BE474772A - - Google Patents

Description

       

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  Telephone network.



   The present invention relates to telephone networks in general, and more particularly to improvements in automatic switching equipment. These improvements are applicable to a network of small exchanges with varied traffic requirements, such as, for example, free access for some subscribers to neighboring exchanges, while other subscribers are charged.



   The traffic requirements mentioned above can arise when subscribers, in an area too small to provide a profitable exchange, are connected to a neighboring exchange; the tariffs in use may require that these transferred subscribers have free access to other neighboring exchanges. If this operating mode is applied to small exchanges, it is not

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 neither convenient nor economical to direct untaxed calls to an operator, or to set apart certain subscriber lines or even to provide separate groups of connection units for paid and untaxed calls.

   Accordingly, one of the general aims of the present invention is to allow any line or group of lines to be easily adapted, to enable it to transmit or receive communications over any or all of its lines. which groups of connection bodies determined, while other subscribers do not have the opportunity to enjoy this advantage.



   A feature of the present invention is the economical arrangement for effecting the control of the junctions according to the classification of the line, extending all the actuation circuits via a common control apparatus, which is not connected. only during the short intervals required for establishing a connection between a branch circuit and a line or junction.



   Another characteristic is the arrangement of the circuits making it possible to release the common connection equipment from the junctions in the event that. a communication is blocked, and is not transmitted within a determined period of time.



   Another purpose is the selection of multiple trunk groups, and PBX (i.e., multi-line) subscriber lines that can be extended via a common access relay, the selection of the trunk groups being dependent. the numbering of the various call numbers with a single digit, and the selection of the PBX subscriber numbers depending on the numbering of several digits.



   Another feature relates to the selection of a trunk group, a group of subscriber lines, individual subscriber lines or individual trunk lines which are extended to the same connector group relays or

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 relay of tens; in which each group or each individual line assigned to it may have different classifications of service.



   Another feature relates to the control of the classification of lines, depending on whether their access is from a one-digit call number or from a multi-digit call number.



   Other features relate to the extension of service classification marks to trunk repeaters located between exchanges, whereby certain designated lines enjoy special privileges which are denied to other lines.



   Other characteristics relate to the adaptation of auxiliary equipment to the usual junction repeaters, to allow sufficient interurban service facilities on the junction circuits between several centers, to allow the use of the network. customary equipment at the central connection, and to control said auxiliary equipment from a single junction access circuit, to allow only designated lines to use these special facilities.



   Another object of the present invention is to provide an improved method for enabling an operator to ignore the busy state of a line, whereby the operator can dial an additional digit after the 'busy state has been observed, instead of cutting the link and dialing a prefix digit in addition to the subscriber's regular number.



   Another feature of the above refinement is that it is easy to restrict the number of digits that the stations affected by service restrictions can dial on the trunk lines joining the exchanges.



  Yet another object of the invention is to use the

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 class of service facilities as a control means for actuating a flickering super-mission signal, as a visual indication of busy status, when calls are requested by the operator on trunks of a class determined service.



     Other characteristics relate to improvements in a distributor apparatus for connection circuits over that described in US Pat. 2,333,039, to provide a more economical method of measuring the length of time that a blocked communication can maintain a connection circuit before it is released to the distributor, and a method of recording the number of times that all circuits baked researchers are busy.



   Other objects of the invention relate to an inexpensive method allowing. an operator to control the equipment responding to dialing in order to remotely control the alarm and battery charging device of the central unit.



   The objects, as well as the characteristics and the improvements mentioned above will become apparent from the following description, which will first be general, then detailed, of the drawings which form part of this patent; other characteristics which are not specially mentioned will also emerge.



   The invention, both as regards its arrangement and mode of operation as well as its aims and advantages, will be better understood by considering the application to a complete telephone network. Accordingly, Figure 1 schematically shows a small central office in a network of four central offices.



  The small central office is shown by the usual diagrams, including Figures 2 to 24, inclusive. The other exchanges are represented in a general way, and can be of the type revealed here,

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 or any known type which reverses the battery when answered to the communication.



   The diagrams, arranged in accordance with the plan shown in FIG. 25, represent an exchange of the well-known "all relay" type, with a capacity of 200 lines. Networks of this general type are disclosed in US Pat. No. 23412 (reissue) and in US Pat. No. 2,333,039, which will be referred to below.



   Figure 2 shows a set of line circuits; one of which is shown in detail.



   Fig. 3 represents a call distributor common to all line circuits.



   Fig. 4 shows the control circuits of the common paging distributor, a relay distributor for preselecting free finder-connector circuits, and two group auxiliary relays for service restrictions.



   Fig. 5 represents the all-relay researcher, in broad outline.



   Figs. 6, 7, 8, 9 and 10 represent the relays of the connector part of the finder-connector circuit.



   Figs. 11, 12, 13, 14 and 15 represent the common junction control and selection relays, which control the connections with the various junction groups.



   Figs. 16, 17 and 18 show the circuits of the repeater 1600.



   Figs 19 and 20 show the circuits of the repeater 1900.



   Freeze them. 21, 22, and 23 represent the circuitry of the dial-back repeater.



   Fig. 24 represents the alarm control and supervision circuits.



   Referring now to fig. 1, the central is re

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 shown schematically by part of the terminal terminals of the researchers and the connector, and their connections to the various line circuits. Only two groups of terminal terminals, such as group 200 and group 210, are shown as being accessible to the finder to extend incoming communications, that is, those from line circuits. Only two groups of terminal terminals are shown below the connector, through which the outgoing connections are made.

   The incoming communications coming from the manual exchange 200 'are transmitted by the trunk line to the line circuit LC 200, which involves the searcher to establish the link with the tenth, or last exit of the group 200. The incoming communications coming from the exchange 16 arrive through repeater 1600 and LC line circuit 205, and are transmitted through the 3rd, 4th and 5th outputs of group 200. Incoming trunk calls from the inter operator position 290 are transmitted. - put through the repeater 201 ', the line circuit LC 201, and the 1st and 2nd. group 200 outputs.

   Other inbound communications from operating position 290 are also transmitted through back-dial repeater 2100, and the first searcher outputs of group 210. LC line circuit 206 is used. by the operator to establish the dial-back connections that can be extended via. the local exchange via the 6th, 7th and 8th group 200 pager outputs. Incoming communications from the suburban automatic exchange are transmitted via repeater 1900, line circuit LC 215, and 5th. exit from group 210.

   Incoming communications from subscriber lines are transmitted through their corresponding line circuits and

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 terminate at the finder's pads, as shown for lines A and B.



   Outgoing communications from the collector outputs to the various trunk groups and trunk groups are established by dialing a single digit call number for trunk groups, while the trunk groups are dialed. - PBX gnes and subscriber lines require 3 digits plus a ring digit.



   Communications to the group of "0" trunks are extended through the Intermediate of the first two outputs of the connector, in the upper group and by the repeater 201 'to the inter panel. 290. Communications to trunk group "7" are extended through the 3rd, 4th and 5th outputs of the connector, in the upper group and through repeater 1600 to central 16. Communications to The junction group "9" are extended through the 6th, 7th and 8th outputs of the upper group of the connector, and by the repeater 2100-, up to the operator position 290.

   Communications - to trunk group "8" are extended through the 4th and 5th outputs of the lower connector group, and through repeater 1900, - to the suburban automatic exchange. The communications to group P B X are extended through the Ie, 2nd, 3rd and 6th outputs of the lower group of the connector.



  Communications to the local subscriber groups are extended as shown by the 8th, 9th and 10th outputs of the lower group of the connector. An alarm and supervision circuit A L C is represented as terminating at the IOth output of the upper group: it allows an attendant to dial in the local control unit and to test for various troubles in the event of an alarm. It should be noted that this arrangement is only schematic, and that other junctions where lines can be grouped other than shown, the figures having been drawn up so as to describe the number of circuits shown to fully describe the 'invention.

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  In all the figures, the relays not specially marked are instantaneous operating relays; relays which are normally actuated are shown in the pulled position; the relays shown with a black rectangle at the end of the winding are delayed on release; the relays shown with a cross at the end of the winding are delayed on switching on, and the relays shown with a double frame are delayed on both switching on and off. A brief description will now be given of the equipment shown in FIGS. 2 to 24 inclusive.

   It refers to groups of hundreds which correspond to a subgroup of 100 lines from the exchange to groups of tens, which correspond to subgroups of 10 lines, and to units which correspond to individual lines. of the subgroup.



   Fig. 2 shows the various line terminations for subscriber lines and junctions.



