Provision has been made for the emission of a warning signal on the conversation wires in the event that the attendant activates her listening key to connect to a call in progress. since in the system described here, response supervision is not obtained for all calls, the application of the warning signal depends on the operation of relay 708. By this arrangement, in the case where the attendant activates again the conversation key of the connection circuit after this relay has attracted or in the event that it forgets to return this key to the rest position after this relay has attracted, the warning signal is sent on the line ; relay does not call until all digits of the requested number have been transmitted.



   In order to explain this characteristic, we will suppose that the operator wishes to leave his conversation key activated after the number has been completely sent by the transceiver in order to ensure whether the called subscriber is busy or not. The attendant usually works this way when the original call must have been made to another extension and she can assume that she will have to transfer it to a third line or back to the first subscriber who has. been called, if the second line called is busy.



   When the K2 talk key is pressed and relay 703 pulled, when relay 708 pulls, relay 2111 pulls into the circuit of wire 725, in parallel with resistor 746. When relay 2111 pulls, wire 2141 is not no longer connected to earth and the circuit of relay 2103 closes via contacts of relays 2115 and 2116. Relay 2103, by attracting, places a short circuit on its coil and causes its own release. This relay is

  <Desc / Clms Page number 77>

 provided with a conductive sleeve and a conductive ring as shown in the plan, which delays its operation in such a way that it gives a clocked signal which, although it is perceptible, does not disturb the conversation.

   Each time it attracts, relay 2103 closes the circuit which borrows the winding of the induction coil or the left winding of the translatrioe RC coil to end in the negative through the relay contacts. 2102 and resistance 2161.



  The elies produced by the closing and opening of this circuit are transmitted through the secondary windings of the induction coil IC in the conversation circuit, they are perceived in the operator's receiver as well as in that of the operator. subscriber calling from the public office. As soon as the called subscriber answers, he also hears this warning signal and he therefore knows that the operator is on a telephone call on the established link.



   The warning signal is sent only for the purpose of avoiding eavesdropping, however means can be made available to the operator which allow them to perform a transfer without causing this signal to be sent.



  Since the operator officially is only interested in the question of knowing if her call was successful or not and if the called subscriber answered, she can activate the cut-off key K3 to disconnect the answer part of the wire connection circuit. from its station and to separate the connection circuit in two, in this case the warning signal is not sent.



   When the K3 cut-off key is actuated, resistor R9 is bridged across the head and neck wires on the response side and the circuit of relay 2115 is closed.



   By pulling, the relay 2115 disconnects the answer head and neck wires from the call head and neck wires and the operator set wires, it extends these wires up to

  <Desc / Clms Page number 78>

 the resistance R9 via the contacts of the key K3 to maintain the existing bridge on them, this operation is not however required in this case. Relay 2115 opens the circuit that leads to relay 2103, which stops or prevents operation of that relay.



   If the called subscriber is busy, the attendant receives the busy signal. In this case, it can release the connection in the manner which has been explained previously by activating the release key K9 and by routing the call to another line.



   If it is assumed that the called line is free and that the called subscriber answers, the operator can enter into conversation with this subscriber and ensure that he is really the person for whom the call is intended.



   The operator can return the conversation key K2 to the rest position as well as the cut-off key K3, which places the connection circuit of FIGS. 10 and 11 in the conversation position and releases the position equipment of FIGS. 23 and 26.



   Normal release of an incoming call.



   --------------------------------------
How a successful incoming call is released will be explained below.



   It can be assumed that a communication has been established through the junction circuits of FIGS. 10 and 11, as described above, and the called subscriber hangs up his receiver at the end of the conversation. In this case the relay 704 releases and closes the circuit of the relay 706 through the contacts of the relay 705. The relay 706 attracts and places a ground on the second bank contact of the brush 705 which prepares the release of the connection after a time. about two seconds.

   Since relay 704 does not attract again for

  <Desc / Clms Page number 79>

 keep relay 705 engaged, supervision lamp 741 does not light up and relay 705 releases after a short time and extends the earth to relay 751, which causes the latter to be pulled across the relay. wire 758 to start the switch T1 and to place the time switch TS under the control thereof.



   About two seconds after relay 751 has drawn, a pulse is received through wire 760, as previously explained, causing brushes 755 to 757 to advance one step under the action of the electromagnet 753. These brushes are normally engaged on the first group of bank contacts and the first step brings the brush 755 on the second bank contact. This is earthed through the contacts of relay 706. Therefore earth is applied through brush 755 at the junction point of the upper winding of relay 702 and the resistor. 716. Relay 702 is therefore bypassed, it releases and opens the connection circuit.



   It should be especially noted that the switch T1 is arranged so that the minimum time interval is always introduced into operations, even if the switch is put into service by another junction circuit, since the earth is given by wires 751. During switch operation wire 758 is connected to negative only if relays 763 and 764 have released both, at this time wire 760 is disconnects at relay 764 contacts. When relay 764 attracts and opens this wire, it also opens the control wire; it follows that the relay 764 attracts and opens at another point the wire 758.

   Therefore the relays 762 and 763 successively release and a pulse is sent through the control wire 760, but the wire 758 always remains open and will not be closed until the im- /

  <Desc / Clms Page number 80>

 control pulse is complete. By this arrangement after a pulse has been received to operate a relay such as 751, a control pulse is not received through wire 760 until the full operating time interval of l 'switch has elapsed.



   When the relay 702 releases as stated above, it opens the circuit of the relay 701 at its lower spring and closes the circuit of the release solenoid 711 through the engagement contacts. 713. Relay 701 releases and disconnects the negative and positive brushes while the electromagnet 711 operates to return the brushes to the normal position. As a result, the engagement contacts 713 open the circuit of the release electromagnet. Removing ground from wire 718 by relay 702 also results in releasing relay 703. As the connection made in the adjoining office was maintained by the flow of current through the conversation wires through the winding right of the translator coil 430, this connection is therefore released.

   The relay 807 of the primary selector FS1 releases when wire C is no longer connected to the earth, it closes the circuit which, through the engagement contacts 817, causes the selector to return to the normal position under the action. of the release solenoid 809. the identification lamp 742 goes out when the earth is cut from the wire 717 by the relay 702; the operator is therefore informed that the junction circuit is available for another use.



   Removing ground from finder wire 718, as previously described, also removes ground from finder brush C and therefore from lead C of connection circuit LC2; thereby the circuit of the lower coil of the relay 402 and the circuit of the relay 403 are open.



  Relay 402 immediately releases but relay 403 does not

  <Desc / Clms Page number 81>

 loose only after a while. When the relay 402 releases, it opens the loop of the incoming wire with its internal upper spring; it also disconnects the relay 401 from the bridge formed by the incoming wires to prevent unwanted operation of this relay which could be caused by the release operations which are carried out in the public office. After some time relay 403 releases again and prepares the blocking circuit of relay 401, it again bridges the lower winding of relay 401 to the incoming wires.



   Opening the bridge to the interior top contacts of relay 402 gives end supervision in the public office.



   Call to a remote annex office.



   -----------------------------------
The way in which a call is made to one of the remote annex offices and which forms a separate part of the system in question will be explained below. This remote annex office can be a manual office or / automatic annex office where an operator sits. It is connected to the side office described here by trunk groups which vary in size from one to ten trunk circuits.



   As has been said previously, the lines which terminate at the remote annex office are accessible from a group of connectors to which one connects by sending the digits 9 and 9, one of them being the connector BC of FIGS. 3 and 18.



  As shown in fig. 3, the line circuit LC4 (which is the junction line between associated annex offices) is reached from the connectors by junction 1451, it has been shown that it is generally accessible from any of the first three levels of the TC and BC connectors while that by its fourth level the TC connector has access to the interurban lines which are not connected in the banks of the BC connector since it is desired that the operator establish the interurban communications.

  <Desc / Clms Page number 82>

 



   In order to (Explain the operation of the equipment of the annex office when calling a trunk line between annex offices, it will be assumed that the subscriber of extension A2 in fig. 16 wishes to be placed in relation to a subscriber of the annex office, 9931. To do this, the subscriber of set A2 picks up his receiver and sends the? 9931.



   When the receiver is picked up, the calling line is automatically extended to a primary selector, the primary selector FS5 being one of them. This selector operates as described here under the action of the first digit (9) emitted. It returns to its normal position automatically when this digit has been sent and is ready to operate under the action of the second digit (9).



   When the second digit (9) is emitted, the selector does not return to the normal position but rotates in the manner previously described to select a free junction circuit since the relay 1205 has drawn and has prepared the normal rotation of the selector on the ninth level, for the moment when the second digit (9) is transmitted. If we assume that the connector BC of fig. 18 is the first which was found free when the selector FS5 searched in the ninth level, a polarity indicating that this device is free being normally applied to the wire C of the connector BC via the upper coil of the relay 1403, engagement contacts 1415 and key 1419. Relay 1403 attracts.

   Note that the Group 1400 EC terminal is not used as it is not necessary to have an EC wire for calls that are routed through this switch.



   The relay 1401 of the BC connector draws in the. loop incoming conversation wires and terminate relay 1402 circuit; this attracts and prepares the operation of the connector, at the same time it places a blocking earth on the incoming wire C.

  <Desc / Clms Page number 83>

 



   When the tens digit (3) is emitted, the relay 1401 releases momentarily three times, each time it closes the circuit of the ascending electromagnet 1411 through the contacts of the attracted relays 1402 and 1403. The electro- Ascent magnet 1411 raises the brushes 1450 to opposite the third level of the bench contacts. The relay 1403 is kept attracted during the entire upward movement, at the end of it it releases and transfers the control circuit to the rotation electromagnet 1412.



   When the last digit (1) is output, the pulse sent by relay 1401 passes through contacts of busy test relay 1405, relay 1406, and contacts of relay 1410 to end up in the control solenoid. rotation 1412.



  The rotating electromagnet attracts and engages the brushes 1450 on the first group of third level bank contacts which is assumed to be the group of contacts from which the junction circuit 1451 is directed to the IBX line through of the LC4 line circuit of fig. 9.



   Relay 1406 attracts and causes relay 1407 to attract.



  The relay 1407 connects the brush C of the connector to the relay 1405, it prepares at the same time the circuit of the relay 1408.



   In the event that the first junction circuit of the group is busy, relay 1405 pulls when the brushes stop.



  Under these conditions when the relay 1406 releases, it disconnects the relay 1407, which has remained attracted in parallel with the rotation electromagnet 1412; at the same time it connects relay 1408, through the contacts of electromagnet 1412 and relays 1406 and 1405, to brush S. The contacts on which the brush S advances are connected to wire C the associated junction circuit; it follows that the earth placed on the wire C of the occupied junction circuits is transmitted by the brush S to attract the relay 1408.

   Relay 1408 at -

  <Desc / Clms Page number 84>

 pulls and closes its blocking circuit at its upper levels, at its internal contacts it closes the circuit of the rotary magnet 1412 to cause the brushes to advance by one step, this circuit also extends to to the auxiliary relay 1407 to keep the latter attracted and therefore to keep the relay 1405 connected to the brush C. The relay 1408 releases when the rotation electromagnet 1412 operates; therefore the circuit of the rotation electromagnet opens.



   The rotational movement continues through the interaction of relay 1408 and electromagnet 1412 until a free line is reached in the desired group or until the last line of this group. Following the usual practice, in the grouped lines the connection of one to the other is removed at the last line of the group which stops the rotational movement when one arrives at this last line, even if this one is occupied. . Under these conditions, relay 1405 remains attracted but auxiliary relay 1407 (which has been kept drawn in parallel with the rotation electromagnet 1412) releases. On release, auxiliary relay 1407 closes the blocking circuit of relay 1405 through the middle upper contacts of relay 1407.

   Relay 1405 is therefore locally blocked and it is disconnected from brush C of the connector. Relay 1405 keeps the rotation electromagnet circuit open at its lower contacts to prevent further operation in the event that the calling subscriber again acts on his call dial, while at its upper contacts the wire common 1417 busy is connected to the conversation wire to send the busy tone to the calling subscriber.



   We can now assume that line 1451 is free when the number is sent, as described above, in which case relay 1405 is not drawn. Under these conditions when relays 1406 and 1407 release, the latter connects the

  <Desc / Clms Page number 85>

 relay 1409 between the earth of the upper contacts of relay 1402 and brush C. As a result, relay 1409 draws in the circuit of wire C. Relay 1409 closes the circuit of relay 1410; this one attracts and switches on the brushes negative and positive. At this time the negative brush is connected to earth and the positive brush is connected to the common wire sending the inrush current to the upper contacts of relay 1404 which drew when the connector was put into service. In this way the inrush current is sent as soon as the relay 1410 attracts.



   This sending is also completed as soon as the relay 1410 releases.



  Stop capacitor 1418 allows inrush current to flow to the calling line to indicate that the call has been successfully completed. The relay 1410 also disconnects the rotation electromagnet 1412 as it prepares the circuit which will make it possible to recall the operator from the remote annex office.



   In the LC4 line circuit of fig. 9 When the junction circuit 1415 is grasped, as said above, the relay 602 draws through the incoming wire C and the inner bottom armature of the relay 604. By attracting, the relay
602 switches off relay 604 and prepares the attraction and blocking circuits of relay 603.



   When the inrush current pulse is received from the connector through the junction wires 1451 the inrush current is transmitted through the translator coil 630 on the conductors going to the manual office to trigger the normal calling devices.



   When the operator of the manual office answers, relay 601 attracts and closes the circuit of relay 604. Therefore this relay attracts and locks to its inner lower spring.



   The conversation can start with the operator at the remote office, who establishes the requested connection in the usual way.

  <Desc / Clms Page number 86>

 



   Call back from the operator of the remote annex office.



   -----------------------------------------------
If the subscriber calling from set A2 wishes to call back the operator of the remote annex office, he sends a number using his call dial. The relay 1401 of the connector of the annex office momentarily releases one or more times.



  Each time it releases it closes the circuit of the lower winding of relay 1403 via contacts of the attracted relay 1402 and the lower armature of the attracted relay 1410. With relay 1403 being attracted as well as relay 1410, each time the line relay 1401 attracts again at the end of a pulse, it closes the temporary attraction circuit of relay 1401, in parallel with relay 1403, to send the inrush current to the line junction called for the purpose of giving supervision. The recall device described above has been arranged in the manner shown in the plan so that it depends on the attraction of relay 1402, in order to prevent an untimely attraction of relay 1404 when the receiver of the station is hung up. appellant.

   When the calling subscriber hangs up his receiver at the end of the conversation, the relays 1401 and 1402 of the BC connector release. Relay 1402 removes ground from incoming wire C to allow the preceding switches to return to the normal position. Relay 1402 also unlocks relay 1410 to release line circuit LC4 of fig. 9. The release solenoid 1413 attracts through the engagement contacts 1414 to return the apparatus to the normal position. Therefore, the circuit of the release electromagnet is opened at the engagement contact 1414.



   In the LC4 line circuit the relay 602 releases when the connector is released as described above.



  The relays 601 and 603, however, remain attracted until

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 the operator of the manual office cuts the established connection.



  When relay 602 releases, relay 604 draws through the lower contacts of relays 601 and 602 and places a protective earth on wire C of group 1451. The circuit is not placed in the state it is at. moment when. a searcher starts because relay 803 remains attracted through its lower inner contacts and those of relay 601.



   When the attendant at the office leaves the connection, relays 601 and 603 release.

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   Incoming call from a remote annex office.



   The manner in which incoming calls from remote branch offices are routed will be described below. For this purpose, it will be assumed that the interconnection line associated with the LC4 line circuit of Fig. 9 is put into service at the remote annex office.



   When the line operated in both directions and associated with the LC4 line circuit is put into service at the remote annex office, the relay 601 attracts and closes the circuit of the relay 604 through the contacts of the relay 602. The relay 604 closes the circuit of the group call lamp GC4 from position 1 and that of similar call lamps from the other positions; it places an earth on the starter wire 611 to start a finder; it connects the wire C associated with the terminals 600 of the finder to the coil of the relay 602 to mark the line circuit LC4 as calling; finally, he disconnects wire C from local junction circuit 1401 from relay 602 and connects it to earth; therefore it keeps the line from being switched on by the connectors of the local annex office.



   When the LC4 line circuit is found in a finder (through terminals 600. Or multiples thereof} relay 602 draws through wire C and contacts of relay 603 and energized relay 604 When attracting, relay 602 blocks directly at wire 0 associated with the finder, it disconnects relay 604 at its lower spring and closes the attraction circuit of relay 603. Relay 604 releases and relay 602 pulls, from as a result, the circuit is no longer able to start the searchers and the GC4 group call lamp goes out.

   The identification lamp Il4 in position 1 (assuming the line circuit has been found by

  <Desc / Clms Page number 89>

 a finder in position 1) lights up in the circuit of the wire L which is associated with it and which appears at position 1 only, identical wires being provided at the other positions for the lamps identifying these.



   After the connection has been established, the switches of the local annex office are held in the loop which includes the straight windings of the translatrioe coil 630.



   The established connection is automatically cut off by the action of the supervision relay (relay 704 of the junction circuit in fig. 11) in the event that the call is answered, while the connection is cut under the control of the local operator, as has been indicated above, in the event that the called line is busy or if the called subscriber does not answer.



   In the event that the trunk line is released at the left end, before the established communication is cut off, relay 601 releases, but relay 602 remains engaged and keeps relay 603 engaged. The junction circuit is therefore kept locally and the new attraction of relay 604 is prevented in the event that the line is brought back into service at the remote annex office.



   In the event that the established connection is cut, before the junction circuit is released to the remote annex office, relay 602 releases but relay 603 remains blocked through its lower inner contacts and the lower inner contacts of relay 601. In these cases conditions the 0 wire associated with the finder's 600 terminals is disconnected at the upper contacts of relay 602 to prevent the LC4 line circuit from being marked as being

  <Desc / Clms Page number 90>

 calling in the researchers' benches, but removing the ground from wire C of the wires associated with the finder terminals 600 and releasing the resulting relay 602 removes the guard polarity of wire C of group 1451; therefore the junction circuit is made available for local connectors.

   By this arrangement the line can be seized before the connection is cut by the operator of the remote annex office, this arrangement was taken to accelerate the service during the hours of heavy traffic. When relay 601 releases under the conditions listed above (while assuming that the junction circuit is not seized locally at the same time) relay 603 releases and returns the line circuit to normal condition.



   Call offer to a busy line.



   Although as a general rule a conversation in progress should not be disturbed in the case where the called subscriber is already on a call, it is nevertheless desirable to provide the means of establishing an urgent call with a line. busy. For this purpose, devices have been provided, controlled by the operator serving the transit table, which allow the latter to establish a special connection to a busy subscriber in order to offer him an urgent call.



   In order to explain this feature, it will be assumed that the subscriber of the set A2 of figs. 3 and 16 sent the number 91225 assigned to station A1 in fig. 16, but it was not possible to obtain the requested communication because station A1 is busy. It will also be assumed that this call is urgent and that the subscriber wishes the call to be offered to his correspondent. Under these conditions, the subscriber of set A2, when he hears the busy tone, hangs up his receiver to free the

  <Desc / Clms Page number 91>

 switches that have been put into service, picks up his receiver again and transmits the operator's number (97) and asks him to establish the connection for him while he is on the line.



   If we assume that the primary selector FS5 is the one entered when the receiver was picked up, this selector works when the number 9 is transmitted and falls back in the manner which has already been explained. Then it raises its brushes to the 7th level when the second digit (7) is emitted, it rotates its brushes in the field of the 7th level contacts to search for a free service circuit.

   It will be assumed that the service circuit (fig. 6) which comprises the wires 301, 302 and 303 which connect the banks of the primary selectors to the line circuit LC1 of fig. 6 is the first which has been found free and that it is therefore this which is entered by selector FS5. when put into service the relay 304 draws in the circuit of the calling line, through the brushes of the selector FS5, and closes the circuit of the relay 305, The relay 305 pulls the relay 306 and also places a guard polarity on the incoming wire C to keep the connection established.

   Relay 304 connects through contacts of relay 308 the incoming negative wire to the common wire carrying the inrush current through a low capacitance shutdown capacitor, which simulates the operation of sending the inrush current that normally occurs on a called line. Relay 306 earths the starter wire 311, through the contacts of relay 308, in order to start a finder looking for line LC1, it closes the circuit of the lamp. group call Freeze from position 1 via relay 308, it also closes the circuit

  <Desc / Clms Page number 92>

 corresponding lamps of the other positions. As a result, the operators are informed that a call is pending and comes from a subscriber of the local annex office.

   Relay 306 also connects the C wire associated with finder terminals 300 to the top winding of relay 308 thus preparing the pull of relay 308 and marking the LC line circuit as calling in the seeker banks.



   The start relay 2001 in fig. 24 draws into the circuit of one of the wires 2000 and the contact of the vertical bench, associated with the appropriate level, is earthed, in each of the researchers such as the FI finder of Fig. 10, when the starter wire 311 is grounded as mentioned above. It can be assumed that the search engine F1 in fig. 10 has been preselected by the operation of the conversation key K2 and the attraction of relay 703 of the connection circuit, as well as by the attraction of relays 2204 and 2212 of the equipment of the operator and the distributor in fig. 24. The pulling of relay 2001 closes the circuit which was previously described for the starting relay 702 of the researcher Fl.



  Seeker F1 therefore operates in the manner described above to first raise brushes 700 to face the calling level and to rotate these brushes in this level in search of the calling line circuit. When the line circuit LC1 is found, the relay 701 draws through the brush C which is associated with the line circuit and in series with the upper winding of the relay 508 of the line circuit LC1, to stop the search operation. finder and to enter the line circuit. Relay 308 closes the circuit of its lower winding through the lower internal contacts of relay 305, at the same time it opens to

  <Desc / Clms Page number 93>

 its upper contacts the connection through which the ringback tone was transmitted previously.



  Relay 308 also disconnects the resistor associated with wire 0 303 coming from the selectors; it switches off the group call lamp GC1 and the corresponding lamps in the other positions, it removes the earth from the starter wire 311 to allow the release of relay 2001 unless another call has occurred in the meantime.



  In the finder F1, the attraction of the relay 701, when the line circuit LC1 is found, causes the closure of the blocking circuit of the upper winding of the starting relay 702 via the resistor 716; the subsequent operation is identical to that which was described previously and will therefore no longer be recalled here.



   When the operator talks with the calling subscriber and is warned of the urgency of the requested call to a certain number, she manipulates the DK digit keys in fig. 29 to dial the requested digit which will be retransmitted. . When the digits of the requested number (91225) of the line of station A1 in fig. 16 are sent, the automatic switching devices operate, as described previously, to establish communication to the line of station A1. it is assumed that the line of the station A1 is still occupied, the relay 1913 attracts when the brushes 1900 stop on the terminal of the called line and 11 is blocked when the relay 1915 releases.

   Busy tone wire 1943 is now connected through contacts of relays 1913 and 1912 to the talk circuit to transmit a busy signal to the operator and to the calling subscriber. Since she has been informed of the urgency of the call, the attendant keeps her call key pressed to stay tuned.

  <Desc / Clms Page number 94>

 



   In order to connect to the busy line, the operator activates the K6 offer key in fig. 27. The offer key K6 closes the circuit of relay 2115 in order to disconnect the calling line for the moment and to stop the operation of relay 2103 which has started to beat as described previously, as soon as the relay 2111 attracts after the transmission of the last digit and after the attraction of relay 708 in the connection circuit of fig.ll. The K6 offer key also closes the circuit of relay 2113 and at the same time places a polarity on the emergency call wire 732 through the contacts of relay 2113. A pulse is therefore transmitted on wire 732 for the time required to the attraction of the 2113 relay.

   This pulse passes through the wire 732 and the contacts of the conversation key K2 to end in the wire EC entering the primary selector FS1. The pulse is transmitted through the EC wire, the EC brush from the FS1 selector to the secondary SES selector and from there through the EC brush to the EC wire entering the local connector LOC1. In connector LOC1 since relay 1913 is drawn and relay 1908 has not drawn to indicate that this call cannot be completed, the incoming wire EC is extended to relay 1912. Relay 1912 is therefore blocked by l 'Intermediate earth connected to the inner top contacts of relay 1905 and through the contacts of relay 1913.

   By attracting, the relay 1912 closes a conversation circuit through the negative and positive brushes 1911 of the called line and the capacitors 1928 and 1929 which stop the flow of direct current and therefore prevent the attraction of the relay 1903. The relay 1912 also establishes the connection between the 1942 Tone Common Wire and the Upper Conversation Wire which causes a weak but distinctive tone to overlap in the connection

  <Desc / Clms Page number 95>

 set to play the role of a warning tone for the two subscribers who are in conversation so that the secrecy of this one cannot be violated.



  The operator speaks with the subscriber of set A and informs him of the urgency of the call intended for him. The subscriber can either accept the call that arrives or declare to the operator that he does not wish to receive it.



   If the called subscriber does not wish to receive the call intended for him, the attendant releases the connection by activating the release key K9 by which it bypasses relay 708 and allows the release of the selector switches and the connector. that were used. The attendant can then return the offer key to the normal position and inform the calling subscriber that the offered call has been refused.



   If we now assume that the called subscriber of set A1 of FIG. 16 accepts the new call, the attendant need only return her conversation key K2 and the offer key K6 of figs to their normal position. 11 and 27 to again complete the oonversation circuit through the connection circuits of figs. 10 and 11 and to release the equipment from its position, The connection is therefore established with the busy line of set A1, so the subscriber of set A2 can converse with the calling subscriber of set A1 while the The subscriber with whom the set A1 was in conversation previously remains a third party in the communication. This state of affairs is signaled on the circuit by a warning tone given by wire 1942, as previously explained.

   If the previous conversation has not been terminated and the new communication which has just been established does not require too long a time, the previous connection may remain established if the two subscribers see no objection to this. let their conversation be heard by

  <Desc / Clms Page number 96>

 the subscriber with whom the called party corresponded previously.



   If the new conversation is terminated, the calling subscriber of the set Al hangs up his receiver and therefore cuts the connection established between his line and the line of the called set. The connector in fig. 23 returns to the normal position when the LC1 line circuit is released, which makes it possible to resume the conversation which was in progress previously.



   If it is assumed that the subscribers decide that the previously established communication must be cut off to allow a confidential conversation between them, the called subscriber of the set A1 in FIG. 16 hangs up his receiver and therefore releases his line. The result is that the relay 1913 releases, since its blocking circuit had been transferred to the brush 0 of the connector after the attraction of the relay 1912. The release of the relay 1913 is delayed somewhat because a shunt is placed on its Lower winding. This gives sufficient time to release the plunger from the LS2 preselector of fig. 16 before relay 1913 can release due to the release of the guard earth placed on wire C of the called line.



   When relay 1913 releases, it opens at an additional point the existing local guard circuit, it opens the circuit of relay 1912 which releases and opens the conversation circuit which had been temporarily established, as well as the dial tone circuit. 'warning, finally it establishes the normal test circuit of relay 1917 through brush C. Relay 1917 draws in the circuit of wire C of station Al, through winding 1232 of the called line, and closes the attraction circuit of relay 1918. Relay 1918 therefore establishes the connection to the called line and sends the inrush current to it this

  <Desc / Clms Page number 97>

 in the usual way.

   The subscriber of the station A1 picks up his receiver as for an ordinary call and therefore the various relays of the connector LOC1 operate as stated previously and the conversation can begin.



   Provision has been made in the line circuit LC1 for the means which allow the subscriber who called the operator and who has obtained a communication by means of a switching table connection circuit, to call the operator back to a at any time if he wishes to do so. This arrangement is useful, for example, in the event that the established communication is not the one desired or when it is cut off before the conversation is terminated. In all cases the calling subscriber can manipulate his call dial and emit any number which causes the vibration of the armature of relay 304 which closes the circuit of the lower winding of relay 307 through contacts. relay 306. Relay 307 draws and closes its blocking circuit through the EC wires and contacts of relay 306.

   This blocking circuit comprises the upper contacts of the end supervision relay 706 and the contacts of the conversation key. Lamp 741 lights up in this circuit to attract the attention of the operator.



  This turns off the lamp and releases the recall relay 307 when it activates its reversing key.



  When the communication which has been established through the connection circuit of the passage table and the line of the set A1 in fig. 16 is terminated, the subscribers hang up their receiver. If the called subscriber is the first to hang up, the reversal of the direction of the current, which returns to normal, in the incoming wires of the connector (fig. 23) causes the release of relay 704 which releases the circuit. connection of the operator in about 2 seconds, as described above.

  <Desc / Clms Page number 98>

 



   When the calling subscriber hangs up his receiver, relay 304 of the LC1 line circuit releases allowing relays 305 and 306 to release successively. The blocking circuit which passes through the lower winding of relay 308 opens when relay 305 releases but relay 308 remains blocked at. through wire C until the finderscope returns to the normal position.



  It may be noted incidentally that relay 307 momentarily pulls and locks momentarily in the EC wire circuit, but this circuit is opened by relay 306 and relay 307 releases after supervisory lamp 741 only momentarily illuminates. Relay 305 opens the bridge placed on the negative and positive wires associated with the right windings of the translator coil 530 to allow the connector to be returned to its normal position.



  The relay 305 also connects these wires to the 2 poles of the battery supplying the office for a sufficient time to bring about the release of the relay 305. This operation is of no use in the case of a local call.



   Following the opening of the bridge placed on the conversation wires in the line circuit LC1 of fig.1, the relay 1902 of the local connector releases to allow the release of the latter. The SES secondary selector in fig. 22 and the primary selector in fig. 12 are kept in service for the moment, by means of an earth placed on wire C at the contacts of relay 708.

   In the event that the called subscriber has hung up his receiver and has therefore released the supervision relay 704 and initiate the release of the connection circuit, the relay 704 releases because it is set so that it cannot remain attracted when it is powered only by its bias winding whose effect is relatively weak. when the connection circuit is released, and when the relay 708 releases and clears / earth

  <Desc / Clms Page number 99>

 of wire C of the associated selector, the FS and SES selectors of figs. 12 and 22 return to rest.



   Relay 308 of the LC1 connection circuit releases when the finder is released. It applies again to the incoming wire C a polarity indicating that this device is free to make it available for any call that might arise.



   Prohibition of obtaining calls from the public network.



   It should be especially noted that the attendant of the annex office cannot establish a connection between a trunk circuit coming from the public network (the incoming trunk circuit IC in fig. 7 for example) and a trunk line, such as that shown in fig. 8, nor with a junction line to another annex office, such as that of fig, 9, because the researcher's discrimination brush D finds an earth when one responds to l 'call coming from the public network which attracts the relay 801 as it was said above.



  With relay 801 engaged, when the brushes of the selector FSl are brought to opposite the 9th level (in the event of a call to the group 99 connector) and when the contacts 815 of the 9th level are closed, the 807 relay test circuit is open. Under these conditions, relay 807 cannot attract and the selector continues to rotate until it comes outside the contact bank where it closes the excess contacts 811 and 812. Closing of the contacts d The purpose of excess 811 is to send a busy tone back to the line while closing the excess contacts 812 results in drawing relay 805 again, to open the rotation electromagnet circuit. .

  <Desc / Clms Page number 100>

 



   Outgoing long distance call.



   The way in which calls using trunk lines are handled, such as that associated with the LC3 line circuit of Figs. 2 and 8, will be described below. We will first explain how the connection is established between a local line and an interurban line (an interurban line of group 9941 for example).



   To take a long distance call, the subscriber of the annex office picks up his receiver and transmits the operator's number, ie 97, the result is that a connection is established to this operator in the manner which has been described previously.



   The attendant transmits the desired number 9941 by manipulating her digit key DK in fig. 29 and starts the transmitter by activating the start key which causes the retransmission of digits 9,9, 4 and 1 which had been registered.



   The selector in fig. 12 works when the first digit (9) is emitted and raises its brushes to opposite the 9th level. It then returns to its normal position and operates under the action of the 2nd digit (9), i.e. it raises its brushes to the 9th level and turns them to find a free interurban connector.

   When the brushes of the primary selector FS1 are in front of the 9th level, the shaft contacts 813 of the 9th level are closed, they apply a ground to the TS wire which attracts the relay 707, the relay 707 in addition to what 'it prepares the cutting of the wire EC, at its upper contacts, establishes at its upper internal contacts an additional earth connection of wire 717, it cuts the circuit of the time switch TS at its lower internal contacts and he prepares for his lower contacts a special circuit of liberation.

  <Desc / Clms Page number 101>

 



   If it is assumed that the TC connector in fig. 19 is the first of the long distance connectors which has been found free when the selector FS1 turns to the 9th level, this connector is grasped at terminals 1500 by the brushes 800 of the primary selector FS1, the connector interurban being marked as free by a negative connected to incoming wire 0 and brought through the top winding of relay 1503, engagement contacts 1515 and key 1516. Relay 1503 pulls when connector is on. in service, it prepares the circuit of the ascent electromagnet 1511 and its blocking circuit.



   The commissioning of the TC connector also causes the pulling of the relay 1501 in the circuit of the incoming conversation wires and also pulls the relay 1502 to prepare the operation of the connector under the action of the last two digits (4 and 1 ) of the requested number.



   When the number (4) is received, the 4 pulses generated by the relay 1501 are transmitted through the contacts of the attracted relays 1502 and 1503 to the ascending electromagnet 1511.



   At the end of the upward movement, the relay 1503 releases and transfers the control circuit to the rotation electromagnet 1502, the engagement springs 1515 having been opened.



   When the last digit (1) is received, the rotation electromagnet 1512 operates to engage the brushes 1515 on the first group of 4th level contacts which are assumed to be where the leads 1501 of the junction circuit terminate. go to the LC3 line circuit in fig. 8. Relay 1506 attracts in the circuit of the rotating electromagnet and causes the attraction of relay 1507. This phase of operation is similar to that which has been described above.

  <Desc / Clms Page number 102>

 for relays 1406 and 1407 of connector BC in fig. 18.

   It is interesting to note that a control relay 1508 has been provided, it is connected in circuit with the brush S for the same reason as that given for the corresponding relay 1408 and the brush S of the connector BC, it has intended to give an automatic selection of trunk lines in a group. If we now assume that the first trunk line of the group is free, no earth is found on wire C of group 1551. Under these conditions, since the earth is not given to brush C of the TC connector, the relay 1505 does not attract.