   Only a certain number of line circuits have been shown, sufficient to include the restrictive service facilities described in this patent. We do not cohsider the different species of subscriber lines that may arise; it is implied that these can be shared lines serving up to 20 extensions each, individual lines, or PBX lines (that is, lines for subscribers additional extensions). mentaries). The numbers on each line correspond to the outputs of the researcher contact bank. All line circuits are similar to circuit 216, and have characteristics similar to those described by US patent no. 2,333,039 mentioned above.

   It is understood that where the junctions end at repeaters, the connector outputs are connected to repeaters, as shown in the figure, instead of to the line circuit, such as 216.



   Line circuit 206 is not shown in detail, being

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 given that it was only used for the transmission of communications on the same shared line for trunk group n 9. It is broadly similar to circuit 216, except that the conductor corresponding to conductor 285 is ends at contact 315 instead of 317, and that the outputs from the finder contact bank end at outputs 211 instead of 216.



   The manual tables 200 'and 290 are of the usual well-known type operating with automatic exchanges, and requiring no further description.



   Likewise, repeater 201 'is of any well known type of repeater for automatic central offices and direct traffic, such as repeater 7 of US Patent No. 2,333,039 mentioned above. The repeater 1600 is represented here by figs. 16, 17 and 18; the repeater 1900 is shown in Figures 19 and 20, and the repeater 2100, in Figures 21, 22 and 23.



   The call distributor of FIG. 3 is a well known apparatus for controlling the extension of a finder to a calling line, and preventing any other calling line from being connected until the finder is connected to the line.



   Fig. 3, in conjunction with fig. 4, has characteristics similar to those of the aforementioned US patent.



  It is again understood that an represents only the group and unit relays necessary for the description of the operation, and that a group relay 300 etc ... is required for each group of 10 lines, or a total of 20 for 200 lines. The complete panel requires 10 relays of 320 units etc ...



   Fig. 4 represents the researcher circuit, the distributor and the common control equipment. The distribution part consists of one relay per searcher-connector circuit, of which

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 two relays 460 and 470 as well as the recovery relay 440 are shown. This distributor is of the well-known cyclic type, in order to assign in advance the order in which the free connection circuits are to be used by transmitting successive communications. The other part comprises the recording and control equipment. Fig. 4 differs from previous devices in that a recorder 484 for the total occupation of the junctions is provided, controlled by relays 415, and that the timing apparatus is simplified by the control of the duration by a common timer 480.

   It is understood that the timer 480 is normally incorporated into the timer 760 '. Fig. 5 shows only a part of the complete connection circuit. It is understood that one group connection relay, such as 500, is required for each group of 10 lines, making a total of 20 similar relays for all 200 lines. Only two of the five unit relays and the unit switching relay 540 are shown. This apparatus is similar to that described in the aforementioned United States patent except that, for ease of description, special service marks are based on lines, mine is based on groups.



   Fig. 4 represents the auxiliary relays of groups of lines subject to restrictions. It is understood that such a relay is provided for each group of 10 lines comprising lines having special service characteristics.



  Two similar relays 420 and 480 are shown; they are to be considered as the auxiliary relays of the tens 200 and 310 relay groups. Such relays intervene only during the period when a seeker is moved to a calling line, and extend a special service mark to a restriction relay determined 930, 940 or 950 of Figure 9, or to the group restriction relays shown in the connector.

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   The connector group restriction relays are shown in fig. 9, it is understood that a relay or a combination of relays is required for each set of restricted lines; three of these relays (930, 940, and 950) are shown, which make it possible to obtain four classes of restricted lines, with the common blocking relay 960. This only intervenes when a group number of connectors is called by a line that is not allowed there. The timing pulse generator 760 ', the call breaker 761, the call generator and the signal generator are well known, and are shown only schematically. It is understood that these devices can be either controlled by relays or controlled by cams driven by a motor.



   Figs 6, 7, 8, 9 and 10 show an all relay connector for 200 lines, comprising 20 tens of tens (or group relays), 5 unit relays and one unit switching relay, as well as other control relays. The general characteristics of this connector are similar to those described in the aforementioned US patents, and are well known. Briefly described, it is of the 200: line type, with a maximum of 20 sets per line.

   Four digits are required to call local extensions: the first digit determines the hundreds group and the extension ring group; the second digit determines the tens group from the selected hundreds group; the third digit determines the individual line (units) of the selected tens group; the fourth digit determines the particular ringtone of the selected group. The trunk groups are selected by a single digit number.

   Only two of the tens relays (or grouping of the connector have been shown: relays 1030 and 1040; similarly, we have not shown in Figure 10, to simplify

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 the description of the diagrams, that two of the alunite relays of the connector: relays 1010 and 1020; the rela.is 1000 is the units switching relay. Each small group of junctions can be considered as a subgroup of the tens groups. Several similar sub-groups, with subscriber lines, can be assigned among the same group of tens, provided that the total number of junctions and lines they contain is not greater than 10.



   The unit relays 1010 and 1020 mentioned above are controlled directly by the counting relays in fig.



  8, in response to the 3rd numbered digit, or are energized by the junction selector relays, such as those shown in figs. 11, 14 and 15, via the junction access relays of figs. 12 and 13.



   The C 200 line outputs are designed to access the remote supervision equipment (figs 24); they are the same as any other subscriber line, except that an additional conductor is provided, through which additional dial pulses are repeated.



     In addition to restriction relays 930,940 and 950, it is shown by relays 625 and 644 how an inter-urban line of a certain classification enjoys the combined facilities controlled by the two relays mentioned above, while a line interurban service of another classification only enjoys some of these facilities, such as those controlled by relay 644.



   The connections of the junctions with the different groups of junctions are made by means of common selector devices, which select a free junction in their respective groups by marking a corresponding conductor using a marking potential, to control the operation of the relay units of the connector when this group of junctions is called The common junction selection device

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 includes group access relays, trunk group relays and trunk selector relays. Fig. 12 shows a part of the group access relays and the trunk group relays, which is provided to allow trunk connections with groups 0, 9, 7 and P B X.

   A relay such as relay 1200 and 1210 is provided for each connector of the group access relay; relays are incorporated into a chain circuit so that only one of these relays can be energized at a time, in order to prevent faulty connections.



  The group access relays established. ent the connections between the corresponding caller connector and the junction group relay contacts. The particular junction group relay corresponding to the called junction group is actuated, to extend the connection of the connector to the junction selector relay group, as shown in fig. 14, in this way to connect the marked conductor, corresponding to a free junction of this group, to the units conductor of the connector, to actuate the corresponding units relay of the connector. A trunk group relay, such as group 0 relay 1250, is provided for each separate group. Such junction group relays are common to all connectors.

   The junction selector relays in fig. 14 individually belong to the group of junctions 7, and include a relay, such as relay 1440, which is normally energized when the repeater is free.



  A chain of relays 1410, 1430 and 1450 are provided, to preselect the free junctions successively, by earthing the conductors corresponding to the relays of the connector units. The relay 1460 is a recovery relay, used to restore the connection. relay chain, after the last junction is used, so as to successively preselect new free junctions.



  Relay 1470 is a delayed release relay, which drops back to mark the occupation of this group of junctions, when all

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 junctions are used. The relays 1220 and 1230 in fig. 30 are controlled by relays 1200, 1210, etc ... to introduce a slight delay in the reestablishment of the actuation circuits of these latter relays, so that they cannot be energized prematurely before the relays select. - junctions have worked) to release the marking of a junction that has just been occupied for a communication, and to mark the next free junction in the group.

   Eject relay 1240 is a delayed trip relay which is normally kept pulled during the selection of the junctions, 2 unless, for one reason or another, a junction is not selected during the time. of the time delay of said relay in which case the relay drops out, and causes the preselection of the next free junction, while the calling subscriber receives the busy signal.



   The junction selector relays of groups 0 and 9, shown in fig 11, are similar to those of group 7, shown in fig 14. Figure 11 also shows a group of group congestion relays, which allow the group 0 communications to use group 9, in case of congestion, when group 0 is called and all the junctions of this group are busy.



   Figure 13 shows the group access relays and the trunk group selector relays? 8.



  This group of trunks normally carries very heavy traffic and a separate group of access relays is provided to allow. a connector to call this group of trunks even when another connector is busy establishing another trunk communication through the group access relays of figure 12. The group access relays of figure 13 are similar to those of figure 12, and the junction selector relays of group 8 are similar to those of group

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   pe, 7, shown in FIG. 14. A relay: separate, such as the relay. 1300, is provided for each connector and since these relays are only intended for a group of junctions, no relay group of junctions, tels only the relays. I250 to 1280, are not needed.