   The successive release of relays 1506 and 1507 results in closing a test circuit, of the type previously described for relay 1509, through brush C of the connector and wire C of group 1551 to the negative wire. battery and via relay 503 which is connected to wire C through contacts of relays 502 and 506. Relay 1509 closes the circuit of relay 1510, thus relay 1510 attracts and establishes the connection to the line long distance. It should be noted that each of the incoming wires of the TC connector is now metallically connected to the corresponding wire of group 1551 and that the line relay 1501 releases because it is disconnected from the conversation wires to the contacts of relay 1510.

   Relay 1502 therefore releases but the connection is kept established because wire C remains connected: to earth while the transmission circuit of fig. 29 and then to the contacts of relay 708 of fig.ll.



  The circuit of the release solenoid 1513 remains open at the lower contacts of the relay 1510.



   In the LC3 line circuit of fig. 8, the relay 505 attracts in the circuit of the wire C coming from fig. 19 and attracts the relay 504 to prepare the attraction of the relay 505 and the relays associated with it.

  <Desc / Clms Page number 103>

 



  While the digit is being sent, the attendant can actuate the response cut-off key K3 which attracts relay 2115 which disconnects the "response" side of the connection, With relay 2115 being drawn, the operation of relay 2103, such as that has been described, cannot be done after the attraction of the relay 2111 when the relay 708 attracts.



   When the attendant is warned by the extinction of the transmission pilot light (2211 or 2142t) that the connection has been established to the interurban line of the desired group, she activates her call key K10 to send the inrush current, on the connection established, via the contacts of relay 2111, the latter having drawn under the action of the key K10. The inrush current passes through the selector of fig, 12 and the working connector of fig. 19 and ends at the trunk line of fig. 8 via the translator coil 530 and the normally closed contacts of relay 505.



   When the inrush current is transmitted, the relay 501 of the line circuit LC3 attracts and closes the circuit of the lower winding of the relay 502 through the EC wire, the relay 502 attracts and locks on this wire, the latter is therefore extended through the connection which has just been established to the answer wire 731 and to the call wire 732 of the position equipment of fig. 26.



   Wires 731 and 732 are connected to negative via a resistor, relays 2115 and 2116 being pulled. In this way the beats of relay 502 of the line circuit cannot be heard.



  Relay 506 releases as soon as the negative is removed from the wires referred to above, when the operator's keys are returned to the normal position.



   When the operator of the remote office answers, she can converse with the operator of the home office

  <Desc / Clms Page number 104>

 and establish the requested communication in the usual way
When she has transmitted the requested number to the operator of the remote office, the operator of the annex office can return her keys to the normal position and allow the operator of the remote office to establish the connection in question.



   Monitoring a communication.



   In the event that the operator wishes to monitor the long distance connection which has just been established, she activates the monitoring key K1 thereby connecting the conversation head and neck wires to the monitoring head and neck wires 729 and 728, grounding the switch wire 730. The earth placed on the switch wire 730 attracts the relay 2102 to connect the operator's receiver to the terminals of the secondary windings of the RC translator coil while it is normally connected to the secondary windings of the induction coil, giving the usual monitoring connection.

   Relay 2102 starts the operation of relay 2103 to apply an intermittent ground to the warning tone circuit which includes the 3rd winding of the induction coil and the 2nd winding of the RC translator coil. At this moment resistor 2162 is incorporated in the circuit, in series with limiting resistor 2161, to adapt the value of the current to the conditions at the time.



  As stated previously, the warning tone produced is sufficient to be heard during the conversation, but it does not disturb the conversation and the operator is able to see if the subscribers can converse properly. At the same time the subscribers can hear the warning signal which informs them that the operator has connected in third party in their

  <Desc / Clms Page number 105>

 conversation.



   Relay 2102 releases when the watchdog key is returned to the idle position and tone generator operation ceases.



   In the event that the trunk attendant rings on the trunk line in fig. 8 either to call back or to give the end signal, relay 501 attracts and closes the circuit of relay 502, which passes through the lower winding of this relay, through the contacts of the attracted relay 503 and the EC wire of the connection established through the switches in service of figs.



  19 and 12, through the contacts of the attracted relay 707 and the contacts of the conversation key K2 and leads to the negative of the battery via the supervision lamp 741. The lamp 741 lights up in the circuit of blocking of relay 602 and gives a supervision signal. The attendant of the annex office answers the call given by lamp 741 by activating her conversation key K2; she therefore connects to telephone communication with the trunk line and cuts the circuit of supervision lamp 741. The lamp 741 therefore goes out and the relay 502 releases.

   After responding to a request from the long distance operator, the attendant in the adjoining office can return her K2 conversation key to the normal position and allow the conversation to continue until the call is terminated,
The local subscriber can also call back the operator of the annex office, to do this he sends the number 1, for example, which causes the momentary release of the relay 304 of the line circuit LC1 and causes the relay 307 to attract. The relay 307 is blocked by the EC wire and through the supervision lamp 741. This lamp goes out and the relay 307 is unlocked and released when the attendant answers.

  <Desc / Clms Page number 106>

 



   When the conversation is finished and the local subscriber hangs up his receiver, the relay 304 releases and causes the relay 307 to be attracted as in the previous case, which causes the lighting of the supervision lamp 741. This lamp goes off. rather lights up incidentally at this time since the connection is automatically released in the manner which will be explained below. Due to the release of relay 304, relays 305 and 306 successively release. when relay 305 releases, it applies the negative of the battery through the negative and positive conversation leads which terminate at the finder terminals 300 for an interval sufficient to allow the delayed relay 306 to release.



   A current therefore circulates in the connection established by means of the switches of FIGS. 10, 11, 12 and 19 to the left winding of the transport coil 530 of the line circuit LC3. This current has the same direction as the current which circulates normally before a response to a local call established by means of the connection circuit of figs. 10, 11 and 12. However, the current flowing through the line winding of supervisory relay 704 is much greater than the current flowing normally through this relay when a call is routed by the attendant to the operator. a line of the annex office, due to the relatively low value of the resistances of the line circuit LC1.

   Hence the line winding of relay 704 attracts the relay although the opposite effect is felt by the action of the locally powered bias winding. Therefore when the supervision pulse is terminated, the polarization winding reverses the direction of the magnetization and causes the release of the relay. Relay 705 attracts when relay 704 does, it prepares the circuit of relay 706, this circuit borrows

  <Desc / Clms Page number 107>

 the contacts of the delayed release relay 705, when the 704 relay releases. Relay 706 is blocked in the working position.

   Since relay 707 is drawn (this is a long distance call) relay 706, at its lower contacts, applies a ground through the lower contacts of the attracted relay 707 at the junction point of resistor 716 and the blocking winding of the relay 702. The relay 702 therefore releases in the usual manner. On releasing, relay 702 opens the circuit of relay 708 which releases after removal of ground from wire 707 by relay 702 and finder F1 returns to idle following release of start relay 702.



   In the LC1 line circuit, relays 307 and 308 release following release of the finder.



  The supervision lamp 741 therefore goes out before the operator has had time to respond after the lighting of this lamp.



   Due to the release of relay 708, wire C of the connection established to the trunk line is no longer connected to earth, it enables the switches of figs. 12 and 19 which have been put into service to release and it allows the line circuit LC1 of fig.8 to release. When the primary selector FS1 of fig. 12 returns to the normal position, the relay 707 releases, it therefore resets the connection circuit of figs. 10, 11 and 12 in normal condition.



   In the TC trunk connector of fig. 19 the removal of the earth from wire C, to relay 708 discussed above, results in releasing the switching relay 1510 which was previously blocked on this wire C The relay 1510 in addition to disconnecting the brushes, closes the circuit of the release solenoid 1513 through the engagement contacts 1514. As a result the connector is returned to position A normal tion in the usual way.

  <Desc / Clms Page number 108>

 



   In the LC3 trunk line circuit of fig. 8 removing the earth from wire C results in releasing relay 503. Relay 503 opens the circuit of relay 504 and closes the circuit of relay 505 through contacts. relay 504. Relay 505 therefore attracts for a short time and applies inrush current to the trunk line to operate an end signal at the remote office.



   Temporary automatic guard of the interurban circuit.



   One of the characteristics of the LC3 line circuit is that it is guarded by the trunk connector after the termination current has been sent and for a period sufficient to allow the operator of the long distance office to take note of the termination signal and switch off. the connection.



  The operation is as follows:
When relay 505 attracts, it closes the circuit of relay 506. Relay 506 disconnects the incoming C wire from the connector bank and relay 503 and connects it to ground, which keeps the trunk line from being intruded through. long distance connectors.



  The relay 506 also extends the positive through its lower internal contacts up to the wire 503 associated with the time device comprising the relays 507 to 510. The wire 533 being earthed, a blocking circuit is established for the relay 506. , through contacts of relay 509 and internal contacts of relay 506. Relay 506 remains drawn into this blocking circuit until the operation of the time device is terminated.



   When wire 533 is grounded, relay 507 draws into the circuit which passes through contacts of relay 508. The armature of this relay is provided with a fairly heavy magnetic mass which is attached to the end of the relay. a spring, when it is

  <Desc / Clms Page number 109>

 actuated, a circuit closes through the contacts of this spring to attract the relay 508. The relay 508 attracts and closes its blocking circuit to its upper spring; it disconnects the wire 533 from the winding of the relay 507, therefore the relay 507 is no longer supplied and it releases, the spring vibrates for a period of several seconds. Relay 508 is delayed on release, so it remains attracted as long as the spring of relay 507 vibrates with sufficient amplitude to touch both contacts.



   When relay 508 transfers wire 533 from relay 507, it closes the circuit of relay 510, of the count pair, through contacts of relay 509.



  Relay 510 attracts and closes its blocking circuit in series with the lower winding of relay 509, but this blocking circuit is not currently carrying any current since the initial circuit is still established. when the vibration amplitude of the pendulum of relay 507 decreases, relay 508 releases and opens the initial circuit of attraction of relay 510. At this moment, relay 509 attracts in series with relay 510. Relay 509, to its spring lower, opens at one point the blocking circuit of the relay 506 but the lower spring of the relay 510 has closed another point of the blocking circuit so that the relay 506 remains attracted. Relay 509 also prepares a blocking circuit for its upper winding and a release circuit for relay 510.



   The relay 508 being released, the relay 507 attracts again which attracts the relay 508 again and opens the circuit of the relay 507 which releases and causes the vibration of its weighted spring.



  * With relay 509 attracted, relay 508 connects wire 533, grounded through the upper contacts of relay 509, to the junction point of the coil of relay 510 and the resistor which is

  <Desc / Clms Page number 110>

 associated, it thereby bypasses relay 510 to release it. The relay 509 remains attracted through its upper winding as long as the relay 508 remains attracted.



   When the weighted armature of relay 507 slows down its movement for the second time, relay 508 releases and finally disconnects wire 503 from relay 506 at its lower spring, thereby opening the blocking circuit of relay 506, relay 509 being attracted and relay 510 released. when relay 506 releases, it disconnects the earth from wire 533, which prevents re-pulling of relay 507. Relay 506 also disconnects wire C from earth and reconnects it to relay 503, which causes the tag to be marked. the trunk line as being free in the connector banks after the interval introduced by the two periods of vibration of relay 507 controlled by relays 508 to 510.



   It should be noted that the operation which has been described above does not interfere in any way with the reception of a call on the long distance line and the start of a searcher if the long distance line has been released at the far end and put into service immediately for a call in the opposite direction.



   Third party introduction into a busy trunk circuit.



   The TC trunk connector in fig. 19 is provided with an offer relay 1504 associated with the incoming EC wire which allows the attendant of the annex office, when required, to establish a connection with a junction circuit. busy or with a long distance line. It can ask subscribers in conversation to hang up their receiver and thereby release the junction circuit in an urgent case. The 1504 supply relay attracts,

  <Desc / Clms Page number 111>

 as described for the offer relay 1912, to establish a connection with the busy trunk circuit (the last of the group); to substitute the warning tone lead 1518 for the busy tone lead 1517 and to transfer the 1905 blocking circuit to sweep C.

   As a result, the relay releases and allows normal commissioning of the line when it becomes free.



   Incoming long distance call.



   The way in which long distance calls to the annex office are routed by the operator will be described below.



   Assuming that the trunk line in Fig. 8 is seized at the far end and inrush current is sent over that line to alert the attendant at the side office, relay 501 pulls in and closes the relay circuit. 502. Relay 502 locks up at its lower internal contacts; it closes the circuit of the group call lamp GC3 in position 1 and the circuit of the corresponding lamps in each of the other positions; it grounds the starter wire 511 to cause a searcher to search and to bring the latter to the correct level of the bank contacts; It connects the C wire associated with the connector bank to earth; finally it connects the wire associated with the researcher to the relay 503 thereby marking the line circuit LC3 as being calling in the researchers' benches.



   When a finder arrives at the terminals of the LC3 line circuit, the finder F1 in fig. 10 for example, the relay 503 draws through the wire C coming from the researchers' benches. By attracting, the relay 503 blocks with the wire C of the finder, it unlocks the relay 502 and extends its lower winding to the wire a to give supervision; finally it draws the relay 504, The GC3 lamp, group call, goes out and the starter wire 511 is

  <Desc / Clms Page number 112>

 grounded.



   The attendant of the annex office can route the incoming call to the line of any subscriber in the annex office, to another inter-city line or to any of the outgoing lines to a remote annex office, such as the line of fig. 9. In the event that the connection is extended to one of the local lines of the annex office, this connection is released under the control of the time switch TS when the subscriber of the annex office hangs up his receiver and allows the supervision relay 704 to release; the release operation has been described previously.



  On the other hand, if the connection is extended to another trunk line or to an outgoing line to a remote annex office, relay 704 does not attract to give answer or end supervision and therefore can control the call. release the connection.



  In this case, however, the relay 707 attracts through the contacts 813 (fig.12) to open the circuit for starting the switch to. TS time and therefore prevent any untimely operation of this device. Relay 707 also connects the EC wire of selector FS1 to the EC wire of researcher F1, these two wires being connected through contacts of the conversation key K2 in the normal position (during conversation) to the supervision lamp 741. This lamp therefore lights up under the control of one or the other of the two ends of the link and gives an end or reminder signal.

   For example, if the calling long distance operator rings the end of the ring, the ringing current arriving from the long distance line to the LC3 line circuit in fig. 8 causes the attraction of relay 502 and relay 503 which is blocked by the 'intermediate its lower winding on the associated wire EC in series with the 741 lamp. Relay 502 releases when the attendant activates her key

  <Desc / Clms Page number 113>

 conversation and the connection is released when the attendant activates her release key to release relay 702.



   When the communication is terminated, the end signal by ringing current is given as has already been described and the LC3 line circuit is prevented from being taken by a connector of the annex office until the determined period of time. has elapsed. Guard is given by relay 506 during the interval determined by relays 507 to 510. Guard is caused as previously described by the pull of relay 505, following release of relay 505.



   Call of long distance lines by a subscriber of the annex office.



   It should be noted that the connectors of the annex office, such as the connector of fig. 18, can give communications with the trunk lines in the case where it is desirable to allow the subscribers of the annex office to call the trunk lines direct. - definitely. For example the negative, positive and C wires of group 1501 can be connected to the corresponding contacts of the same bank of the connector of fig. 18. It will be recalled that the connector of fig. 18 emits a ringing train when the relay 1404 attracts when the line is seized. This connector is also provided, as described above, to attract relay 1404 again to call back the operator in the event that the calling subscriber manipulates his call disk for this purpose.

   In addition, the connector of fig. 18 has been specially arranged so as not to send the inrush current unnecessarily when the subscriber called from the annex office hangs up his receiver because trunk circuits such as those shown in LC3 , fig. 8, have the characteristic

  <Desc / Clms Page number 114>

 send an end signal on the junction circuits.



   Delayed calls.



   As stated previously, provision has been made for the operator to be able to set up delayed calls. This facility is particularly useful to allow the attendant of the annex office to establish a connection between a line of the published network and a line of the annex office after the subscriber of the annex office has already tried to establish a connection with. this line but could not do so because the line to the public office is busy. In this case, the calling subscriber from the annex office sends the No.97 assigned to the operator and gets in touch with the latter via a line circuit such as LC1 in figs. 1 and 6 as has already been described above.



  It should be noted in particular that the operator cannot rout the call in the regular manner while the calling subscriber keeps the line because the primary selectors connected to the researchers do not have access to the trunk circuits to the office. publishes, The operator takes note of the subscriber number of the calling annex office and the number requested in the public office. It then establishes from its position a connection to each of these lines.



   As has already been said, the delayed call selectors are designed to be used in common by all the operators of the annex office and they are accessible via the first level of researchers. The DOS selector in figs. 3 and 13 is one of these delayed call selectors.



   In order to prepare the use of a delayed calls selector, the operator in position 1 activates the delayed calls key K7 in fig. 27.When this key is activated, the earth of the contacts of the control key release is applied to the upper winding, from the

  <Desc / Clms Page number 115>

 relay 2114 which attracts this relay in series with the upper winding of relay 2110. Relay 2110 attracts to release relay 2112.

   At its upper contacts, relay 2114 places an earth on the marking wire which is associated with it and which is multiplied in the searchers accessible from position 1 but which does not extend to the searchers associated with the other positions since each position is provided with its own wire for marking delayed calls. As the delayed calls key remains activated, the operator also activates the conversation key of a free connection circuit, the conversation key K2 of FIG. 11 for example. This attracts relay 703 from the connection circuit and relay 2104 from the position equipment.

   Grounding wire 2123 by relay 2104 results in closing a circuit through contacts of the drawn relay 2110 and through wire 2104 to cause the selection of a free transceiver, but the relay 2112 is not attracting at this time because the 2110 relay is itself attracted.



   The delayed call key k7 being actuated and the relay 2114 drawn, the earth is extended by the intermediary of the contacts of this key and the contacts of this relay up to the starter wire 727 and, moreover, it is extended to through contacts from relay 703 to finder relay 702. The seeker therefore goes in search of the calling line but the asoension movement ends after the first step when the ascent test brush 712 meets the first level marking contact which has been grounded, as on said it above. The brushes 700 of the Fl searcher turn in the field of the contacts of the first level in search of a free delayed calls selector.



   If we assume that the DCS free call selector in fig. 13 is the first that is found free, this

  <Desc / Clms Page number 116>

 selector is seized through its incoming threads. The DOS selector is normally marked as free by the negative applied to wire 0 through one of the occupancy keys and the coil of relay 901. Relay 901 draws into the circuit of wire 0 to connect the negative, positive and negative wires. C and to prepare the blocking circuit of relay 902. The group identification lamp 115 of position 1 lights up in the circuit of wire L and brush L of the searcher to inform the attendant that the researcher found a free delayed call selector.



   Delayed Call Selector Relay 903 is bridged to the incoming talk wires, through contacts of relays 908 and 902 when relay 901 attracts, Relay 903 thereby draws into the negative and positive searcher brush circuit Fl, through the contacts of the relays 708 and 703, the positive wires 721 and 723, the contacts of the relay 2115 and the choke coil 2118. following the attraction of the relay 1903, the relays 1904 and 1905 prepare for operation of the selector.

   We have found it interesting to provide the operator with a CD call dial (fig. 27) which allows her to establish connections through the delayed call selectors, which means that the transceivers in the annex office cannot be fitted. that a sufficient number of digit registers (5) to serve the numbers of the annex office, the numbers of the public office in general containing more digits, particularly when the digit "0" must be sent as a prefix for calls to the public office.



   When she notices that the ILS lamp in fig. 13 is on, the attendant can start sending, using her call dial, the number of the line called in the public office. It precedes this number by the digit "0" necessary to give access to the

  <Desc / Clms Page number 117>

 public office. when the call dial returns to the normal position, after the emission of the first digit, the engagement contacts (the lower group) extend an earth to the winding of relay 2115. This relay attracts to bridge the contacts of Pulses from the CD call dial directly to the lead and back answer wires 724 and 722 via the delayed call key contacts K7.

   Therefore when the CD call dial returns to the normal position 10 momentary interruptions are made from the picks in the / line relay of the DOS delayed calls selector in fig.9. when the call dial has returned to the normal position, relay 2115 releases, it transposes the wires 722 and 724 on the alla choke coil and on the wires of the operator's set, which allows the operator to be listening between the various transmissions of the call dial to follow the progress of the communication,
In the DOS delayed calls selector in fig. 13, the 10 interruptions in the circuit cause ten times the momentary release of relay 903,

   which causes the ascension solenoid 909 to operate ten times to bring the brushes 900 in front of the 1 th level of the bench contacts. Relay 906, whose top winding was initially energized through engagement contacts 915 when relay 901 pulled, releases at the end of the upward movement and sets up the rotation electromagnet 910 circuit. The brushes 900 then rotate in the 10th level of the bank contacts until they reach the terminals of a free repeater associated with an outgoing junction circuit such as the OR1 repeater of FIG. 17 associated with the outgoing junction circuit OT1.



  At this moment the relay 908 attracts to put the OR1 repeater into service while the relays 903, 904 and 905 release due to the attraction of the relay 908.

  <Desc / Clms Page number 118>

 



   In the repeater OR1, the relays 1301 and 1302 attract as described previously. The relay 1301 places at its lower contacts a bridge on the wires of the junction circuit exiting through the left windings of the translating coil 1330. As a result of the closing of this bridge, the equipment of the public office is ready to receive the digits of the called subscriber's number and the normal invitation to transmit tone is returned to the line to indicate that transmission can begin.



   In the equipment of the operator position of fig. 21, the relay 2116 releases when the call dial has returned to the idle position, which allows the operator to hear the invitation to transfer tone. put that comes to him from the public office. When she hears this signal, the operator uses her call dial to send the various digits that constitute the requested number, which establishes the connection to the requested subscriber of the public office.



   When she has sent the number, the attendant returns the delayed call key K7 to the normal position, which opens the circuit of relay 2114 and removes the earth of the starter wire 727 and at the same time disconnects the pulse contacts. of the CD call dial. Before the call dial is disconnected, the contacts close. switch off before cutting the deferred call key place a shunt on the pulse wires through contacts of relay 2114 so that a bridge remains placed on the pulse wires until, until relay 2115 releases ( following the return to the normal position of the call dial), they transpose the response head and neck wires 724 and 722 onto spool 2118.

   It should be noted that a blocking circuit is maintained through the winding /

  <Desc / Clms Page number 119>

 of relay 2114 and the contacts of relay 2115 to ensure that relay 2115 will release before relay 2116. Of course, relay 2115 usually releases before the attendant has returned the delayed calls key to the normal position since Only a fraction of a second is required to release relay 2115 when the circuit is open to the CD call dial engagement contacts.



   It should be noted that the relay 2110 does not release when the deferred call circuit is open because this relay is kept drawn into the circuit of the release wire 726 as has already been explained,
It also results from the normal setting of the deferred call key K7 that an earth is extended through the upper contacts of the key and the contacts of relay 2114 to wire 731 for the entire time necessary for releasing relay 2114 after its circuit has been opened by the delayed calls key.

   An impulse is therefore sent on wire 731 through the contacts of the activated conversation key K2, the upper spring and the contact at rest of the end supervision relay 706, the EC brush of the researcher F1, the incoming EC wire of the selector DOS delayed calls in fig. 13 and contacts from relay 1901 to 2-step relay 902.



  Relay 902 pulls at first only to close its blocking contacts when the upper winding alone is energized.



   When the pulse is over, when relay 2114 releases, relay 902 fully draws and extends the incoming wire EC through contacts of relay 908 to the brush EC, so this wire is extended to the circuits of following junction provided that they have an EC wire. The function of relay902

  <Desc / Clms Page number 120>

 is to insert the translator coil 930 into the conversation circuit. When relay 902 is pulled, the incoming wires are extended to the left windings of the translator coil 930 while the right windings of the translator coil 930 are bridged to the outgoing wires, through the negative and positive brushes and relay contacts. 908.



   If we now assume that the called subscriber in the public office answers, the attendant in the annex office informs him that a call is intended for him and asks him to wait a moment while she completes the connection. in the other direction. The operator establishes this connection to the local line by transmitting the digits of the subscriber's number of the annex office by means of the digit keys DK as described above, and by activating the start-up key. This operates the primary selector FS1 in fig. 12 and other suitable switching devices, as previously described, to establish the connection to the local line.

   The operator can activate her K3 cut-off key and get in touch with the local subscriber to inform him that his correspondent in the public office has answered. The operator places the key in the normal position to establish the desired connection.



   It should be noted that the DOS delayed calls selector is provided with a pair of shaft contacts associated with level 0. These contacts are closed for the moment, because the DOS selector has been brought in front of the 10th level in the case of a call to the public network.



  The relay 901 being attracted, the earth is applied through the contacts of the connection relay 901 to the discrimination wire D which extends a ground through the brush D, the searcher Fl and the contacts of the relay 701 up to relay 801 of the primary selector FS1.

  <Desc / Clms Page number 121>

 



  As described previously, this class registration relay being attracted, the call can only be extended through the primary selector FS1 only to the lines which can be put into communication with the office. public.



   Attraction of relay 704: when the local subscriber answers, results in attracting relay 705 to prepare the circuit of relay 706. Therefore, relay 706 attracts when the local subscriber hangs up his receiver, it closes its blocking circuit so that the connection is released after a time of about 2 seconds by the operation of the time switch TS as explained previously.



     The placing of the researcher Fl in the rest position has the effect of opening the circuit of the relay 901 of the delayed call selector DOS. Relay 901 opens the blocking circuit of relay 902, which releases since the outgoing conversation wires are no longer bridged, which allows the line and release relays of the OR1 repeater to release and removes the earth of the associated incoming 0 wire, Delayed call selector relay 908 releases and closes the release solenoid circuit through engage contacts 1916. The selector returns to the normal position in the usual manner.



   It should be noted that the delayed call selector wire C remains connected to earth to the upper internal contacts of relay 901 as long as the latter remains attracted; therefore the established connection is maintained when it includes a circuit such as the trunk line LOS circuit of fig. 8 (reached via a trunk connector) which does not give guard polarity on the wire vs.

  <Desc / Clms Page number 122>

 



   Special precautions.



   Arrangements have been made to short-circuit the distributor of fig. 24, to put out of service one or the other of the two emission circuits of figs. 28 and 29 in the event that one of them becomes defective and to use the CD call dial in fig. 28 instead of the transceiver when it comes to establishing local calls and that the connection circuits of figs. 28 and 29 are also defective.



   If the distributor in fig. 25 is broken, it can be dispensed with by actuating the 2006 key, which attracts the 2005 relay. The 2005 relay being attracted, the associated common starter wire, checked by relay 2001, is connected to each of the 4-position starter wires, such as wire 2033 in position 1, and therefore the starter wire in each position is grounded each time the relay 2001 attracts.

   Under these conditions, a seeker is put into service at each position where the conversation key of a free connection circuit is activated and the first seeker who arrives on the calling line seizes this line and immediately keeps it in the manner which has been previously described, while the finder (or finders) who have not reached the line continue to turn to the limit of movement, at this point the excess contacts are actuated to return the finder to position. normal. At this time the common start wire is no longer connected to ground unless another call has occurred in the meantime.

   In the finder F1 of fig. 10 for example when the vertical brush of wire 712 does not find a marked level wire, the ascent ends at the test contacts of the 10th level which is permanently earthed.



  In this case the brushes rotate in the 10th level.

  <Desc / Clms Page number 123>

 



  When the brushes are rotating and a calling line is not found, the excess contacts 714 separate when the brushes come out of the contact bank. Since the engagement contacts 715 are open, the separation of the contacts 714 opens the circuit of the relay 712 and allows the latter to release the finder. The seeker returns to the normal position and relay 702 cannot attract again until the engagement contacts 715 have closed again. In the event that the shutdown circuit Si.2 becomes defective, the operator, observing the modeling lamp 2142, may notice that the connection circuit is not working correctly.

   In this case, it can actuate the key 2203 to open its lower contacts which prevents the attraction of the relay 2201 to select the transmission circuit SL2. Since there is no longer any blocking circuit for relay 2202, this relay pulls whenever the transmitter start wire 2141 is grounded in the position equipment, causing the relay to trip. continuous service of the transmission circuit SL1 instead of making it work alternately with the transmission circuit SL2.

   Under these conditions, during a period of heavy traffic, the operator must not activate the conversation key of a free connection circuit in order to accept a new call until the pilot light 2111 which burns. weakly has extinguished after releasing relay 2207 to indicate that the number which has been registered has been retransmitted completely and that the transmission circuit has become free again.



   In the event that it is the transmission circuit SL1 which has become defective, instead of the transmission circuit SL2, the operator can actuate the key 2203 in the opposite direction to close the upper oontacts of this key. Under these conditions, relay 2201 attracts,

  <Desc / Clms Page number 124>

 whenever the 2141 start wire is grounded while the 2202 relay is shunted by the applied earth through the 2141 start wire through contacts of the drawn relay 2201 at the junction point of the 2202 relay and the resistance associated with it. With relay 2201 pulling alone each time the start wire 2141 is grounded, send circuit SL2 is turned on for each call instead of being turned on alternately with send circuit SL1.



   In the event that the two transmission circuits become defective, the attendant no longer uses the DK digit keys but uses the K8 emergency key.



  When the key K8 is activated, the circuit of relay 2116 is closed and the call dial CD is connected, through contacts of relay 2116 to the head and neck wires, call, 723 and 721. The K8 emergency key also applies a positive to wire 735 through its upper contacts and through the upper winding of relay 2117. Relay 2117 draws into this circuit and locks up through contacts of the relay. relay 2116. In the connection circuit which is shown, the wire 735 is extended through contacts of the conversion key K2 to the relay 708 which causes this relay to attract when the emergency key is activated. Relay 708 closes its upper contacts and thereby extends the transmission circuit to the primary selector FS1.



   The CD call dial can be pressed several times consecutively to transmit the successive digits of the requested number.



   When the K8 emergency key is put in the normal position, the CD call dial is disconnected but a temporary guard bridge is closed on the transmission wires through the closing contacts before the disc key is broken and lower contacts of relay 2117

  <Desc / Clms Page number 125>

 to maintain the connection until relay 2116 has released to replace bridge 2118 on wires 721 and 723. Relay 2116 allows relay 2117 to release.



   Outgoing calls from office 9 to office 8.



   How outgoing calls from office 9 to office 8 are routed will be explained below. It has been explained previously, in relation to figs, 1, 2, 3 and 4, that the calls coming from the office 9 directly or in transit and intended for a subscriber of the office 8 or to his satellite 86 are routed through the intermediary of the 8th level of the primary selectors such as the primary selectors FS1 to FS5 in fig.3 up to desk 8 through the junction circuits operated in one direction such as T3 and to. through trunk circuits operated in both directions such as T2, when trunk circuits operated in one direction are all in service.

   The repeaters R2 and R1 of figs. 20 and 21 are accessible via terminals such as 1600 and 1700 to office primary selectors 8. Each of these repeaters is provided with terminals associated with wires 1613 to 1615 of the interchange circuits between offices for the repeater. Ra and wires 1713 to 1715 for the repeater Rl, The repeater R2 which is associated with one of the outgoing junction circuits operated in only one direction has the wires of this junction circuit (T3) connected directly to terminals 1613 and 1614 and terminal 1615 is not used, In repeater R1, the associated junction circuit Ta being a junction circuit operated in both directions, the transfer relay 1711 is connected to terminal 1715,

   while the associated junction circuit T2 is connected to the contacts of relay 1711 as shown. He/

  <Desc / Clms Page number 126>

 
It should be noted that the EC wire entering the repeater R1 and coming from the terminals 1700 is extended, through the normally closed contacts of the relay 1703, to the upper right terminal of the transfer coil. This connection is established for the purpose of extending the registration pulses of the class and sending the call to trunk circuit T2.



   When the repeater R1 is entered at terminals such as terminals 1700, after the number 8 has been issued, the relay 1701 draws through the left windings of the translating coil via contacts of the relay 1706. The relay 1701 is activated. attract relay 1702 and this applies a ground to the incoming wire C to keep the connection established.

   Relay 1702 also prepares the circuit of relay 1703 and completes a loop through the straight windings of the transfer coil and the contacts of relay 1701, using terminals 1713 and 1714, this loop includes relay 1704 and l The upper winding of the relay 1705. The relay 1702 also closes the circuit of the bias winding 1705 and the circuit of the lower winding of the relay 1709.

   Relay 1709 pulls in and places extra guard polarity on wire C to. through contacts of relay 1710; it prepares the insertion of the high resistance relay 1710 in the conversation wires when the relay 1702 releases; it prepares the blocking circuit of relay 1708; finally at its lower contacts it closes the circuit of relay 1711. The relay 1711 attracts to disconnect the negative and positive wires, from the junction circuit between offices, from the arrival selector IS2 in fig.14 and to connect them to terminals 1713 and 1711 of the repeater Rl. The operations which are described above are carried out quickly.

   Therefore, the connection through the repeater to the connecting wire. T2

  <Desc / Clms Page number 127>

 closes before the end of sending the class registration pulse on the incoming wire EC, in the event that a class registration pulse is to be received. The junction circuit operated in both directions T2 is extended via the contacts of transfer relay 2711 associated with repeater R4 of office 8 to the arrival selector IS4 of this office (figs. 34 and 33). Line relay 2602 of the IS4 inbound selector is normally placed on the T2 junction circuit wires in series with the office call dial.

   Therefore the closing of the bridge on the wires of the junction circuit T8, when the transfer relay 1711 of the repeater R1 attracts, has the result of attracting the relay 2602 to prepare the operation of the selector by attracting the relays 2603 and 2604 .



  Applying a ground to the C wire of the selector also grounds the C wire of the R4 repeater to mark the junction circuit, operated in both directions, as busy in office 8.



   The relay 2601 is connected in series with the conversation wires entering the selector R4 and therefore in the case of a call coming from the public office when a registration pulse of the class is received on the EC wire entering the the repeater R1 when it is seized, the momentary grounding of the junction circuit T2 has the result of unbalancing the relay 2601. This relay therefore attracts and closes the circuit of the relay 2607 through the contacts of the relay 2606.