   Fig. 15 shows the junction selector relays for the group of junctions P B X, comprising the relays 1510 to 1540, which are energized when the corresponding junctions are occupied. The first junction P B X is represented as being occupied, the relay 1510 having dropped out, to preselect and mark the first; junction P B X to contact I5I2.



   Figs. 16, 17 and 18 represent the relays and circuits: of the repeater 1600, including the. conductors 207, 208 and 277 terminate at the outputs of the connector, as shown in fig. 10; the conductors 1443 and 1444 extend to the junction selector relays of the. fig. 14 and the connecting line conductors: (fig. 18) extend to the remote center 16, as shown in fig I.



   Figs. 19 and 20 show the relays and circuits of the repeater 1900, of which the conductors 217, 218 and 295 extend to the line circuit 216, the conductors. 1074, 1075 and 1076 extend to the outputs of the connector of fig. 10, conductors 1379, 1399 and 1999 extend to the trunking selector relays of trunking group No. 8 (fig. 13) and conductors 2099 and 2098 extend to the automatic sub-office, as indicated. ¯ qué in fig. I.



   Figs. 21, 22 and 23 show the relays and circuits of the dial-back pulse repeater, the conductors 1092, 1093 and I094 of which terminate at the outputs of the connector of fig. 10, the conductors 2112 and 2113 terminate at the junction selector relays of group 9 of fig. 11,

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 conductors 275, 276 and 2283 terminate at line circuit 206, to make the numbering connections., in return, conductors 212 and 213 terminate at line circuit 211, to close incoming communications on the dial line. junction, and conductors 2398 and 2397 extend to switchboard 290.

   This repeater is quite similar to the dial back repeater 61 described by US Patent No. 2,340.



  554, except for circuit modifications which improve both operating characteristics and construction economy.



   Fig. 24 shows the alarm and supervision circuits, which are accessible via conductors 1095 and 1098 from the connectors, to allow an operator to link up with them, and to check. the various cases of abnormal operation or alarm signals, such as the fuse alarm; insufficient voltage alarm, generator transfer and other cases, described in more detail in the following by numbering a digit.
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  Local comrciunicatipns.



  Having briefly described the purpose of the equipment shown in the figures, the operation will be best understood by a description based on reestablishing local communication, then describing the operation of each special feature.



  For this purpose, assume that station "B" on line L 216 calls station "A" on line L 270, dialing digit 270 as well as ringing digit "I".



   Communication is initiated by station "B" when it picks up its handset, which closes an actuation circuit for line relay 240, through the calling loop, comprising contacts 251 and 252. Relay 240, through its. contacts 244 and 245, prepares a line marking circuit, by energizing the tens group relay 310 and the unit relay 340. The line is made busy for outgoing communications by opening the

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 circuit from relays 250 and 260 to contact 241, and for incoming communications by grounding conductor 259 to contact 242.

   The excitation circuit of the relay 310 comprises: the earth, the: contacts 244 and 262, the conductor 283, the coil of the relay 310, the contacts 312. and 361, the; contacts in series 314 and 304, conductor 499, contact 432, resistor 485 and battery -. Contact 313: closes first, and keeps relay 310 energized after closing the primary excitation circuit. to be described, and the primary excitation circuit for all, group relays 300, 310 are open at contacts 312 and 314, respectively.

   The primary excitation circuit of relay 340 consists of: earth, contacts 245 and 263, conductor 285, contact 317, coil of relay 340, contacts 342 and 362, chain of contacts 354-324 , resistor 368 and the battery. Contact 343 is the first to close, keeping relay 340 energized after the primary 'energizing circuit described above' (of relay 340) and. the primary circuit for excitation of:

   all unit relays 320-350 are open., respectively at contacts 342 and 344. Relay 360 is energized at contact 345, reopening the primary actuation circuit of the group relays at contact 361 and that of the relays units at contact 362. Relay 360 prepares at contact 363 a timing circuit comprising relays 400, 410 and 430.



  The operation of relays 400-430, as well as that of relays 440-470 will be explained in a special chapter, dealing with the distributor of connection circuits. For the moment it suffices to understand that the diagram represented. refers to the last circuit of. connection of a group representing the relay. 410 energized and 460 de-energized, the conductor 394 being connected through the contacts. closed 411, 461 and 472, conductor 493 and the. connection relays 550 and 560. Relays 550 and 660 are energized

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 in multiple with relay 360, according to the circuit described above from earth to contact 345.

   Relay 550, at contacts 551-555, extends conductors 397, 398, 399, 453 and 454 respectively to the subgroup or unit switch relay 540, to unit relays 530 and 520 and to group relays 510 and 500.



   The group relays 500, 510 can be controlled either directly by the corresponding group relays 300, 310 of the distributor, when the group does not have restricted lines, or by the auxiliary relays of groups 420, 480, when '' these are restricted traffic lines. Unit relays 520, 530 can be controlled by unit relays 320, 330 from the distributor at contacts 326 and 336, and can also be controlled by the relay of distributor units 340 and 350 to contacts 347 and 357, respectively. Relays 340 and 350, representing the unit digits 6 and 0, also drive the subgroup relay 540 at contacts 346 and 356.

   The operation of the restricted traffic device comprising contacts 321 to 351 inclusive as well as the contacts controlled by relays 420 and 480 will be explained in a following paragraph entitled "Reduced traffic".



   Specifically, the relays 510, 520 and 540 are energized when the relays 310 and 340 are energized as has just been described. Relay 480 is energized, depending on the ground, contact 311 and conductor 395. Relay 480 transmits to contact 481, a ground to conductor 453, and connects the flow of relay 510 to the. battery. Relay 510 closes contacts for a group of 10 lines, comprising contacts 514, 515 and 516, to extend conductors 295, 296 and 297 respectively, to contacts 524, 525 and 526. Relay 520 is energized by the grounded contact 347, the conductor 399 and the contact 553.

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  Contacts 524, 525 and 526 connect the extended conductors 295, 296 and 297 with contacts 542, 544 and 546, respectively. The relay 540 is actuated by the. earth at contact 346, via conductor 397 and contact 55I. Conductors 295, 296 and 297 are again extended at contacts 542, 544 and 546 to conductors 508, 509 and. 594. As described previously, relay 560 is energized in multiple with relay 550.

   An excitation circuit is closed at contact 561 for line relay 610, depending on the earth, the top input of relay 610, les. contacts 621 and 601 ', the conductor 508, the contact 561, la. resistor 569, conductor 509, contacts 602 'and 623 and the lower coil of relay 610 to the battery ,. Relay 610, at contact 611, transmits earth to contact 663, to energize relay 630. Relay 630, at contact 631, remains earthed through resistor 615, to remain attracted. - until contact 611 is open. At contact 633, relay 630 transmits an earth to contact 681, to energize relay 640. Contact 642 energizes relay 660. Relay 660 connects to contact 664, a ground to conductor 593.

   The excited relays 510, 520 and 540 are maintained respectively by the contacts 517, 527 and 547 to the maintaining conductor 593. The relay 660 which is attracted, transmits the earth '- by its contact 661y to the contactor 642, - to conductor 594, which energizes relays 250 and 260 in series by conductor 297, contacts 516, 526 and 546 and conductor 594. Relay 250 opens to contacts 251 and 252 le. Line 240 relay circuit. 240 relay drops out; it opens contacts 242, 244 and 245, and relays 310 and 340 drop out. Contact 345 opens de-energizing relays 360, 550 and 560.

   After a slight delay, the relay 360 drops out, and the common equipment of fig.3 returns to the rest position, ready to. transmit a new communication. The re-

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 The 510, 520, 540, 250 and 260 remain attracted to earth at conductors 593 and 594.



  Distributor of connection circuits.



  Before continuing the description of connector relays, let's go. describe the operation of the branch circuit distributor.



     Diaprés the. As described above, relay 660 was actuated after relay 560 had operated. Relay 660 opens contact 669, and, after relay 560 is de-energized, contact 562 is opened. This combination of de-energized relay 560 and energized relay 660 opens the closed circuit between conductors 495 and 494, and relay 470 drops.

   Relay 470, at contact 477 completes the chain circuit through contact 467 to relay 440. An incomplete circuit is prepared at contact 475, to re-energize relay 470. It is understood that this occupied connection circuit has the relay 660 energized; therefore, relay 470 cannot be re-energized, since its actuation circuit is open at contact 669.The same condition exists for all other occupied connection circuits and none of the corresponding relays such as 460 and 470 cannot be re-energized if the connecting circuit is busy.