   Relay 2607 thereby attracts and locks at wire C; it opens its initial attraction circuit and at its upper contacts it prepares the return of a registration pulse from the class to the switch or junction circuit which the arrival selector will enter.

  <Desc / Clms Page number 128>

 



   In the repeater R1 of fig. 21 each time a digit is received, the relay 1701 attracts and repeats * at its upper contacts, the pulses to the distant office. Relay 1703 draws across the lower contacts of relays 1701 and 1702 during each series of pulses.

   At its lower contacts, the relay 1705 short-circuits the left winding of the translator coil to reduce the impedance of the line relay circuit 1701 during transmission, while at its upper contacts it disconnects the wire. input EC and switches off the lower right winding of the translatrioe coil as well as the guard bridge through relays 1704 and 1705, thereby giving the upper contacts of relay 1701 more direct control of the pulses sent to the relay. outgoing loop.



   At the end of the pulse train, relay 1703 returns the guard bridges to the conditions existing previously and again connects the incoming wire EC to the outgoing negative wire.



   In the incoming selector IS4, relay 2602 responds to the first group of repeated pulses and actuates the ascender electromagnet 2608 to bring the brushes 2600 in front of the desired level of bank contacts.



  The relay 2705 which initially attracted under the action of the relay 2604 through the engagement contacts 2613 releases at the end of the upward movement and closes the circuit of the rotating electromagnet 2609 through the contacts. 2612. The rotational movement therefore begins and continues until the relay 2606 is operated in the brush circuit C of a free junction circuit to transfer the connection to this free junction circuit. If the relay 2607 has attracted, as described previously, a class registration pulse is transmitted, through the brush EC, after

  <Desc / Clms Page number 129>

 operation of relay 2606 and until relay 8604: has released.



   If the 2nd digit of the number is one of digits 2 to 4, a local connector such as the LOC3 connector in fig. 4 is put into service. This local connector is identical to the local connector LOC1 in fig. 23 described previously. This connector therefore works under the action of the last 2 digits of the number and establishes or not the connection to the called line according to the class of the called line and according to the class of the calling line as determined by the state in which is relay 1908 of connector LOC1 and the state of relay 1907 of connector LOC1.



   If the called line is busy and the call has been established through the pass table and when the operator has received instructions to offer the call to the called line, receipt of the call The supply pulse on the incoming wire EC of the repeater Rl of fig. 24 results in transmitting a pulse through the contacts of the relays 1903 and 1702 and through the negative wire of the junction circuit T2 which unbalances momentarily the relay 1601 circuit. This relay attracts and repeats the pulse through the EC brush of the incoming selector IS4, which attracts the relay of the connector of the office 8 corresponding to the relay 1912 of fig.23.



   When the called subscriber answers and thus causes the usual reversal of the direction of the current, the relay 1705 of the repeater R1 attracts and makes the relay 1706 attract to reverse the connection between the incoming conversation wires of the repeater and the windings of the relay 1701 to give a response supervision at the calling office.



   Relay 1706 attracts relay 1707 to prepare for more efficient pulse repetition

  <Desc / Clms Page number 130>

 callback in the event that the call must be extended through the passage table and the called subscriber wishes to call back the attendant of the annex office by manipulating his call dial. In this case, the operation of the called subscriber's call dial causes the release of the connector's supply relay and causes it to attract again one or more times to cause one or more momentary reversals of the direction of the current. conversation threads. Relay 1705 momentarily releases each time the current direction is momentarily returned to the normal direction.

   Each time he releases relay 1705 opens the circuit of relay 1708 to restore the current direction to normal momentarily in the conversation wires entering the repeater. Relay 1705 also closes the circuit of relay 1703 through contacts of relay 1707; therefore, the relay 1703 attracts during the sending of the train of the return pulses to bypass the left lower winding of the translator coil and reduce the impedance of the latter. Relay 1703 does not bypass relay 1705 at this time as it does when the digits of the called number are sent to the remote office, because relay 1705 does not have to stay on to repeat the callback pulses.

   Due to the change in the upper spring circuit of relay 1707 the upper spring of relay 1703 now places resistor 1712 in parallel with the coil of relay 1704 to reduce the circuit impedance.



   At the end of the sending of the recall digit, the relay 1705 remains in the attracted position as well as the relay 1706 and the relay 1707. The relay 1703 then releases.



   If the called subscriber is the first to hang up his receiver at the end of the conversation, the relay 1705 releases followed by the release.

  <Desc / Clms Page number 131>

 successive relays 1706 and 1707. Relay 1703 draws for the time interval required by relay 1707 to release, whereupon relay 1703 also releases. The repeater remains in this state (with relays 1701, 1702, 1704, 1709 and 1711 drawn) until the calling subscriber has hung up his receiver.



   When the receiver is hung up on the calling station, the relay 1701 releases and opens the outgoing loop, at the same time the relay 1703 attracts again incidentally. Relay 1702 releases after a while and opens the circuit of relay 1703 to allow it to release. The relay 1702 also removes the earth at one point of the incoming c wire, but the C wire remains connected to earth for the moment when contacting the 1709 relay.



  Relay 1702 also opens the initial attraction circuit of relay 1709 but this relay remains blocked for the moment through the upper inner contacts of relay 1710 and earth taken through the upper contacts of key 1716. The relay 1702 also places the high resistance relay 1710 on the outgoing wires through the contacts of relay 1709. Relay 1710 therefore tests the wires to determine if there is no polarity applied to them at the remote office, as normally occurs when a communication is blocked by a malicious call as will be explained below.



  Under normal conditions the relay 1710 therefore draws in series with the line relay of the remote office but a line relay set normally cannot attract when it is in series with the relay 1710 due to the high resistance of the latter. . Relay 1710 cuts the ground of wire 0 at its top contacts and opens the blocking circuit of relay 1709 at its inner top contacts. Relay 1709 therefore releases and opens its blocking circuit at an additional point, as well as a

  <Desc / Clms Page number 132>

 point in the circuit through which earth was previously applied to the wire c. At its upper contacts, relay 1709 disconnects relay 1710 from the bridge placed on the conversation wires and therefore relay 1710 releases.

   Finally the relay 1711 releases following the release of the relay 1709 and retransfers the wires of the junction circuit T2 to the incoming selector of fig.14.



   From the description of the operation of the repeater R1 which has just been given, it can be seen that in addition to the repetition of the pulses in the normal direction and of the supervision and recall pulses in the opposite direction, it also repeats the pulses received on the EC wire as if the line wire was unbalanced; therefore, relay 2601 of the incoming selector IS4 can relay this imbalance back onto the line as a ground pulse on the EC wire of the remote office.



  As a result of this arrangement, the application of an earth to the incoming EC wire of the repeater R1 of fig. 21 results in the application of an earth to the EC wire of the incoming selector IS4 under the control of relay 2601. of the repeater in the event of a malicious call will be described later.



   Local calls in the office 8.



   Referring to fig. 39, we will now explain how the local communications are established in office 8.



   Calls from the full service line of station A3 (N 8225) flow through the preselector LS7 identical to the preselector in fig.16, and primary selectors such as the primary selector FS6; this selector is identical to the FS5 selector in fig.16 except that it falls back to the normal position of the 5th level instead of the 9th level, the first digit of all office numbers 8 being the number 8. The primary selector FS6 has access to local connectors, such as connector

  <Desc / Clms Page number 133>

 local LOC3, just like the incoming selectors, such as the one shown in figs. 32, 33, 38 and 39, while the local connectors have access to all the local lines.

   The preselector LS8 is associated with the local connector LOC3 for the information service as it has been described for the local connector of fig. 23 while the preselector LS6 is represented as being associated with the outgoing repeater OR2 to provide the dtinfor service. in the event of outgoing calls from office 8 to the public office. The outgoing repeater OR2 is identical to the outgoing repeater shown in fig. 17.



   Outgoing calls from office 8 to office 9. when a subscriber of office 8 wishes to get in touch with a subscriber of office 9 or a subscriber who can be reached through office 9 or if he wishes to call the attendant of the annex office (No.97) emits the number 9 as the first digit of the number which causes the primary selector (the primary selector FS6 in fig. 35) to take a junction circuit on the 9th level. calf, such as the junction circuit Tl associated with the repeater R3 in fig. 31 or a junction circuit T2 operated in both directions, associated with the repeater R4 in fig. 34 in the case where all the circuits of junction operated in one direction are already in service, repeaters R3 and R4 of figs.

   31 and 34 are all similar to the repeater Rl of fig. 21 except that the repeater R3 is not provided with a transfer relay while the repeater R4 is provided with the transfer relay 2711 corresponding to the transfer relay 1711 of the repeater. Rl.



   If we now assume that the repeater R4 is put into service from office 8, at terminals 2700, relay 2711 attracts as explained in the case

  <Desc / Clms Page number 134>

 of relay 1711 and bridges the conductors of the junction circuit T2 on terminals 2713 and 2714.



   In office 9, the T2 junction circuit is normally connected through contacts of relay 1711 (fig.2l) to the incoming wire of the input selector IS2 in fig.14. Therefore, when the T2 junction circuit is put into service at office 8, the relay 1001 of the arrival selector attracts into the loop of the T2 junction circuit and causes the attraction of the relay 1002; the relay 1002 prepares the circuit of the ascending electromagnet 1005 and causes the relay 1003 to be drawn through the engagement contacts 1009. when the relay 1002 earths the wire C an earth is extended until to wire C entering from repeater R1 in fig. 21 to which conductor C entering from selector in fig. 14 is connected, repeater R1 is therefore guarded against being put into service at the office 9.



   The selector in fig. 14 operates under the action of the next digit of the called number as explained for the selectors which have been described previously except that the arrival selector IS2 is, in principle, a selector of the simplest form, while the selectors which have been described previously each had one or more additional relays.



  Suffice it to say that the brushes 1000 are brought in front of the desired level of bank contacts and then automatically rotate in search of a free junction circuit after which normal switching operations take place.



   Outgoing calls from office 8 to satellite office 86.



   How calls originating in or passing through office 8 and destined for satellite 86 are routed will be explained below.

  <Desc / Clms Page number 135>

 



  Referring to fig. 4, it will be noted that the 6th level of the arrival selectors IS3 and IS4 and the local primary selector FS6 of the office 8 give access via repeaters, such as R5 and R6, to junction circuits, such as T5 and T6, leading to the satellite office 86 in fig.5. The T6 one-way junction circuit ends at the ICI incoming connector of satellite office 86 while the T5 two-way junction selector (there are three such junction circuits) ends. to the inlet connector IC2 and is also accessible from the SR repeater selector.

   We can therefore see that when the 2nd digit is 6 if the first digit is 8 (the primary circuit FS6 returns to the normal position when the digit 8 is sent as the first digit) a junction circuit leaving to the office 86 is seized, from this makes an inbound connector at the satellite office 86 is put into use to establish communication to the requested line of the satellite office.



  The repeaters R5 and R6 associated with the junction circuits T5 and T6 are shown in figs. 40 and 41 while the incoming connectors ICI and IC2 are shown in figs. 44, 45 and 42, 43. For the purpose of explaining the operation, it will be assumed that the office 86 is called while the junction circuit T6 of FIG. 41 operated in one direction is already in service. It will be assumed that the jonotion circuit T5 operated in both directions is free and that the repeater R5 is entered at terminals such as 3300 by one of the selectors having access to it in office 8, As the repeater R5 is identical to the repeater shown in fig. 21 the transfer relay 3311 attracts to transfer the wires of the junction circuit T5 of the incoming repeater IS6 to terminals 3313 and 3314.



   In the inlet connector IC2, figs. 42 and 43, relay 3503 is placed on the incoming wires through contacts of supervision relay 3508 and in

  <Desc / Clms Page number 136>

 series with the relay 3507. The relay 3503 therefore attracts when the junction circuit T5 is seized in the office 8 and it prepares the operation of the selector by causing the attraction of the relays 3504 and 3505; relay 5506 attracts through engagement contacts 3508. Additionally if a class save pulse is received at the time of commissioning, relay 3507 draws to close the circuit of relay 3520, through contacts 3530, and relay 3520 closes its blocking circuit at its lower contacts and through the lower contacts of relay 3505.



   It may be interesting, in this case, to point out that the incoming connector I02, as well as the incoming connector HERE, is identical to the local connector LOC1 in fig. 24 (the operation of this one has already been described) except that it has in addition the relays 3501 and 3502 which are used in the case of the putting into service of the junction circuit T5, operated in both directions, and that 'it has a relay 3507 corresponding to relay 2601 of the arrival selector IS4 in fig. 33. For this reason, the operation of the incoming connector IC2 will be described more or less briefly and with reference to the description which was given previously of the operation of the connector shown in FIG. 19.



   When the tens digit of the called number is issued, line relay 3503 follows the pulses and operates the ascending solenoid 3524 which raises brushes 3500 to the desired bank contact level. At the end of the ascent movement, relay 3506 releases and transfers the control circuit to the rotation electro 3525.



   When the last digit is output, the 3521 rotation electromagnet follows the pulses and rotates the 3501 brushes until they reach the terminals of

  <Desc / Clms Page number 137>

 the called line, the A4 extension line (No. 8665 for example).



  The 3519 and 3518 relays attract during the rotational movement and they work together with the 3517 relay to allow the line to be tested through the connector's C base and line C wire to determine if the line is ci is free or occupied. Assuming the line is free, test relay 3522 draws into the circuit of wire C and in series with the cutoff winding (not shown) of the pre-selector LS10 associated with the called line.



   Relay 3515 pulls when releasing relay 3519 in the event that relay 3520 has already drawn and in the additional case where the called line is a restricted service line, which is not currently the case.



   In the example in question, the pull of relay 3522 is followed by the pull of relay 3523 which grasps the line and applies the inrush current to it in the usual manner. when the called subscriber answers, relay 3513 attracts and closes its blocking circuit. In addition it closes the conversation circuit and places the guard of the called line under the control of relay 3515, this relay attracts as a result of the attraction of relay 3509 in the circuit of the called line, it closes at its upper internal contacts Relay 3505 blocking circuit after relay 3503 has drawn.



   Relay 3509 also attracts relay 3508 to provide directional reversal supervision in the incoming wires of the connector and hence in the T5 junction circuit. In the event that the call comes from the public network, the subscriber of the called station A4 in fig. 14 can send an information call by pushing the earthing button associated with his line. does he attracts relays 3512, 3511 and 3510 which provide this service as it has been described for.

  <Desc / Clms Page number 138>

 local connector lOC1 of fig.23 where the correspon- ding relays carried Nos. 1926, 1910 and 1905.

   Assuming that the called subscriber is the first to hang up his receiver at the end of the conversation, relay 3509 releases and allows relay 3508 to release and give end supervision. Relay 3509 opens the circuit of relay 3515 which releases and opens the circuit of relay 3505.



  Relay 3505 on releasing disconnects ground from desktop C to its upper contacts, while at. its lower contacts it opens the blocking circuit of relay 3523 and allows the latter to release by releasing the called line.



   When the receiver is hung up at the station calling the repeater R5 in fig. 40 is released and the loop of wires of the T5 junction circuit is opened to allow relays 3503 and 3504 to release. At this point the connector is returned to the normal position by the operation of the release solenoid through engagement contacts 3527.



   Routing of calls made by the office 86.



   The manner in which calls originating from office 86 are routed will be explained below.



  As shown in figs. 5, 46 and 47 the repeater selectors (connected directly to the preselectors of the satellite office) have access to the two junction circuits going out to the public office, to a junction circuit operated in one direction and to 3 junction circuits Operated in both directions which lead to the main office (office 8) and to 5 local connectors, one of them being the LOC4 connector. To check the operation of the repeater selectors, it has been found advantageous to provide 3 special wires called common occupancy wires. One of these wires is the common occupancy wire 3908 of the public office, associated with the 2 outgoing repeaters, one of them being the OR3 repeater in fig. 39.

   The second which is the thread

  <Desc / Clms Page number 139>

 common of occupancy 3558 of the main office is associated with the trunk circuits that lead to this office (office 8). The 5th common busy wire 3558 is associated with the local controller LOC4 and other local connectors. Each of the common busy wires is kept connected to earth as long as there is a free junction circuit in the circuit. associated group, but it is automatically disconnected from the earth when all the junction circuits of the associated group are occupied.

   Referring again to the OR1 repeater of fig. 17 (the OR3 repeater of fig. 39 being identical to this one) it will be noted that the common occupation wire 1308 ends, through contacts of the relay 1306, at earth connected to wire C entering the repeater. As a result, when the OR1 repeater is put into service, the earth is removed at one point of the conductor 1308 and the conductor is not connected to the earth when all the repeaters are in service. The common occupation wire. 3908 of the office satellite 86 is controlled in the same way.



   Wire C of the T4 junction circuit operated in one direction, which runs from satellite office 86 to main office 8, ends, as shown in fig. 47, in a relay which removes earth at one of the points main office bus common wire 3558 when trunk T4 is in use. Likewise, the common occupancy relay 3501 of the incoming connector IC2 is connected to wire C of the junction circuit T5 and to the incoming connector IC2. As a result, it attracts, to remove the earth from the main office busy common wire 3558, when the T5 junction circuit is in use. by a similar arrangement, the common bus 3858 of the local connector is disconnected from ground at all such points when all trunk circuits terminating at the local connector are in service.