   For ease of explanation, it will be assumed that the connection circuit associated with relay 470 is free. The relay 440 is energized by the chain of contacts 467-477 and transmits the earth of the contact 442 to the contacts 465, 475. All the corresponding relays associated with a free connection circuit are energized according to a circuit similar to the following, concerning the relay 470: earth, contacts 442 and 475, conductor 495, contacts 684 and 669 ', conductor 494, relay winding 470, and battery. Relay 470 prepares at contact 472 an excitation circuit for connection relays 550, 560. Previous relays, such as 460, are also actuated, and, in a similar manner,

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 conductor 394 is extended to the next connection circuit.

   After a link is extended by a previous connection circuit, the corresponding relays 460 etc ... of the distributor are de-energized in the same way as for relay 470.



   Contacts such as 461 are closed, and conductor 394 is extended to the next connection circuit by contacts such as 472, up to conductor 493.



   If all connection circuits are busy, relays 460-470 cannot operate again, and relay, 440 remains in the energized position. The circuit of the delayed tripping relay 415 remains open at contact 44I. Relay 416 drops out, after a slight delay, and activates full occupancy recorder 484 through contact 416. In addition, chain contacts 461, 471 extend conductor 394 to relay 450.



  If communication is requested during the period of full occupancy, the earth located at contact 345 or similar contacts actuates relays 450 and 360. A holding multiple circuit for relay 450 is closed by earth at contacts 444 and 452.



  Relay 450 opens at contact 451 the timing circuit extending to the lower coil of relay 400. When a connection circuit becomes free, the associated relay such as 460 or 470 is actuated again, as described above. previously described, and the relays 440, 450 return to the rest position.



   In the event that a connection circuit chosen by the distributor is not extended to a calling line after a determined time, it is released, and the call is transmitted to the following connection circuit as follows: relays 310, 340 and 410 as well as 360, 550 and 560 are actuated as described previously. Relay 360, at contact 363 extends conductor 497 coming from timer 480, to conductor 491 and to the lower coil of relay 400. An earth pulse produced by timer 480 on conductor 497 energizes relay 400,

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 which maintains itself to the earth by the contact 345. The relay 400 extends, at the contact 402, the second impulse conductor of the timer up to the relay 410. The file 480 is well known and should not be represented in detail.

   It suffices to know that it delivers a second earth pulse, approximately 3 seconds after having delivered one to the conductor 497. This time interval is of a sufficient duration to normally allow the extension of a connection circuit. to the calling line and release of relays 310 and 340. Suppose the connection circuit is not extended and relay 410 is actuated after the specified time delay. The battery is extended to contact 412 from resistor 485, through contacts 431, 463 and 474, lead 495, contact 562 and lead 494, relay 470 and the battery. This connection to the battery bypasses relay 470, which drops to assign a new connection circuit, as described previously.

   At contact 413, relay 410 energizes the delayed closing relay 430. The delay of the latter is sufficient to activate the shunt which releases the relay 470 before the contact 431 is opened. The contact 432 disconnects the battery. traversing resistor 485, so that any attracted tens guard relay, such as relay 310, drops out to prevent a faulty line circuit from holding the distributor and successively taking them into service. free connection circuits.



   Contact 317 opens, and relay 340 drops out. Contact 345 opens, and relays 360 and 400 drop, to open the circuits of relays 410 and 430. After contacts 314, 312 and 361 close, relays 310 and 340 are energized again by the relay. 240, and communication is established on the next connection circuit. Obviously, any other call with a privileged assignment will be extended before the cut call is extended a second time.

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   CONNECTOR.



  In the preceding description, a communication was established from the line, calling B ,, via the circuit of the finder (fig.5), to: conductors 508, 509, 593 and 594 of the connector, (fig.6).



  The relay 610 was energized first by the contact 561, and, thereafter. release of relay 560, having been. explained, was held in the attracted position via the calling loop of station B. In addition, relays 630, 640 and 660 were energized at contacts 611, 633 and 642, respectively, preparing the additional control circuits.



   The operation of the connector will now be described, when the calling subscriber forms the call number of the called station.
The circuit comes complete. line conductors 508 and 509 is successively opened and closed by the dial disc contacts of calling station A, and relay 610 follows these pulses, opening and closing its. contacted 611, 612 and 613.



  Relay 640, because of its tripping delay, keeps relay 660 energized during successive numbering pulses. The relay 630 drops out, after the opening of the contact 611, and transmits an earth, to the contact 634, through the contacts 606 and 666, the conductor 693, the contacts 714 and 775, the conductor 728, contacts them 811, 821 and 831, the coil of the relay CI and the. drums. Relay 970, connected to conductor 728 in multiple with relay CI, is energized according to the circuit described above. The delayed tripping relay 970 does not fall back between successive pulses, and the control circuits of the CI to CO relay contacts are temporarily disabled at contacts 971-973.

   The relay CI prepares on contact: 871, an excitation circuit for relay 830, in series with relay CI, after the earth- is disconnected from conductor 728 at contact 634. The above functions are applied. during the opening period produce the first dialing pulse from 1- * calling subscriber. The contact of the

  <Desc / Clms Page number 24>

 dialing closes again, and relay 610 is re-energized. The energization of relay 610 is facilitated by a circuit comprising resistor 614, contacts 641, 613 and 681, and earth. Earth through resistor 614 only re-energizes link 610 when the loop between conductors 508 and 509 is closed by disk contact.

   Relay 650 is energized through contacts 643 and 632. Relay 630 is re-energized according to earth at contact 651, contact 611 and battery. Relay 610 closes, at contact 612, a multiple circuit for holding relay 640, by earth at contact 681. At contact 632, relay 630 de-energizes relay 650, and opens at contact 634 the pulse circuit of the relay CI described previously. The IC relay remains energized by contact 871, relay winding 830, contact 823, conductor 708, contact 774, conductor 692, contacts 603, 691 and 662, and earth.

   Before relay 630 operated again relay 830 was shunted by the earth to conductor 728 by contact 634. Relay 830 is now energized in series with the coil of relay IC. The first circuit described for relay CI is further opened at contact 831, and an excitation circuit for relay C2 is prepared at contacts 832 and 876. It is useful to note here that the purpose of the re- Theis 650 is to ensure the CI relay an effective pulse through contact 634. Normally, relay 630 cannot be re-activated, even if line relay 610 is energized, before relay 650 closes contact 651. .

   Relay 650 is drawn slower than relay CI; therefore, it is obvious that if the relay 610 were to be energized prematurely, the re-energizing circuit of the relay 630 would not intervene, as long as an earth pulse of sufficient duration to cause the operation of the relay. CI relay has been transmitted to it. Analogously to that described for relays CI and 830, relays C2 and 820 are

  <Desc / Clms Page number 25>

 Excited in response to the 2nd. pulse .. Contact 823 opens, and the. relay; CI and 830 fall back. The time-delayed tripping relay '970, remains in the attracted position for the duration. successive pulses) and prevent the counter relays from actually energizing the transfer circuits for the duration of this period.



   The first digit of the calling number is 2. During the interval between digits, relays 610, 630, 640 and 660 are energized; relay 970 drops out and the following operations take place: relay 860 is energized depending on the battery, its winding, the GS conductor 2, contact 878, conductor 3 of cable 968, contacts 912, 901 and 972, the conductor 729, contact 824, conductor 655, contact 662 and earth. Relay 860, at contact 862, closes a multiplied hold circuit, in series with relay 910, through earth to conductor 698. The earth circuit which actuates relay 860 prevents relay 910 from operating at. this moment.

   Relay 860 energizes relay 690, at contact 861, depending on: battery, lower winding 691, conductor 706, contact 907, 917, conductor 908, contact 861, conductor 698, contact 667 and Earth.



  Relay 690 at contact 691, opens the earth holding circuit for relays 820 and C2. Relays 820 and C2 drop, removing the earth: bypassing relay 910 to contacts 824 and 878.



  Relay 910 is now energized in series with relay 860, by contact 862, conductor 909, coil of relay 910, conductor 698, contact 667, and earth. Relay 910 transfers to the contacts; 9I6 and 917 the excitation circuits of relay 690, from conductor 908 to conductor 98), and relay 690 drops out.



   The connector is then ready to receive the. 2nd. number 7.