   Common occupancy wires are common to all repeater selectors, such as

  <Desc / Clms Page number 140>

 as SR, as indicated by the common connection symbols thereof.



   Calls from office 86 to the public office.



   It will now be assumed that the subscriber of station A4 in FIG. 46 wishes to put himself in communication with a subscriber of the public office. He therefore picks up his receiver and sends the number of the subscriber requested in the public office, preceding it with the number "0".



   When the receiver at station A4 is picked up, the preselector LS10 operates in the usual way to eliminate a free junction circuit, this one may be the junction circuit shown on the plan and leading to the repeater selector SR. The negative and positive wires entering the SR repeater selector are extended normally through the contacts of relay 3701 and the left windings of the 3733 translator coil to the windings of relay 3702. The relay 3702 therefore attracts when the repeater selector is turned on. put into service which causes the successive attraction of relays 3703 and 3704.

   Relay 3703 places a ground on the incoming wire, to keep the LS10 preselector in the working position, while relay 3704 prepares the circuit of the control solenoid 3718 of the MS marking switch through contacts of the relay 3709 .



   It should be remembered that the connection is established to an incoming primary selector from the main office when the receiver is picked up at the annex office in order to avoid adding a digit to the subscriber number of the annex offices. 8 and 9 when called from the satellite office. This provision is in accordance with normal practice. The relays 3702 and 3703 being attracted, the right windings of the translator coil 3733 are therefore connected to the wires 3741 and 3742 via the rest contacts of the relay 3701.

   Of

  <Desc / Clms Page number 141>

 this causes the 3716 relay circuit to close, this relay being associated with the repeater selector mechanism. The upper bearing of the 3716 relay is connected to wire 3741 while the earth is connected to wire 3742 through the common wire. busy 3558 from the main office and through contacts on relays 3712 and 3713 (unless wire 3558 is disconnected from ground if all trunk circuits to the main office are full).

   Relay 3716 attracts if there is a free junction circuit terminating at the main office, by attracting it connects the junction point of the windings of relay 3715 and the control solenoid 3717, through contacts of the relay. Relays 3715 and Relays 3713 and 3712, to the C3 test brush which is used to test the trunk circuits that lead to the main office. It should be noted that all the contacts in the banks of the C3 balance are connected to earth, except the 4 contacts which terminate the C wires of the junction circuits to the main office. The control electromagnet 3717 therefore works like a buzzer in the circuit comprising the test brush 03 and the contacts on which it engages successively, until the brushes 3700 arrive. on the terminals of a free junction circuit to the main office.

   At this moment the brush 03 is engaged on a contact which is not connected to the earth and the operation of the electromagnet 3717 ceases. At this moment, the relay 3715 which was previously short-circuited by the earth given through the brush C3, attracts in series with the electromagnet 3717 through the contacts of the relays 3713 and 3712 and the earth of the contacts. of relay 3704, By attracting, relay 3715 opens the test circuit and closes with its lower spring the guard circuit of the lower winding of relay 3716;

   it extends the incoming wire 0 set to

  <Desc / Clms Page number 142>

 earth to brush 03 through contacts of relay 3716 and it disconnects the wires 3741 and 3742 from the earthed wire 3747 and from the upper winding of the relay 3716, it extends these through the contacts of relay 3716 and negative and positive brushes to the talk wire of the selected junction circuit to the main office, it can be assumed that this junction circuit is the T5 circuit operated in both directions.

   The common occupancy relay 3501 of the incoming connector IC2 draws into the circuit of wire C when the junction circuit T5 is seized; Relay 3502 also draws into wire 0 circuit through occupancy key contacts 3544. Relay 3502 disconnects the negative and positive wires of junction circuit T5 from the corresponding wires of incoming connector IC2.



   The straight windings of the 3733 translator coil are bridged to the wires of the T5 junction circuit via the negative and positive brushes of the repeater selector group 3700, thereby the line and release relays (which are not shown) of the arrival selector IS6, in fig. 39, in office 8 prepare the operation of the arrival selector. The arrival selectors, at desk 8, are all identical to the primary selector FS5 in fig. 16 except that the shaft springs of these corresponding to spring 1217 of the 9th level (fig. 16) are placed on the 8th level, thereby the arrival selectors, of figs. 38 and 39, absorb the number 8 instead of the number 9 when this is the first digit emitted.



   A prompt-to-transmit tone applied through the coils of the line relay of the incoming selector shown in Fig. 39 is sent over the wires of the T5 junction circuit to the repeater selector SR and from there via the switch. translating reel 3733 to the line of substation A4 which

  <Desc / Clms Page number 143>

 means that the calling subscriber can now start sending the requested number since the repeater selector SR is ready to receive the first digit as is the incoming selector IS6 in fig.39.



   It can be pointed out at this point that since the operation of relay 3716, as described above, depends on the presence of an earth brought by the common occupancy wire 3558 of the main office, this relay does not have not pull when the SR repeater selector is turned on when all trunk circuits to the main office are busy. In this case, relay 3715 attracts immediately since no test circuit closes to attract relay 3716. By pulling, relay 3715 cuts the circuit of relay 3716 to prevent its subsequent attraction, it extends wires 3741 and 3742 to the two upper springs of relay 3716.

   The upper spring of relay 3716 is now connected to the upper winding of this relay to close a surge current feedback circuit, while the adjacent spring of this relay is connected through the stop capacitor 3746 to the wire of the invitation to transmit tone 3745 via contacts of the relays 3713, 3712 and 5711. An invitation to transmit tone is therefore given to the satellite office, in this case, to notify the subscriber of which it can send even though all trunk circuits to the main office are busy, but if a trunk circuit to the main office is free the local prompt tone wire is disconnected from relay 3716 so that this dial tone normally comes from the main office.



   When the subscriber of the office A4 transmits the prefix "0" in order to obtain a connection towards a trunk circuit towards the public office, the relay 3702 interrupts 10 times at its upper springs the bridge placed on the wires 3741 and 3742. Since this bridge currently serves as a guard bridge for the line relay of the incoming selector IS6 in fig. 39 this

  <Desc / Clms Page number 144>

 selector operates to bring its brushes in front of the 10th level of the bank contacts. This operation is of no particular use in the present case since the 10th level of the bank contacts is unused in the arrival selectors of the office 8 as shown in FIG. 4 and as already stated previously.



   Relay 3702 also sends 10 pulses through contacts of relay 3704 to the control solenoid 3710 of the mark switch MS. The first of these pulses passes through contacts of engagement relay 3709 and the following pulses pass through contacts of relay 3707 which draws in parallel with the electromagnet 3718 at the moment when the first pulse is sent and which places a shunt on the contacts of relay 3709 so as to keep closed its own circuit and the circuit of the control solenoid 3718 after the engagement relay 3709 has drawn due to the closing of the switches. contacts 3721 of the MS marking switch.

   The relay 3709 also prepares a control circuit at its lower contacts while at its upper contacts it prepares the circuit of the release solenoid 3719, this circuit is kept open at the contact of the relay 3704 :.



   The relay 3707 also disconnects the ground of the brush 3720 from the mark switch MS during the movement of that brush and it closes the circuit of the relay 3708, thus this one remains attracted during the sending of the pulse train. The relay 3708 disconnects the relay 3701 and prepares the release of the relay 3715 according to the value of the digit emitted as determined by the position taken by the marking switch MS.



   Since the number emitted is the number 0, the 3720 brush advances to its last contacts.



   At the end of the pulse train, relay 3707 releases and opens the circuit of relay 3708

  <Desc / Clms Page number 145>

 and applies ground to brush 3720 thereby closing the circuit of the lower coil of relay 3713 through contacts of relay 3711. Relay 3713 locks to ground wire 3743; it opens the circuit of relay 3715 since relay 3708 has not yet released; it prepares the circuit of relay 3701; he disconnects the test broom 03 from the main office and replaces it with the test broom C1 from the public office;

   it closes the circuit of the discrimination relay 3714 to its lower contacts via the incoming wire EC (grounded by the jumper wire 3731 to the preselector LS10 to allow the discrimination relay to attract and prepare connection to the public office), finally it disconnects the starter wire 3747 from the common occupation wire 3558 of the main office and extends it through contacts of the discrimination relay 3714 to the common occupation wire 3908 of the public office .



   Relay 3716 whose blocking circuit was opened at the lower spring of relay 3715 at the time of releasing this relay remains attracted through contacts of relay 3715 and via common occupancy wire 3908 and contacts of drawn relays 3713 and 3714. Relay 3716 maintains the junction point of the winding of relay 3715 and the control solenoid 3717 connected, through contacts of relay 3713, to test brush C1 . Therefore the 3717 electromagnet attracts again to advance the 3700 brushes until a free junction circuit to the public office is reached, we can assume that this junction circuit is the one that ends at the repeater outgoing OR3 in fig. 49.



  When this junction circuit is seized the brush C1 is no longer connected to the earth and the operation of the electromagnet 3717 ceases. Relay 3715 attracts again through control solenoid 3717 and through contacts of relay 3708, Relay 3715 having again attracted relay 3716 is blocked at the lower spring of the relay.

  <Desc / Clms Page number 146>

 3715 relay and the connection is extended, through 3700 brushes, to the outgoing repeater OR3. The earth of wire C, 3743, is extended through contacts of relays 3715 and 3716 and through a contact of relay of relay lais 3713 and / 3718 to relay 3701.

   Relay 3701 therefore pulls to short-circuit the windings of the translating coil 3733 and to close a new guard circuit of relay 3715 to the 0 grounded wire, without the aid of the upper contacts of relay 3704. Relays 3702 or 3704 release leaving relays 3701 and 3713 or 3716 in working position in the repeater selector. The connection is maintained by the earth placed on wire G of the starting repeater OR3, the incoming wire C of the repeater selector being extended through the brush C1 to wire C of the repeater OR3. The MS marking switch releasing solenoid 3719 operates through contacts of relay 3709 when relay 3704 releases.

   As a result, the MS switch returns to the normal position and the relay 3709 releases.



   The calling subscriber can now send by means of his call dial the digits of the desired number in the published office, these being repeated by the outgoing repeater OR3.



   The calling subscriber can set up an information call through the outgoing repeater OR3 and the pre-selector LS9 as has been explained for the repeater OR1 of fig. 17 and the preselector LS1 associated with it.



   When the calling subscriber hangs up his receiver at the end of the communication with the public network, the release of the ORS repeater has the result of removing the earth of the 0 wire associated with it. As a result, the relays which have drawn into the repeater selector SR release and the preselector LS10 returns to the rest position.

  <Desc / Clms Page number 147>

 



   Outgoing calls from satellite office 86 to office 8.



   In order to explain the operation of the equipment of the satellite office 86, it will be assumed: that the subscriber of set A4 has picked up his receiver and that the operations which have already been described have been carried out, that the first digit transmitted is the number 8 instead of the number 0 and that it calls a subscriber of the office 8 in the case where the sixth digit transmitted is other than the number 6.



   Since the first digit transmitted is the digit 8, the brush of the MS marking switch advances to the 2nd associated contact. Under these conditions when earth is reapplied to brush 3720 at the time of releasing relay 3707 the circuit of relay 3711 closes through contacts of relay 3710. Relay 3711 closes its blocking circuit at its lower contacts. internal through relay 3710 and earth taken from the upper internal spring of relay 3704. Relay 3710 does not, however, draw into the blocking circuit as long as earth is applied directly to the winding of relay 3711 as it does. is now done by means of the 3720 broom.

   The 3711 relay also closes an additional blocking circuit for itself at its inner top contacts through the inner contacts of the 3709 engage relay to prevent pulling of the 3710 relay until the mark switch has returned to normal. normal position.



   Relay 3711 also closes through contacts of relay 3710 the circuit of release electromagnet 3719. Release electromagnet 3719 returns brushes 3720 to the rest position; therefore the engagement contacts 3721 open and cut the circuit of relay 3709.

   Relay 3709 opens the blocking circuit of relay 3711 at its lower contacts for

  <Desc / Clms Page number 148>

 allow relay 3710 to pull while using the inner lower contacts re-connects the 3718 control solenoid to allow it to operate again, Relay 3710 now draws into the blocking circuit of relay 3711 to open the circuit of the release solenoid 3719 and to connect the junction point of the windings of the relays 3710 and 3711 and block the shunt of the relay 3710 when the next digit is output. when the next digit is transmitted the control solenoid 3718 moves the brush 3720 to the corresponding contacts on the bank.

   Since it has been assumed that the call is intended for a line connected to office 8, the next digit is any one of the digits other than 6. In this case, no switching will take place in the repeater selector afterwards. that the 3720 broom will have returned to rest. when relay 3707 releases $ it disconnects its own winding and that of control solenoid 5718 from the power wire, the result is that the digits which are sent next have no effect on the start switch. quage MS, they are all repeated at the top contacts of line relay 3? 02, as previously said, to the main office switchgear 8.



   It should be noted that the lower contacts of relay 3711 also close the circuit of relay 3706 which will be activated to block malicious calls as will be described later. This relay attracts and blocks itself through contacts of relays 3705 and 3701 and through contacts of occupancy key 3732. Relay 3706 establishes an additional connection to the earth of wire C 3743 and a connection identical in parallel with that established at the upper winding of the auxiliary relay 3704 to keep the relay 3718 attracted without the backup of the relay 3704 while at its upper contacts it prepares the bridging of the high resistance relay 3705 safe

  <Desc / Clms Page number 149>

 wires 3741 and 3742.



   Calls in transit from office 8 to office 9.



   At this point it can be pointed out that in the case where the calling subscriber establishes a call to office 9 the only difference in the operation which has been described previously is that the relays 3710 and 3711 attract in series at the end of the transmission. of the first number 9 when the 3720 brush has engaged on the 9th bank contact instead of the Sème. Relay 3711 is made slightly delayed on pull as shown in the plan to allow relay 3710 to attract first and then to prevent unwanted pull of releasing solenoid 3719. MS marking switch does not work because the circuit of control solenoid 3718 is held open at the lower contacts of relay 3709 after releasing relay 3707 as previously described.

   It should be noted that provision has not been made for the repeater selector SR to work when the direction of the current is reversed in the line when the called subscriber answers since this operation is not necessary in the case of 'calls originating in the satellite office.



   When the calling subscriber hangs up his receiver at the end of the communication, relay 3702 releases to open the bridge placed on the conversation wires and on the wires of the junction circuit used towards the public office, it therefore allows the release. switching devices that have been commissioned at the remote office.



  Relay 3703 and relay 3704 release as a result of releasing relay 3702. Relay 3704 allows relays 3710 and 3711 to be released when it removes brush ground 3720 from MS marking switch but relays 3715 and 3716 remain. momentarily attracted since the remake 3706

  <Desc / Clms Page number 150>

 is blocked as described above. When releasing relay 3703, relay 3705 is placed on wires 3741 and 3742 through the contacts of relay 3706. The high resistance relay 3705 therefore draws wires from the junction circuit to the other in the loop. to open the circuit of relay 3706. Relay 3706 therefore releases and allows the release of relays 3715 and 3716 of the repeater selector as well as the reset of the preselector LS10. The connection is therefore released.



   Local calls to satellite office 86.



   In the event that the subscriber of set A2 calls a local line in satellite office 86, the operations are identical to those described above with regard to a call to main office 8, the relay 3711 then attracts and brings the NE marking switch back to the normal position * As a result, relay 3710 attracts as described above.



   When the 2nd digit, 6, is emitted, the 3720 brush engages on the 6th contact of the bench. Therefore, when the relay 3707 releases the control electromagnet 3718 is put out of service so that it no longer works under the action of the other impulses, the connection of an earth to the brush 3720 results in closing the circuit of the lower winding of relay 3712. Relay 3712 is blocked at wire 0 3743. As can be seen by consulting the plan, relay 3712 performs a switching operation identical to that which was described for relay 3713. As a result, relay 3715 releases to allow a new search while the local broom C2 is substituted for the broom of the main office C3.

   In addition, the circuit of the upper winding of relay 3716 is transferred to the common occupancy wire.

  <Desc / Clms Page number 151>

 3858 of the local connector and therefore relay 3716 remains attracted or not depending on whether the local connectors are occupied or free. If all connectors are busy and therefore the 3716 start relay cannot stay pulled, the 3715 relay pulls alone and a busy tone is connected from the 3743 busy tone wire through contacts of the re. - leaves attracted 3709 and 3713. On the other hand, if one or more of the local connectors are occupied (as is usually the case) the relay 3716 remains attracted in the circuit of the common busy wire 3858 and maintains the circuit. control solenoid 3717 connected to brush C2.

   The brushes 3700 therefore rotate until they have reached a free local connector which can be assumed to be the one shown in fig. 48. When this connector is found the search movement ceases and relay 3715 draws again through contacts of relay 3708 which released. Relay 3701 attracts through contacts of relay 3712 and contacts of relays 3715 and 3716 to short-circuit and disconnect the windings of the translatrioe coil 3733 and thereby extend the calling line directly to the local connector LOC4 of fig. 48. Relays 3702 to 3704, 3706 to 3710 and 3711 release and the MS switch returns to idle, relays 3701, 3710 to 3712, 3715 and 3716 remaining pulled into the repeater selector.



   In the local connector LOC4 the relay 3802 attracts when the connector is put into service and closes the circuit of the relay 3803, then the relay 3804 attracts through the lower contacts of the relay 3803 and through the lower contacts of the relay. relay 3809. Relay 3803 places a ground through contacts of the occupancy key 3831 on the incoming wire C so as to maintain the connection established through the selector repeater SR.

  <Desc / Clms Page number 152>

 



  Relay 3801 removes ground at one point of common bus 3858.



   When the calling subscriber transmits the tens digit of the requested number, the ascending electromagnet 3815 operates through contacts of relay 3805 which initially attracts through the engagement contacts 3819 and the lower contacts of relay 3803. The balances 3800 are thereby brought in front of the desired level of bank contacts.



   At the end of the ascent movement, the relay 3805 releases and prepares the command for the rotational movement.



   When the units digit is output, the 3816 rotating electromagnet operates and rotates the 3800 brushes until they engage the terminals of the called line. The occupancy test is performed by relay 3810 whose circuit, which borrows brush C, is controlled by relay 3811 which is itself controlled by relay 3812. In the event that the called line is busy, busy tone from wire 3820 is returned to the line and relay 3810 locks out when releasing relay 3811.



   On the other hand, in the case where the called line is free, relay 3813 attracts wire 0 in the circuit when releasing relay 3811 to attract relay 3814.



   Inrush current is sent when relay 3814 attracts; this current is supplied through common wire 3820 through the contacts of relay 3809.



   Relay 3809 attracts when the called subscriber answers, relays 3807 and 3808 then attract successively. Relay 3808 bypasses the lower contacts of relay 3809 which attracted due to the pull of relay 3809. The connector remains in this state until communication is terminated.

  <Desc / Clms Page number 153>

 



   At the end of the conversation, the two subscribers hang up their receiver. In the event that the calling subscriber hangs up first, relay 3802 releases immediately, this is followed by the delayed release of relay 3803, itself followed by releasing of relay 3804 since the circuit of its upper winding is open when relay 3803 releases.

   Relay 3814 releases when its blocking circuit is open at the lower contacts of relay 3804; relay 3807 releases as a result of releasing relay 3814 and therefore relay 3808 also releases, finally relay 3809 releases when its circuit is open to engagement contacts 3820 when the connector returns to the rest position under the action of the releasing electromagnet 3817, the circuit of which closes through the engagement contacts 3818, when the relay 3804 releases.



   On the other hand, in the case where the called subscriber hangs up first, the release of relay 3807 and the release of relay 3808 is followed by that of relay 3804 which opens the circuit of relay 3814, it disconnects the brushes 3800 and by therefore clears the called line. Under these conditions, the connection is released as a result of releasing relay 3803 when relay 3802 releases when the calling subscriber hangs up his receiver.



   In the SR repeater selector due to the removal of ground from wire C when relay 3803 of the local connector LOC4 releases, relays 3701, 3712, 3915 and 3716 release and the SR repeater selector returns to the rest position.



     Block malicious calls.



   As previously mentioned, a characteristic of the invention consists in that improved devices have been provided to allow

  <Desc / Clms Page number 154>

 a subscriber who receives malicious calls to block the established connection when he wishes until the staff serving the annex office has been able to retrace the route followed to establish the connection and discover the line which made this call.

   For this purpose, special circuit arrangements have been made in the switching apparatus and a number of special repeaters such as the blocking repeater shown in fig. 50 were installed in each of the annex offices for the temporary connection of any line of a subscriber of the annex office who had to complain that he was receiving malicious calls.



   The blocking repeater of fig. 50 has been shown as being temporarily associated with the line of the station A1 of figs. 3 and 16, the line of which has full service in office 9. It will be understood that the subscriber's line wires are normally connected by means of 2-conductor flying wires in the distributor to the multiple bank of his. line into the connector and that the preselector serving that line is ordinarily connected to the negative, positive, and C wires of the connector's multiple bank by means of a 3-conductor jumper wire. The blocking repeater in fig. 50 is connected by a cable to the distributor.

   Two of these terminals are connected in the distributor to the subscriber line by means of two-conductor flying leads, such as 4025, while 4 terminals, 4000, are provided and correspond to the wires of the multiple bank of the connector to which the 4-conductor flying wire 4021 can be connected to connect the blocking repeater to the contacts of the connector banks, such as 1250, and to the multiple thereof (not shown). The negative, positive and C terminals of group 4000 are connected to the preselector by means of a 3 conductor jumper wire such as 4022.
 EMI154.1
 



  If we assume that the repeater of iet cage

  <Desc / Clms Page number 155>

 of fig. 50 has been inserted into the line of subscriber A1 by the temporary flying connections which are shown in the plan, the operation when a call is received or made on this line will be described below.



   If it is assumed that a connector (such as the local connector LOC1 in fig. 23) stops on terminals 1250 of the line of station A1 when this line is free, wire C is extended by means of the wire 0 of the flying connection 4021 and 4022, which gives the cut to the preselector LS2 and allows the test relay 1917 of the connector to attract and cause the line to be switched on.

   When the intermittent inrush current is sent through the connector, relay 4001 attracts through the capacitor and contacts of relay 4007. Relay 4001 attracts relay 4002 to short circuit the windings of the translator coil 4015 and thereby connect the line from station Al directly to the negative and positive terminals of group 1250 for the duration of the inrush current being sent. Relay 4002 attracts relay 4003 which locks to the grounded C wire and prepares the circuit for relay 4010.



   After each call period, the relay 4001 allows the release of the short-circuit relay 4002 and reintroduces the translator coil 4015 in circuit.



   When the calling subscriber answers, by picking up his receiver, the relay 4006 draws into the circuit of the called line in series with the impedance coil 4005 and the relay 4004, By attracting, the relay 4006 causes the relay 4007 to attract to disconnect relay 4001 and to prepare the circuit of relay 4009. Relay 4006 also blocks the straight windings of the translator coil 4015 on the conversation wires which attracts the call cut-off relay from the connector and causes the attraction of the relay power supply in this device to give response supervision.

  <Desc / Clms Page number 156>

 



   In the event that the call to the line of set A1 is made by the operator of the passing table and the subscriber of set Al wishes to call it back, he can do so by manipulating his call dial, which releases relay 4006 one or more times. Each time the relay 4006 releases, at its upper contact, it opens the circuit of the connector supply relay which therefore releases momentarily one or more times to recall the attendant from the annex office as has been described previously.



   In case]., Call is received from the public office. and that the subscriber of the set Al wishes to transfer the connection to the line of another local subscriber, he momentarily pushes the button of his set which unbalances the called line and causes the attraction of the relay 4004, this one applies a ground on the positive talk wire which unbalances the current in the 1936 transfer control relay windings of the connector. This causes the connector to transfer as previously described. The resumption of communication to the main office is accomplished when the subscriber of the set Al pushes the button on his set again.



   When the conversation is finished, the subscriber of the set Al hangs up his receiver. Therefore, the relay 4006 releases and at its upper contacts opens the circuit of the connector supply relay, which causes the line to be released as described previously.



  Relay 4007 releases and switches relay 4001 back on.



   When the subscriber of set A1 picks up his receiver to make a call, relays 4006 and 4007 attract as before and relay 4006, when it attracts, closes a bridge to its upper contacts, which makes the relay operate. LS2 preselector in the usual way to extend the connection. The pulses are repeated at the upper contacts of relay 4006.

  <Desc / Clms Page number 157>

 



   The extended connection is released when the subscriber hangs up his receiver, allowing relays 4006 and 4007 to release.



   From the above description of the operation of the blocking repeater it can be seen that the normal operation of the line of station A1 is not disturbed by the temporary introduction of the blocking repeater into the communication.



   It can be assumed that the subscriber of the set A1 in FIG. 50, when answering a call, realizes that the caller is one of those who make malicious calls and that he refuses to be identified. The subscriber of set A1 can block the established communication by pushing the button on his set and manipulating his call dial at the same time. It will be remembered that pushing the button alone is used in the case of an information call and that manipulation of the call dial during an incoming call is normally used to call back the office attendant. Annex. when the two operations are performed simultaneously, the connection established to the called line is blocked as will be shown.



   When the button of the station Al is pressed, the relay 4004 attracts and makes the relay 4008 attract. At its upper contacts, the relay 4008 unbalances the circuit of the connector and prepares the circuit of the relay 4009. Therefore when we act on the dial of call from station Al by sending a number, number 1 for example, relay 4006 momentarily releases and closes the circuit of relay 4009 through the contacts of relays 4007 and 4008.



  With relay 4009 attracted, when relay 4006 attracts again, the circuit of the upper winding of relay 4010 closes through contacts of relay 4003 (the latter attracts for each incoming call and blocks

  <Desc / Clms Page number 158>

 to wire C) and through contacts of relay 4009. Relay 4010 attracts and blocks through the contacts of the associated release key. This relay also turns on signal light 4016 and sounds alarm 4017. Relay 4010 also connects the multi bank EC wire from the connector to the positive terminal of a 90 volt booster battery. The negative of this battery is earthed and its polarities are therefore opposite to those of the battery supplying the office. This connection is established through limiting resistor 4012.



  As a result of this connection, a strong current impulse passes through wire C and brush C of the connector.



  This current pulse ends when the delayed pull relay 4011 attracts.



   When the calling station button is released, relays 4004 and 4008 return to idle. The relay 4009 releases following the end of the sending of the pulses emitted by the call dial. However, relay 4010 remains attracted and blocked to keep alarm lamp 4016 on and to keep the circuit closed to alarm device 4017.



   In the local connector LOC1 (fig. 23, if it is assumed that this connector is the one that was used) the upper winding of the blocking relay 1916 is connected through contacts of the relay attracted 1918 to the EC brush of group 1900.- Although this relay is a marginal relay, i.e. it does not attract when the EC sweeper encounters an earth in the case of a call to a restricted service line, this relay attracts many - due to the high voltage pulse transmitted by the repeater in fig. 50. By attracting, the 1916 relay closes its blocking circuit through the contacts of the 1926 occupancy key.

   Relay 1916 also opens the line relay bridge by removing ground from the lower winding of relay 1902 and

  <Desc / Clms Page number 159>

 
 EMI159.1
 41747.) such that it closes the blocking circuit of relay 1906 so that the connector is kept in service as well as the devices which precede it.



   In the event that the call that was blocked to the line from extension 1 is an incoming call from office 8, removing the earth from the lower terminals of relay 1903 of the local connector LOC1 relays the blocking through the junction circuit to to the repeater of office 8 to cause the blocking of the local switches, but if the call passes in transit through office 8 and comes from satellite office 86 the blocking is relayed to the repeater selector put into service at satellite office 86 as we will show it later.



     'The maintenance worker in office 9 is alerted by the signal given by common device 4017.



  He is guided to the repeater which has been blocked by the individual signal 4016. The agent then takes his steps to retrace the path followed by the communication which was established and discovers the line which made the call since the connection is maintained until the agent intervenes. when the call has been traced, the attendant activates the release key associated with the lower winding of relay 4010 of the blocking repeater, this relay therefore releases and opens the signaling circuits, at the same time it opens the circuit of the relay 4011 which allows it to release. The blocking repeater is therefore no longer in the blocking position.



   After following the call to its starting point, the agent can release the blocked switch by momentarily activating the occupancy key 1926 of the connector shown in fig. 23. The local switches preceding it in the selection train are released when wire 0 is opened at the upper contacts

  <Desc / Clms Page number 160>

 of the occupancy key and relay 1916 releases when its blocking circuit is open at the upper contacts of the occupancy key. Relay 1004 circuit opens when relay 1916 releases; as a result the connector returns to the normal position. The line of the station A1 in FIG. 50 is therefore released and the relay 4013 releases.



   In order to explain how malicious calls from another office are kept blocked, reference is made to repeater R1 in fig. 21.



  This repeater is identical to the others, except for the repeater selector of the satellite office 86. It will be recalled first of all that the relay 1709 of the repeater R1 attracts each time the relay 1702 attracts when the repeater is put into service and this relay is blocked. - even by means of the earth taken from the contacts of the occupancy key 1716. It closes a multiple connection to the earth to the incoming wire C to keep the local switches blocked without the back-up of the relay 1702. It will be recalled to more that the relay 1710 is connected to the outgoing conversation wires when the receiver is hung up and that it attracts normally to release the relay 1709 and to allow the release of the established connection.



  However, in the event that a malicious call is made through the repeater and that call is blocked, opening the line relay bridge in the connector of the remote office prevents the release of the relay 1710 and the connection remains blocked. In addition when the blocking occurs at the connector and the line relay bridge is opened first, the relay 1704 of the repeater R1 releases and closes the circuit of the upper winding of the relay 1708 in parallel with the relay 1702 and to through contacts of relay 1706.

   This relay draws and disconnects the earth from the winding of the relay 1701 which returns the blockage through the junction circuit

  <Desc / Clms Page number 161>

 precedent in the case where the repeater has been reached via a trunk circuit between offices.



  This last feature has no particular utility in repeaters employed in office 9 but is very necessary in repeaters employed in office 8 since calls pass in transit through this office between offices 9 and 86.



   It should be noted that the repeater Rl automatically returns to standby as soon as the maintenance employee has returned the blocked connector to the normal position because the line relay of the arrival selector of the remote office is again connected to the line to allow the pull of relay 1710 and release of relay 1709.



  Relay 1708 releases when its blocking circuit is opened by relay 1701. Relay 1701 is therefore connected again to the incoming wires in series with the office battery.



   The repeater R1 can be unblocked locally by momentarily actuating the occupancy key 1716 in the event that the relay 1710 does not attract again when a malicious call has been detected or in the event that the repeater does not return to idle. at any time which may occur in the event that an office-to-office branch circuit fails or one of the wires is cut at the far end.



   Referring now to the repeater selector SR of figs. 46 and 47 of the office 86, it will be recalled that the relay 3706 attracts and blocks through contacts of the occupancy key 3732 when the relay 3711 attracts when the first digit emitted is the digit 8 or the ohter 9 which is the characteristic of a call between two offices. When the call is repeated in main office 8, the SR repeater selector is working

  <Desc / Clms Page number 162>

 like an ordinary repeater to send back the pulses, it remains on for the duration of the communication and in this case the relay 3706 is not released and disconnected by the relay 3701 as it is in the case where the The call should loop normally through a local connector.

   When a call is established through the main office, the high resistance relay 3705 must therefore pull to open the circuit of relay 3706 when the calling subscriber hangs up his receiver, otherwise the connection would be blocked.



   The blocked connection can be released by momentarily activating the occupancy key 3732 in the event that the 3705 relay does not attract when removing the block at the remote office.



   It will be observed that the local connector of FIG. 48 is provided with a marginal relay 3806 which attracts under the action of an impulse as does the relay 1916 of the local connector shown in fig. 23 to lock itself through the contacts of the occupancy key 3831 and for close the blocking circuit of relay 3803, as a result the local connection is blocked because an earth is now maintained on the incoming C wire and the connector cannot return to the rest position. However, the circuit of relay 3802 does not pass through contacts of relay 3806 since the connector of fig. 48 is a local connector and is never used for calls between two offices.



   The relay 3521 of the incoming connector IC2 of figs. 42 and 43 has the same arrangement of the contacts as that which has been described for the connector of FIG. 23 and this for the same purpose. The locking at the connector of figs. 42 and 43 disappear when the occupancy key 5544 is momentarily activated.

  <Desc / Clms Page number 163>

 



     Blocking malicious calls in the case of restricted service lines.



   As previously stated, the blocking repeater in fig. 50 functions to block a malicious call when the called subscriber performs two very distinct maneuvers: 1) when he pushes the earthing button from his station, 2) when he operates the call dial to send impulses. It has also been explained that the reason for this maneuver is that each of them separately is called upon to produce a specifically different effect.



   When the blocking repeater in fig. 50 is used for a restricted service line, it is not possible to use the earthing button of this station since it is not fitted with one, therefore, operating the call dial of a restricted service station during the course of an incoming call is considered sufficient to indicate that the call should be blocked; it is therefore not necessary for this purpose to provide the set of a subscriber with restricted service with an earthing button. For this reason the terminals 4014 are joined together when the blocking repeater of fig. 50 is associated with a full service line. The 4014 terminals being joined together the contacts of the relay 4008 are short-circuited, the relay 4008 causes the series relay to attract to cause the blocking of the communication when the relay 4010 attracts.

   Additionally, terminals 4013 are combined when the blocking repeater is used for a restricted line; it places an earth normally on the EC wire to prevent the establishment of a communication to the public office, while allowing the earth to be removed and causing the connection of the booster battery when the 4010 relay operates after the call was blocked.

  <Desc / Clms Page number 164>

 



   Conference service.