  The operation during the first two pulses is the same as that described for the. first digit. After the second pulse earth is opened again at conductor 728, through contact 634, and relay 820 is pulled. Relay 820 opens,

  <Desc / Clms Page number 26>

 at contact 823, the relay circuit 830 and CI. Relays C2 and 820 prepare the drive circuit from relay C3 to contacts 879 and 822. Relay C3, and then relay 810, are energized by 3rd. pulse, which prepares a drive circuit for relay C4 at contacts 882 and 812, and de-energizes relays 820 and C2 at contact 813. On the next pulse, relay C4, and then relay 830, are all energized two and relays C3 and 810 drop out.

   Similarly, successive pulses energize the corresponding relays, and after 7 pulses, relays C7 and 830 are energized. The time delay relays 640 and 970, as well as the relay 660, remain energized for the duration of the dialing. Relay 970 falls back into the gap between two digits. Contacts 971, 972 and 973 are closed, extending the earth to conductor 655, contact 834, conductor 729, contacts 972, 973, 903 and 915, conductor 4 of cable 968, contact 897 of relay C7, conductor 70 of cable 826, contact 864, conductor 964, contact 953, conductor 981, relay coil 1030 and the battery.

   Relay 1030 is drawn, and prepares for contact 1034 its own maintenance circuit, in series with relay 900. Relay 900 is shunted by earth initially energizing relay 1030, until the circuit of the relay. conductor 981 is open at contact 834. Relay 690 is energized according to a circuit comprising earth at contact 667, conductor 698, contact 1033, conductor 982, contact 916, contact 907, conductor 706, winding relay 690 and the battery. At contact 691, relay 690 de-energizes relays 830 and C7, opening contacts 834 and 897, which disconnect the earth of the primary actuating circuit of relay 1030. Relay 900 is energized in series with relay 1030.



  At contact 906, a circuit is prepared according to which relay 1000 is energized, in the event that the next digit is greater than 5.

  <Desc / Clms Page number 27>

 



  At contact 907, relay 900 opens the circuit of relay 690, and transfers to contacts 904 and 903 the conductor 729 of conductor 4 to conductor 6 of cable 968. At contact 902, conductor 729 is extended to conductor 7 of cable 968. Relay 690 drops out, and prepares at contact 691 a circuit enabling relays 810-830 to be energized at the next digit.



   The next digit, 0, is numbered in a similar fashion.



  Relays 610 and 630 following the pulses, and contact 634 opens and closes 10 times. The counter relays C 1 to C 6, as well as the relays 810-830 are energized during each pulse, as explained previously. Similarly, relay 970 remains attracted during the pulses. After the 10th pulse, the CO and 830 relays are energized, and the 970 relay drops out, energizing the 1020 relay according to the earth conductor 729, the contact 972, the conductor 7 of the cable 968, through the intermediary of the contacts 902, 92le 818, conductor 966, relay winding 1020 and battery.

   At the sixth pulse, relay C 6 energizes relay 1000, depending on the earth to conductor 655, contact 893, conductor 1 of cable 968, contacts 906 and 927, conductor 983, relay 1000 and the battery. On contact 1007, relay 1000 remains earthed, at conductor 698.



  At contacts 1002, 1004 and 1006, conductors 637, 652 and 659 are extended to the contacts of relays of units 1010 and 1020 which correspond to the lines that end with the digits 6 to 0.



  At contact 1029, a holding circuit is prepared for relay 1020, in series with relay 920. The battery for energizing relay 920 is shunted by earth to conductor 966, to coil 1020. Relay 690 is energized. to contact 1028 according to the earth to contact 698, contact 1028, conductor 986, contacts 918 and 928, conductor 706 and the battery to coil 690. At contact 691, conductor 708 is disconnected from earth and the relays CO and 830 drop out, opening contacts 834 and 818.

  <Desc / Clms Page number 28>

 



  The relay 920 is then energized, in series with the relay 1020. The rela.is 920 opens at contact 927 the excitation circuit of relay 1000, and prepares at contact 923 a circuit according to which relay 710 is energized after dialing the number. next digit. Relay 690 is de-energized at contact 928, and the counter relays are again ready to receive the next series of pulses.



   It is assumed that the called line is free; the battery is extended from the CO relay of the line circuit 210 by the conductor 1083, the contacts 1059, 1027, 1000, to the conductor 659. At the contact 925, the relay 920 expands the described test circuit above through 738 and contact 776, to the top coil of the relay, 780, which is energized by ground at conductor 696, through contacts 668 and 607. Relay 780 turns on. maintains at the. earth to conductor 698, by contact 786; the excitation winding of relay 780 is shunted by contact 785. Relay 780 prepares at 781 and 782 a circuit between relay 700 and the station called, by line conductors (C 270) 1081, 1082.

   The above circuit is the transmission circuit when a communication is established, but it is used in this case to establish supervision, in case a station on the called line tries to obtain a communication before the last one. digit is numbered.



   The calling subscriber dials the last digit 1. Relays 610 and 630 answer, and relay 630 again extends, to contact 634, a momentary earth, which energizes multiple relays C 1 and 970. Relay C 1 maintains contact 871, in series with the winding of relay 830. Relay 630 drops out, opens contact 634 and disconnects the earth of impulse conductor 728.



  Relay 830, previously bypassed, is now energized. On contact 872, relay C 1 extends conductor R 1 from the call breaker to driver 719. Relay 970 drops out, and the relay

  <Desc / Clms Page number 29>

 710 is excited, by the earth of conductor 955, at contact 662 by contact 834, conductor 729, contacts 972 and 973, 904 and 923, conductor 736, contact 716, the coil of relay 710 and battery. The relay 710 is attracted and holds on to the contact 717 grounded to the conductor. 655; it opens the pulse circuit on contact 714. At contact 713, a circuit is prepared to energize relay 730.

   At the start of each call phase of the breaker 761 ′, a battery pulse is momentarily connected to the conductor P U-1, to energize the pick-up relay 730, by means of the contact 841, of the conductor 744, contacts 734 and 788, the top winding of relay 730, contacts 704 and 713, conductor 729, contact 834, and conductor 655, which is grounded at contact 662. Relay 730 is energized and energized. maintains by contact 735 the conductor 718, the contact 689 and the conductor 719, to the battery normally closed at the switch 761 '. At contacts 731 and 732, relay 730 extends the call control circuits 745 and 746 to ringing relays 750 and 760, only relay 750 intervening when the call digit is 1.

   Since the digit 2 has been numbered as the first digit, relay 840 is not energized, - and relay 750 alone responds to earth pulses 'from breaker 761'. The relay circuit 750 comprises: the battery, the relay 750, the contacts 731 and? II, the conductor 745, the contact 872, the conductor R 1, and the ground pulses of the breaker 761 '. The relay 750 is energized in response to the described earth pulses emitted on the conductor R 1; it closes on contact 755 the call circuit on conductor 1082 of the called line, according to the call generator GEN, the winding of the call cut-off relay 740, the contacts 755, 764 and 782, the conductor 652, contacts 1004, 1026 and 1058 and conductor 1082 to the called station.

   At contact 753, relay 750 connects earth to the other conductor of

  <Desc / Clms Page number 30>

 line 1081, as inrush current return circuit, in the event of a call on both wires, and also to actuate the call cut-off relay 740 when the called subscriber answers. This circuit includes the ground contact 753, 762 and 781, the conductor 637, the contacts 1002, 1025 and 1057, the conductor 1081 and the called line. The inrush current is alternating current, and has a DC component from the battery, to energize the call cutoff relay 740, when the called subscriber answers. The relay 740 is energized through the line circuits indicated above when the called subscriber answers.

   Relay 740 at contact 741 energizes relay 690, through conductor 706, from ground to conductor 729 previously described. Contact '691 disconnects the earth of conductors 692 and 708, and relays 830 and Cl drop. On contact 872, conductor R 1 of the call breaker is disconnected from relay 750.



  On contact 750, earth is disconnected from conductor 729, and relay 730 drops out, again opening the circuit of relay 750.



   Let us return to the previous description, in which the inrush current is connected to the line drawn by the energization of relay 750. At contact 756, relay 720 is energized at this moment :, Relay 720 opens at contacts 721 and 723 the transmission circuit of the called line. At contacts 722 and 724, earth and battery, via resistor 725, are connected to conductors 637 and 652. Relay 720 is delayed on tripping, and remains momentarily energized, after relay 750 drops out. The earth and the battery are therefore connected to the called line, to eliminate any foreign potentials which remain after the application of the inrush current, before the line is extended to the relay 700.