   The manner in which the conference service is given in the annex office will be explained in connection with the conference unit of fig. 51. This unit is provided with terminals as shown, so that it can be associated with any number of lines, these lines can be changed at any time as desired. The equipment that is found immediate-. to the right of the dotted line in fig. 51 is - associated with the bank contacts of the connectors by means of which one is connected to the conference unit when the special number for this service is issued, it is common to as many individual circuits as desired. One of these individual circuits is shown to the left of the dotted line. Each individual circuit can be made available to a separate subscriber.

   It can be used normally, regardless of the conferencing unit as the circuit is arranged so that the lines are interconnected for conference service only when desired. Line from station B is associated with the individual circuits by means of flying wire 1407.



   The terminals of connector 4150 through which the line of station B is reached are connected via a 3-conductor jumper wire 4121 to the negative, positive and C1 terminals of group 4109 and the pre-selector of the line. of station B is connected by means of the 3-conductor jumper wire 4122 to the positive, negative and C2 terminals of group 4109.



   For the purpose of explaining the operation of the conference unit, it will be assumed that the conference number is sent by a subscriber who wishes to initiate and participate in a conference. When the connector relays (in fig. 23 for example) reach the terminals, 4100,

  <Desc / Clms Page number 165>

 relay 4105 draws into the circuit of wire C and through brush C of the connector in series with the test relay of this device. Relay 4105 opens the circuit of normally pulled relay 4106 and closes the circuit of relay 4104. Relay 4106 is sufficiently delayed on release that it can remain pulled until the switching relay of the switch has pulled and closed. the circuit sending the inrush current and that the inrush cut-off relay of the connector has had time to draw through the contacts of the drawn relay.

   When relay 4106 releases, it extends the incoming chat wires to the conference unit's common talk circuit. Impedance coil 4111 is plugged into these wires for the purpose of keeping the connector power relay attracted which is necessary to keep the connection closed through this device.



   When relay 4104 attracts, it extends a ground to each of the individual line circuits.



  Extending ground to each individual line circuit, as shown, results in pulling relay 4101. Relay 4101 disconnects wire C1 from wire C2 (wire C of preselector LS) and connects it to the earth thereby placing a guard polarity on terminal C of group 4150. The line of station B is therefore marked as being occupied in the benches of the speakers. Relay 4101 also transposes the line from station B to the individual call circuit through the contacts of relay 4102. The inrush current supplied by common wire 4112 now flows through the line for station B, the return circuit to the battery pole which is not grounded being closed through the upper winding of relay 4102.

   The relay 4102 is identical in construction and operation to the. inrush current cut-off relay

  <Desc / Clms Page number 166>

 which usually equips the connector.



   At the same time grounding the other starter wires associated with starter relay 4104 causes the individual line circuits to function identically, hence all lines which have conference service are called at the same time. It should be noted that the switching of the lines to the conference circuit interrupts any conversation which may be in progress on one of the lines having this service; this characteristic is given intentionally because it is recognized that a conference can only be called if it is open to discuss a matter of considerable importance.



   When the subscriber of set B picks up his receiver, relay 4102 attracts and is blocked during the boot wire; it places the delayed relay 4101 under the control of the relay 4103 and it extends the line from station B to the individual wires associated with the relay 4103 which are connected to the common conversation wires. Relay 4103 pulls and closes the blocking circuit of relay 4101 before that relay has had time to release. Relay 4103 also closes the multiple circuit of relay 4105 such that it keeps relay 4105 engaged and relay 4106 released.



   The subscriber of set B can now enter into conversation with the subscriber who made the conference call and with the other subscribers who have this service, when they answer and they are connected on the common circuit.



   After participating in the conference, the subscriber of set B can withdraw before it is over in the event that he has to attend to something else and finds that it is no longer necessary. for him to stay tuned. He therefore hangs up his receiver, so relay 4103 releases and opens the circuit of relay 4101.

  <Desc / Clms Page number 167>

 



  Relay 4101 releases and transfers the line from station B to the associated preselector and to the multiple of the connector bank. Relay 4102 remains drawn into the circuit of the individual start wire controlled by relay 4104 and thereby maintains the circuit of relay 4101 open.



   It can be noted that the internal spring of relay 4101 disconnects wire C from preselector LS6, it applies a ground to wire C of the multiple of the connector banks in order to allow the release of a communication already in progress in the case where. a conference call is made when the line of extension B is engaged in an outgoing communication.



  * The conference circuit is maintained in service as long as any of the subscribers having this service at its receiver off-hook since the circuit of relay 4105 is kept closed by any of the wires C of the connector which was used to establish the conference or by the upper internal contacts of the line relay of any of the lines having the conference servioe.



   In the event that it is desired that no subscriber can engage in a conference except through one of the lines of this service, the flying wire with 2 conductors 4108 is deleted, This flying wire being deleted, the calling subscriber is not able to initiate a conference through the connection established by means of the calling connector since the conversation wires in and coming from terminals 4100 do not extend through the common conference wires. By this arrangement, conferences can only be initiated by one of the subscribers, the subscriber of set B for example,

  <Desc / Clms Page number 168>

 
When the subscriber of station B initiates a conference call, he picks up his receiver and activates the LS preselector.

   It then sends the number of the conference service: From then on when the relays 4105 and 4104 attract and cause the attraction of the individual relay 4101 which transposes the line from set B to the conference circuit, the connection established to the This service's terminals is released and relay 4102 immediately draws in to close the talk circuit to the conference unit.



  Relay 4103 therefore attracts and closes the blocking circuit of relay 4105 to keep relay 4104 attracted.



   If it is definitively decided when the conference unit is mounted in an installation that only a specific group of subscribers will be able to participate in the conference service, relay 4106 and impedance coil 4111 can be omitted since they are not required. only in the event that a line which is not part of this group is authorized to be connected to this circuit.


    

Claims (1)

CLAIMS. ---------------------------- 1. A telephone system comprising a main office and a private system made up of several secondary offices in which the calls ending in the private system and which come from the main office are directed to only one of the secondary offices where they are extended if necessary to a other sub-office, while outgoing calls to the main office and originating from any sub-office are established through lines which directly connect the main office and the sub-office in question. 2. A telephone system comprising a main office and a private annex office and provided with the means which allow only a certain number of subscribers of the private office to receive calls from the main office, in which when calls come from the main office. main office, a signal is transmitted step by step through each switching stage to cause circuit modifications in the final selector which make it possible to carry out an additional test of the subscriber line according to which communication cannot not be established if the line is of restricted service, a busy signal being sent in this case to the calling subscriber. 3. A telephone system comprising a main office and a private annex office and provided with the means which allow only a certain number of subscribers of the private office to make calls to and receive calls to the main office, in in which the discrimination between restricted and full service lines depends on two different and independent states of the subscriber line circuit, one of them in the case of a call from the main office and intended for a restricted service line prevents extension to the called subscriber and the other in the case of a call <Desc / Clms Page number 170> to the main office prevents the junction to this office from being put into service. 4. A telephone system comprising a private annex office having direct connections to a number of main offices in which calls terminating at the private annex office are extended through incoming circuits to connection circuits comprising a searcher. and a selector, the incoming circuits being divided into two groups according to the origin of the calls which they send and certain groups being arranged so that a signal is transmitted through the different selection stages from the connection circuit which has been activated to characterize the type of incoming call and to determine whether or not the called subscriber is authorized to receive such a call. 5. A telephony system in which the lines leading to a central office are divided into two classes which are distinguished by the absence or presence of polarity on one of the wires of a line circuit associated with each of these, this polarity is active during the establishment of the incoming connection because it causes the recording of the class of the call in each selection stage and that at the end of the selection it causes a test which determines whether the called line is authorized to receive the call in question. 6. A telephone system in which the class character of an incoming call into the office and the offer of a call to a busy subscriber is given by the transmission of a signal through a connection control wire, the characteristic signal being transmitted during the establishment of the connection to attract a relay which is then disconnected to allow the transmission of an offer signal which is transmitted when the connection is established and which attracts a second relay . 7. A telephone system comprising several remote positions / <Desc / Clms Page number 171> machine in which each position is associated with a certain number of searchers having all access to the same group of lines and intended to be selected and put into service by a manual control carried out by the operator, this manual control being provided in such a way that it temporarily brings together a starting circuit, common to all the lines, and the particular position where when a call appears on one of these lines the selected searcher is immediately put into service to search for the calling line . 8. A telephone system comprising several operator positions in which each position is associated with a certain number of researchers all having access to the same group of lines and provided with a position starting circuit designed to be connected. to a starting circuit common to all the lines, the association of a position starting circuit and the common starting circuit being carried out by means of a distributor following the selection by the operator of a researcher free from this position. 9. A telephone system comprising a main office and a private annex office in which incoming calls and certain outgoing calls from the private annex office are served by an operator and in which facilities are provided for the operator's call back afterwards. that a communication has been established either automatically if the called subscriber does not answer within a determined period or by operating the subscriber's call dial. 10. A telephone system having facilities for tracing to the line of the calling subscriber the path followed during the establishment of a communication in which a group of control relays is individually associated with the line of the telephone. 'subscriber who wishes to enjoy this privilege and under specific control exercised by the subscriber, the relay group can keep the selection train in service <Desc / Clms Page number 172> which connects the two subscribers, after the caller hangs up his receiver. 11. For use in telephone systems a final selector in which the release of the connection is placed under the control of the calling subscriber, but in the event that the called subscriber hangs up first, a guard polarity is removed for the called line in the banks of the final selectors having access to it, from where the called line is free for any use even if the final selector is not released. 12. to be used in a telephony system an end selector capable of performing a search in a group of lines, in which if all the lines of the group are found busy the switch stops on the last line and in which the the subscriber who establishes the connection can then establish a telephone connection with the called subscriber and offer the call. 13. A telephony system as claimed in claim 1 in which provision is made for establishing communications between the private system and a second private system connected to a second main office but in which calls cannot be routed from the first main office. to the second private system through the first private system. 14. A telephony system as claimed in claim 1 in which the incoming calls are routed by an operator through connection circuits which include an answering switch and a calling switch, the release of the calling switch taking place either under operator control, independently of the answering switch, in order to allow the operator to transfer a call from one local line to another local line, either by releasing the answering switch. <Desc / Clms Page number 173> 15. A telephony system as claimed in claim 1 in which the incoming calls are routed through an operator by means of connection circuits which include an answering switch and a calling switch, in which the answering switch has access to a telephone. group of selectors by means of which outgoing calls and local calls can be made, so if a local subscriber receives busy tone when trying to establish a connection the operator can make it by means of the answer switch when the line is free and connect the calling subscriber to it using the call switch. 16. A telephony system as claimed in claim 1 in which outgoing long distance calls are set up by an operator by means of a trunk line circuit comprising a time device keeping the line guarded against being put into service by a second. operator for a determined period of time, long enough to allow the devices in the distant office to relax. 17. A telephony system as claimed in claim 1 wherein a subscriber of the private system engaged in communication with the public office can establish an information communication to a second local subscriber via a final selector if the initial call comes from the public office or through the outgoing repeater if the initial call originated in the office. private. 18. A telephone system as claimed in claim 17 in which the actuation of a key by the subscriber of the private system interrupts the connection established on the conversation wires and connects them to a transfer circuit which makes it possible to establish a local call while <Desc / Clms Page number 174> that the line to the main office remains blocked. 19. A telephone system as claimed in claim 1 and having facilities enabling certain subscribers of the private system to set up conference calls in which, during a conference call, the lines which participate in the conference are connected to a conference unit, when a subscriber participating in the conference picks up his receiver maintaining the connection between the line and the unit is placed under the control of the line relay, thereby the subscriber can withdraw from the conference conversation when he wishes. 20. A telephone system as claimed in claim 1 in which the private system comprises a repeater selector, having access to three groups of lines which, when it is put into service, is arranged to perform the search for a free line in one of the groups according to the succession of digits received either to establish a connection to this line or to release this line and search for a free line in one or the other of the two remaining groups and establish a call to it. 21. A telephone system as claimed in claim 20 in which the ability to reach lines in a group is indicated by a polarity applied to a wire common to all lines, so if all lines in the group are busy, busy tone is transmitted. to the calling subscriber and the switch search is deleted. 22. A telephone system as claimed in claim 2 or 4, in which all the intermediate switches of the selection train are provided with a relay which attracts under the action of the signal to transmit an identical signal to the next selection stage, in the final selector ce <Desc / Clms Page number 175> relay attracts to open the test circuit and transmit the tone (Unoccupied to the calling subscriber if the called subscriber is a restricted service subscriber. 23. A telephone system as claimed in claim 22 in which the signal comprises a current pulse, transmitted on an additional wire of the selection train 'through a central office, and also includes the unbalance of the line wire when the signal is to be transmitted on the line which brought together two secondary offices of the private annex office. 24. A telephone system as claimed in claim 22 in which the attraction of this relay prepares the attraction circuit of a second relay which attracts under the action of a given polarity by the line circuit of the called subscriber, if the latter is a subscriber to restricted service, to prevent the telephone connection from being established to the called line and to transmit the busy tone to the calling subscriber. 25. A telephone system as claimed in claim 3 in which during an outgoing call to the main office an automatic switch is brought to a particular level to search for a free line to the main office, on this level the test circuit is connected to the wire of the line circuit to which the discrimination polarity is or is not applied, therefore the test circuit closes and the switch operates in the usual way or the test circuit remains open and the switch cannot put an outgoing line in service. 26. A telephone system as claimed in claim 5 in which during the establishment of a communication the applied polarity causes a relay of the first selection stage to be drawn which serves to apply an iden- / polarity. <Desc / Clms Page number 176> tick on a wire leading to the next selection stage to allow the successive recording of the class of the line. 27. A telephone system as claimed in claim 6 in which the two relays are placed in the final selector, the attraction of the test relay of this device when the called line is busy serves to put the second relay under the control of the control wire. 28. A telephone system as claimed in claim 7 or 8 in which the lamp lights up as soon as a finder is activated and goes out when the connection has been established through the operator position. 29. A telephone system as claimed in claim 7 in which the common starting wire can be associated with a determined position, by means of a distributor. 30. A telephone system as claimed in claim 8 or 29 in which the common starting wire can be connected directly to the different positions by the actuation of a key in the event that the distributor becomes defective. 31. A telephone system as claimed in claim 7, 8, 29 or 30 in which when the searcher has found the calling line, a pulse emitting device is automatically connected to the position which controls the establishment of the connection. 32. A telephone system as claimed in claim 7 and 31 in which a subsequent and similar manual check by the operator cannot bring about the commissioning of a device for sending the pulses. 33. A telephone system as claimed in claim 31 in which the connection of the device for sending im- <Desc / Clms Page number 177> pulses are carried out automatically when the digits of the desired number have been sent. 34. A telephone system as claimed in claim 31 in which two connection circuits associated with the device for transmitting the pulses are used alternately to associate the device with the position. 35. A telephone system as claimed in claim 31 in which each finder is permanently associated with a selector to form a connection circuit, the pulses necessary to establish the connection are transmitted through the selector, it follows that the finder and the selectors are directly connected in - seems. 36. A telephone system as claimed in claim 9 in which a time device starts a cycle of operations from. when a connection is established, it is used to call back the operator at the end of the cycle, but if the called subscriber answers before the cycle is finished the device in time returns to idle to prevent the callback. 37. A telephony system as claimed in claim 36 in which the operation of the device in time is suspended in the case of outgoing calls established by the operator. 38. A telephone system as claimed in claim 9 in which the operation of the local subscriber's call dial causes the operation of a supervisory signal at the operator position, this signal persists until the operator answers. 39. A telephone system as claimed in claim 9 in which if the call is routed through a trunk circuit to a secondary office the operation of the called subscriber's call dial reverses the direction of the current in <Desc / Clms Page number 178> the junction circuit to cause the operation of the supervision signal. 40. A telephone system as claimed in claim 38 in which for an outgoing call the line of the calling subscriber is extended to the operator position by means of a line circuit which comprises a relay whose circuit closes by the operation of the call dial and which is blocked in a circuit ending in the operator position, this blocking circuit comprises the supervision signal. 41. A telephone system as claimed in claim 9 in which the operation of the call dial together with the actuation of the key serves to trigger the commissioning of a repeater, specific to the subscriber line, which keeps the selection train in the working position after the calling subscriber hung up his receiver. 42. 'A telephone system as claimed in claim 10 in which when the repeater is operating under the control of the called subscriber a signaling device is activated to inform an agent that the selection stream is blocked and that the path followed for the establishment of the connection must be traced. 43. A telephone system as claimed in claim 43 in which the operation of the repeater causes the pull of a relay in the final selector of the selection train, which closes the blocking circuit of the relay which controls the release of the switch and opens the bridge placed on the incoming wires to transmit the blocking to the previous switches. 44. A final selector as claimed in claim 11 in which when the called subscriber hangs up his receiver a relay releases in the final selector, he releases / <Desc / Clms Page number 179> the relay which controls the connection of the final selector to the line of the called subscriber, 45. a final selector as claimed in claim 44 in which the first relay is placed under the control of the supply relay of the subsequently called subscriber the attraction of another relay to cut the sending of the inrush current when the called subscriber answers. 46. A final selector as claimed in claim 12 in which when the conversation circuit has established itself a special tone is applied to the line to indicate to subscribers engaged in an ongoing call that the secrecy of their conversation is not. more guaranteed. 47. a telephone system in principle as described and shown in the attached plans.