   When the relay 720 drops, the called line is extended to the relay 700, by the conductors 1081 and 1082, the contacts 1057, 1058; 1025 and 1026 :, 1002 and 1004, conductors 637 and 652,

  <Desc / Clms Page number 31>

 contacts 781, and 782, 762 and 764, 752 and 754, 721 and 723, 794 and 796, at the upper and lower windings of relay 700.



  The relay 700 is energized according to the line of the answering station, and energizes at contact 701, by the conductor 653, the relay 620. The relay 620 reverses the current on the conductors of the calling line for monitoring purposes. The relay 700 also actuates the relay 676, at the contact 702, via the conductor 655, for a purpose which will be described later, when describing the measurement of the duration of the communications.



   After the conversation, when the called subscriber hangs up his receiver, relay 700 drops off and releases relay 620 at contact 701. When the calling subscriber hangs up his receiver, line relay 610 drops out, and opens on contact. 612 the circuit of relay 640, which drops out after a brief interval. At contact 642, relay 640 opens the circuit of relay 660, and disconnects the earth of conductor 594, to release cut-off relay 250 and relay 260 from the line circuit. At contact 664, relay 660 disconnects the earth of conductor 593, to release the relays of groups and units actuated by the finder. At contact 6.63, relay 660 disconnects the earth of conductor 655, to release relays 710 and 680.

   At contact 667, relay 660 disconnects the earth of conductor 698, to release the remaining relays from the connector, such as relays 786, 900, 910, 920, 940, 1000, 1020 and 1030. The finder-connector connection circuit is then released and can be used for subsequent communications.



  Calling subscribers on a shared line.
The selection of different call codes is a well known operation, which will only be described here very briefly. It is

  <Desc / Clms Page number 32>

 evident from the previous description that any of the 10 conductors R 1 to R 0 can be selected by numbering the digits 1-0 as the last digit, to energize one of the relays - counters C 1 to C 0. In an analogous way ,. the driver selected from the call breaker is extended either to relay 750 or to relay 760 depending on the numbered number. Relay 750 will hear if the ringing digit is odd; relay 760 intervenes if it is even.

   When relay 750 trips, the coded inrush current is extended through conductor 652 to conductor 1082, and relay 760 connects the inrush current to conductors 637 and 1081. A total of 10 codes is therefore available to call up to ten extensions of a line. This number is further doubled by providing the conductors R 1 to R 0 for two codes each. The breaker 761 producing this type of code is well known, and therefore, is not shown in detail. It is sufficient to know that the second group of ringing codes has a call pulse, which precedes the first group of codes. Obviously, the prefix signal mentioned above is only effective when relay 730 is energized.

   Therefore, the switch is arranged so as to close the battery on the conductor P U-1 only between the first and the second signal of a code. Likewise, the driver's battery P U-2 precedes all call pulses. Obviously, relay 840 controls the connection of the P U-1 or P U-2 conductors to relay 730, to determine whether code group 1 or code group 2 is being used. Relay 840 is energized in combination with relay 860 if the first numbered digit is a 3, and in combination with relay 850 if :, digit 5 is numbered. When the. first digit is 2 or 4, relay 840 is not energized. As a result, the first group of codes occurs when the first digit is 2 or 4, and the second

  <Desc / Clms Page number 33>

 group when it is 3 or 5.



   As previously described, relay 730 is kept energized at contact 735, by battery, conductor 718, contact 689, conductor 719, and a normally closed battery at breaker 761. This battery is open at breaker. the end of each call phase, releasing relay 730, which is re-energized by the battery, on one or other of the recovery conductors P U-1. or P U - 2 which precede the selected code, depending on whether the relay
840 is attracted or not.



   The energization of relay 860 when the first digit is
2 has been described. Similarly, relay 860 is also energized, as is relay 840, when the first digit is 3; relay 850 is energized for a first digit 4 and in combination with relay 840, or for digit 5. The relay
850 transfers the IO-50 conductors to another group of tens relays. Thus, the first digit also determines which of the two tens relay groups is used for each communication.



   Measurement of the duration of communications - ----------------------------------------
The common timer 760 'is well known, and therefore is not shown in detail. It operates in cycles with intervals of about two minutes, during which conductors 617 and 619 are normally grounded, while conductors 616, 618 and 609 are cut.

   During a two-minute cycle, conductor 609 is grounded twice; conductor 617 is open for one second, a minute and a half after the start of the cycle, conductor 619 is open for one second, after the opening period of conductor 617; the conductor 618 is grounded briefly, after the period of opening of the conductor 619, and the conductor 616 is

  <Desc / Clms Page number 34>

 grounded for a short time after the period following the. closed period of the conductor 618. The two-minute cycle just described is repeated constantly for the duration of the call.



   When the finder-connector circuit is grasped, and the relay 660 is energized, as previously described, a circuit is prepared at contact 669, to actuate relay 670 as soon as the conductor 616 of the file is grounded. the following circuit: the conductor 616 to earth, the contacts 608, 669, 647 and 685, the upper winding of the relay 670 and the battery. The relay 670 closes at contact 674 a holding circuit for itself, by its lower winding, through earth, contacts 662, 691, 603, conductor 692, contact 774, conductor 708, contacts 679 and 648 in multiple, and contact 686 up to maintenance contact 674.

   At contact 673, relay 670 prepares a circuit to energize relay 680 by timer conductor 618, which is not earthed for an interval of about two minutes. If a digit is numbered and logger release relay 690 is actuated, as previously described, before timer conductor 618 is grounded, contact 691 opens the hold circuit for relay 670, described. above, which repeats, until another earth pulse is connected to lead 616 of the timer. Assuming now, that the digit is not numbered within two minutes, earth at duntimer conductor 618 then energizes relay 680 through contact 673 and the lower winding of relay 680.

   Relay 680, at contact 683, holds on to earth conductor 655. At contact 681, relay 680 disconnects earth from relay 640, which drops out.



  At contact 642, relay 640 opens the circuit of relay 660, which also drops out. On contact 664, relay 660 releases the finder circuit; it releases the line circuit at contact 661. The holding earth is disconnected at contacts 662 and 667, and the

  <Desc / Clms Page number 35>

 relays 670 and 680 as well as the other relays of the connection circuit return the connector to its rest position.



   This delayed interrupt does not occur when it comes to an attendant or special communications, for which relays 644 and 625 are drawn. These relays control relay circuit 670 through their contacts, so that the interrupt control circuit is cut.



   If a communication between local subscribers progresses until the moment when the called subscriber answers and the relays 700 and 676 are actuated, as described previously, the timing circuits are temporarily put out of service, since the relay 676, at contact 677, connects earth to contact 662, through contacts 672, 682, 612 and 655, to keep relay 640 energized when relay 680 is energized first. Relay 680, it will be remembered, is energized after relay 670 is pulled; when timer conductor 618 is grounded. In this case, since the called subscriber has answered, relay 640 is kept energized, as described above. The relay 670 is then maintained at the earth conductor 619 of the timer at contact 687.

   About two minutes after the energization of the relay 680, the earth is disconnected from the conductor 619 of the timer, thus opening the circuit, holding the relay 670, which drops out. At contacts 671 and 672, the earthed conductor 617 of the timer is substituted for the earth of contact 662. Approximately two minutes after the release of relay 670, the earth is disconnected from conductor 617 of the timer, from where it is As a result, the relay 640 drops off, to release the link as explained previously.



   A warning signal is transmitted to the calling subscriber before the link is released, by the pick-yp relay 730 In short, the timer conductor 609 is earthed, before the earth is disconnected from the conductor 609, to activate pick-up relay 730 via contacts 675 and 688 and the driver

  <Desc / Clms Page number 36>

 
709. The relay 730 closes circuits (not shown) connecting an acoustic signal to the conversation conductors, to inform the subscribers that their conversation time is coming to an end and that the communication will be automatically interrupted at short notice.



   P.B.X Service ..



   For the sake of explanation, it will be assumed that set "B" on line L216 calls a PBX subscriber having junctions corresponding to outputs such as C 271 and C 276, by dialing the first junction of the group, i.e. 271, followed by the ringing digit. I.



   The operation of the equipment shown in Figures 2 to 10 is the same, by numbering 2701, as that described for station B calling station 2701, except the 3rd. digit 1 which is replaced by 0. The description will therefore not be repeated.



   You only need to know that the calling line is extended using dial pulses, as described above. After the 2nd. digit, relays 610, 630, 640, 660,
910, 900 and 1030 are excited. After the 3rd. number, the energization of relay CI is followed by that of relay 830 and the release of relay 970. This last relay closes a circuit to contacts 972 and 973 to energize relay 1200 through contact 875 .

   The relay 1200 circuit includes: earth, contact 662, conductor 855, contact 834, conductor 729, contacts 972 and 973, 904, 922, conductor 6 of cable 968, contact 875, conductor 743, contact 1032, conductor TA, relay winding 1200, contacts 1203 1223, 1241, cascade contacts 1214, 1204, contact 1231 to the battery, to resistor 1232. At contact 1202, the relay 1200 closes a battery holding circuit; he opens it. chain of contacts to contacts 1203, 1204, to prevent similar relays, such as relay 1210, from being energized during the junction selection period.

  <Desc / Clms Page number 37>

 



  As a result, the group access relays of the. fig. 12 can only allow the passage of one communication at a time.



   At contact 1201, relay 1200 energizes relay 1280, by earth at contact 1201, the TG conductor, contact 1031, the PBX conductor to the battery at ralais 1280. The relay.



  1280 prepares with relay 1200 a circuit in which one of the relaia of units 1010, 1020 which corresponds to a free PBX line is energized. Each line in the PBX group controls a corresponding relay, such as relays 1510, 1520, 1530 or 1540, which is energized when the line is busy, opening the circuit to the corresponding units relay.



   Suppose all the junctions are busy except the last one, in which case the relays 1510, 1520 and 1530 are energized. In this case, the units relay 1010 is energized according to the earth, the contacts 1513, 1523 and 1533, the conductor 1501 of the cable 1500, the: contacts 1283 and 1207,,. the conductor VI-6 of the cable: 1290, the winding of the relay 1010 and the. drums-. It was reported during the. previous description ,. that each unit relay controls the links to two lines. The lines with the unit numbers I to 5 intervene when the units switching relay 1000 is not energized, and the lines 6 to 0 when it is energized.

   Since PBX line number 6 is the first free PBX line, a circuit can be drawn to energize relay 1000 according to ground, contacts 1531, 1521, 1511, conductor 1506, contacts 1282 and 1206, conductor VS of the 1290 cable, the winding. lower relay 1000 and the battery.



  Relay 1000 is earthed, to conductor 698, by contact 1007. Relays 1010, 1030 and 1000 extend the PBX line number 6, connected to conductors 1077, 1078 and 1079, to conductors 637, 652 and 659. . A multiple holding circuit

  <Desc / Clms Page number 38>

 for the IOIO relay is closed at contact 1018, by earth to conductor 698, in series with relay 920. Relay 920 is shunted by earth to the winding of relay 1010, and does not operate at this time. At contact 1017, relay 1010 energizes relay 690, depending on the earth, conductors 698 and 986, contacts 918 and 928, conductor 706, relay 690 and the battery. At contact 691, relay 690 opens the maintenance circuit of relays 830 and C, which drop; contacts 834 and 875 open.

   Contact 875 opens the circuit of relay 1200; which drops and opens contact 1201, disconnecting the earth of the TG conductor. Relay 1280 drops. On falling, relay 1200 opens contacts 1206 to 1205 ', among which contact 1207 eliminates the earth at conductor VI-6 which bypasses relay 1010. Relay 920 is now energized in series with relay 1010, and the equipment common shown in fig. 12 and 15 is ready to establish a new communication.

   At contact 928, relay 920 opens the circuit of relay 690; it prepares, at contact 925 a circuit according to which the relay 780 is excited in series with the cut-off relay connected to the cohducer 1079. The operation of the relays 920, 780 and 690, the numbering of the ringing number I, l energization of relay CI, followed by relays 830, 710 and 730, connection of the call circuit to relay 750, via relay 740, response to the call via excitation of relays. 740, 700 and 620, are identical to the operations described for the last digit in the case where the number 2701 was called.

   The transmission circuit between the called line connected to conductors 1077 and 1078 is closed on the calling line, connected to conductors 508 and 509, by capacitors DI and D2. Battery power for the microphones on the calling line derives from line relay 610, and, for the called line, from relay 700, through contacts 794, 796, 781, 782. Relays 610 and 700 are energized by their

  <Desc / Clms Page number 39>

 respective lines ;. Relay 610 controls relays 630, 640 and 660, and, relays 900, 910, 920, 780, 1000, 1010 and 1030 are held by contact 667 earthed. The release of the bond takes place as described above.



   If all the: lines are busy including the. line 6, the units relay excitation circuit; corresponding is not open, by relay 1540 of the. last line, therefore, the; relays IOIO and 1000 are energized, as described above. However, driver 1079 is ibis. to earth on a busy line, and therefore the busy relay 770 is energized before the relay 920 is energized, according to the following circuit: earth to conductor 1079, contacts: 1056, 1016, 1006 , driver 659,. contact 924, conductor 658, contact 605, conductor 657, relay 770 and the battery. Relay 770 is held to earth, to conductor 655, through contact 773, and connects the busy signal to the calling line, to contact 771.

   At contact 776, relay 770 opens the incomplete circuit of relay 780, to prevent extension to the called line of a closed circuit. Except for energizing relay 770 which replaces relay 780, the relays operate identically as described previously.



   The established call is released as described in the above.



   It should be noted that free PBX trunks are pre-selected. As a result, the time required to establish the described link and energize the units relay 1010 by the relays I200 and I280 of the common equipment is less than the time delay of a delayed tripping relay, such as I240. For this reason, provision is made for the release of the common equipment in the following manner, if the connection is not established within a given time. Relay 1200 at contact 1205 energizes relay 1220 so that the normally energized relay 1240 circuit is opened at contact 1221.

   Under normal conditions, the relays

  <Desc / Clms Page number 40>

   1200 and 1220 should drop out and re-energize the 1240 time release relay before it drops out completely. The relay 1230 introduces at the contact 1231 a slight delay in the re-excitation circuit, of the relays 1200 and 1210, to prevent the relay 1240 from dropping prematurely during successive communications. However, if a communication is not established within 0.03 sec. approximately, relay 1240 drops out. The occupancy relay 770 is energized at the earthed contact 1243, by the contact 1204 ', the conductor 659, the contact 924, the conductor 658, the contact 605, the conductor 657, the relay 770 and the bat - terie.

   At contact 774, relay 770 disconnects the earth of conductor 708, and relays 830 and CI drop out, opening the circuit of relay 1200. Relay 1200 drops out as well as relays 1220 and 1230, and relay 1240 is energized again. . Relay 1280 drops out when contact 1201 is open.



   The occupancy relay 770 is kept energized by the earth to the conductor 655, by the contacts 798 and 773; it connects to contact 771 a busy signal on line conductor 639, through conductor 635, capacitor D3, contact '661', conductor 636, contact 796 and conductor 639.



  Communications between, different offices.



  We will now describe how the subscribers can reach the different groups of trunks by numbering numbers of a single digit, 7, 8, 9 or 0. A calling station is extended to conductors 508 and 509 of the connector; the operation of relay 610, responding to dial pulses, of auxiliary pulse relay 630, and of relays 640 and 660 is the same as that described in a previous chapter, in the case of station B extending a communication on. line 270.

   Station B now requests communication with exchange 16, via repeater 1600, corresponding to the outputs of

  <Desc / Clms Page number 41>

 connector lines such as C 205, first numbering the number 7. It is understood that the outputs C203 and C204 of the connector (preceding C205) although not shown, are also junctions towards the exchange 16 and are busy.



   Relay 610, together with relay 630, follows the dial pulses; the: relays 640 and 660 remain - ,, attracted between the pulses, and relay 970 is energized when contact 634 is first closed. One of the counter relays CI to C7, followed by the corresponding relay 830, 820 or 810 , is attracted in response to each of the. impulses. After 7 pulses, relay C7 and relay 830 are energized. The excitation circuits of the relays 1040, I200 and 1270 are prepared at the contacts 834, 896, 898 and 899.

   Relay 970 drops out, allowing the above circuits to operate. The 1040 cpm relay excitation circuit carries: earth, contact 662, conductor 655, contact 834, conductor 729, contacts 972, 973, 903 and 914, conductor 2 of cable 968, contact 896, conductor II of cable 968, coil of relay 1040 and battery. A circuit for maintaining relay 1040 is closed at contact I042 by conductor 984 and the winding of a relay 900, to earth at conductor 698. Relay 900 is shunted by earth to the relay
1040, and is not attracted at this time.

   Relay 1040 extends line group 0 to the respective unit relays, including. conductors 1087 ,. 1089 and I09I are extended to contacts I02I 1022 and 1023.



   The excitation circuit of the I200 relay comprises: earth, contact 662, conductor 655, contact 834, conductor 729, contacts 972, 901, 912, 911 and 971, conductor 8 of cable 968, contact 898, the TA conductor of cables 969 and 1020, the winding of the relay 1200, the contacts 1203, 1223, and
1241, the chain of contacts I2I4-I204, the contact I23I, resistor 1232 and the battery;

   An individual holding circuit for ,,,

  <Desc / Clms Page number 42>

 relay 1200 is closed at contact 1202, before the chain is opened at contacts 1203 and 1204. At contact 1201, relay 1200 connects earth to the TG conductor of cables 1290 and 969, through which relay 1270 is energized, by contact 899, conductor G 7 of cables 969 and 1290 and the battery in 1270. Relay 1270, in conjunction with relay 1200, extends the connections of the unit relays to the group junction selection relays of junctions "7" (fig. 14).



  The first two junctions of group "7" are shown as being occupied; in this case, the relays 1400, 1410, 1420 and 1430 are de-energized. The last junction is free, and therefore the relays 1440 and 1450 are energized, to preselect this free junction, the relay 1440 being energized by the capacitor 1443, from the earth to the repeater 1600. In this case; the third trunk of group "7" is preselected; this junction comprises the conductors 1087, 1089 and 1091, extending to the repeater 1600, and terminating at the contacts 1046, 1047 and 1048 of the connector of FIG. 10.

   Since 1 third junction is preselected, a 1020 units relay actuation circuit can be traced as follows from ground to contact 1451, conductor 1485 of cable 1480, contacts 1277 and 1202 ', conductor U 5 - 0 from the 1290 cable, to the coil of the 1020 unit relay and the battery. At contacts 1021, 1022 and.



  1023, relay 1020 extends conductors 1087, 1089 and 1091 to conductors 637, 652 and 659, through contacts 1001, 1003 and 1005. A holding circuit is prepared for relay 1020 through contact 1029, conductor 985, l winding of relay 920 and conductor to earth 698. Relay 920 is grounded to conductor U 5- O, and is not energized at this time.



  Relay 1020 closes a circuit to energize relay 600, as follows: from conductor 698 grounded by contact 1028, conductor 986, contact 919, conductor

  <Desc / Clms Page number 43>

 742, contact 777, conductor 707, to the coil of relay 600 and the battery. At contacts 60le, 601, 602 'and 602, relay 600 transfers conductors 508 and 509 of the calling line from line relay 610 to conductors 637 and 652, through which relays 1765 and 1760 of repeater 1600 are energized directly through the calling line. The operation of the repeater will be described in a separate chapter.

   At contact 604, relay 600 connects earth to conductor 1091, in order to cause relay 1440 to release, so that the junction selector relays of Figure 14 can immediately preselect the next free junction. The following operations take place in response to the closing of contact 604: relay 1630 of repeater 1600 is energized by earth contacts 642, 661 and 604 .; lead 659, contacts 1005, 1023, and 1048, lead 1091 extending to repeater 1600 of Figure 16, contact 1859, lead 1795, top coil of relay 1630, and the battery.

   At contact 1632, the earth is disconnected from conductor 1443, to release relay 1440, which drops out, and causes the next free junction to be preselected by the selection relays.



   At contact 603, relay 600 disconnects the earth at contact 663 of conductors 692 and 708, to drop relays 830, C 7 and 1200. At contact 834, relay 830 eliminates the earth shunt of relay 900 , which is then excited in series with the relay 1040, by the contact 1042. At the contact 906, the relay 900 prepares the circuit of the switching relay of units 1000, which intervenes only in case a communication with digit of units 6 to 0 is requested. Relay 1200 drops, and drops relay 1270. The earth bypassing relay 920 is disconnected at contacts 1202 'and 1277, with the result that the relay

  <Desc / Clms Page number 44>

 920 is then energized, in series with relay 1020, by contact 1029.

   The relays 1040 and 1020 are kept attracted by the ground conductor 698, through the winding of the relays 900 and 920. The common equipment of Figures 12 and 14 is then made available for establishing new communications. When the repeater line relays operate, a ground is returned to conductor 1091, to keep relay 660 energized, and to keep conductor 594 to earth, as a result from conductor to ground 1091, by contacts 1048 , 1023 and 1005 the conductor 659, the contact 604, the conductor 594, the contact 661, until the winding of the relay 660 and the battery.

   Line relay 610 drops out when relay 600, at contacts 601 'and 620', and 601 and 602, transfers the calling loop to the repeater.



  At contact 611, relay 610 releases relay 630, and opens at contact 612 one of the multiplied earth circuits of relay 640.



  At contact 632, relay 630 energizes relay 650, without effect at this time; on contact 633 it opens the circuit of relay 640, which drops out after an interval. At contact 643, relay 640 opens the circuit of relay 650, which drops out and opens at contact 642 the initial excitation circuit of relay 660, which is then kept attracted by the repeater. The control of the link is then under the control of the repeater 1600.



   It seems useful at this point to describe in detail how the junction selection relays, as shown in Figure 14, preselect free junctions. When the repeater 1600 is seized, either by an outgoing communication or by an incoming communication, the earth is disconnected from the conductor 1443 to drop the relay 1440. On contact 1441, the relay 1440 closes a circuit to activate the relay 1460 ,, from earth to contacts 1453 and 1441. At contact 1461, relay 1460 opens the circuit of delayed release relay 1470, which does not drop out.

  <Desc / Clms Page number 45>

 only after a determined time. On contact 1462, relay 1460 opens the holding circuit of relay 1450, which drops out.

   At contact 1451, relay 1450 disconnects the marking earth of conductor 1485, to control the corresponding unit relays of the connector. Now assuming that the first two junctions are free, the two relays 1400 and 1420 are energized by the normal earth connections coming from the corresponding repeaters similar to the repeater 1600. When the relay 1450 dropped, the contact 1453 was open, with this result. Relay 1460 drops out and restores the circuit from relay 1470 to contact 1461, before relay 1470 has had time to drop completely.



    A circuit can now be drawn to actuate relay 1410 as follows from ground to contacts 1452, 1432 and 1402, through the coil of relay 1410, contact 1462, to resistor 1463 and the battery. At contact 1411, relay 1410 grounds conductor 1483, to mark the first junction, so that the corresponding units relay of a connector will be actuated when the junction group is called. At contact 1412, relay 1410 closes a holding circuit for itself, as follows: from earth to contact 1454, according to contacts 1434 and 1412, the winding of relay 1410 and resistor 1463, up to battery 1463.

   At contact 1413, relay 1410 prepares a pick-up circuit to energize relay 1430, this circuit acting if, for some reason or another, the connector does not establish the desired link before the relay de-energizes. timed tripping 1240. When this first junction is taken in service, the relay 1400 drops off, and closes a circuit to energize the relay 1430 as follows; from earth, through contacts 1452, 1432 1401 and 1422, the winding of relay 1430, contact 1462, to resistor 1463 and the battery.

   At contact 1431, relay 1430 connects an earth

  <Desc / Clms Page number 46>

 marking to conductor 1484, to mark the preselection of the second junction, and closes a holding circuit for itself, by earth at contact 1454. At contact 1432, relay 1430 opens its initial excitation circuit, after having closed its holding circuit; at contact 1433, it closes a multiplied circuit for itself; at contact 1434, it opens the holding circuit of relay 1410, which drops out, and at contact 1436, it prepares a recovery circuit for relay 1450. At contact 1411, relay 1410 disconnects it. marking ground of conductor 1483, and prepares at contact 1414 another point of the pickup circuit of relay 1450.



   When the second junction is taken in service, and assuming the third junction is free, relay 1420 drops out, and closes relay circuit 1450 as follows: by ground, contacts 1452, 1433, 1421 and 1442, the winding of relay 1450, contact 1462, resistor 1463 and battery.



  At contact 1451, relay 1450 connects the. marking ground to conductor 1485; it remains in contact 1455, through contact 1462; in 1452 he opened his initial excitation circuit; it closes in 1453 a multiplied circuit for itself, it opens in 1456 the holding circuit of relay 1430, which drops out and prepares at contact 1456 a recovery circuit for relay 1460. Relay 1430, when falling, disconnects on contact 1431 the marking ground of conductor 1484; it prepares in 1437 another point of the circuit of relay 1460. The junction selection relays are then in the position shown in figure 14.



   In the event that the connector does not establish the link, for some reason, relays 1200, 1220 and 1230 are kept energized long enough to allow relay 1240 to drop out and actuate the connector occupancy relay. , in the manner described above. In addition, relay 1240 closes, on contact 1242, the junction selector relays recovery circuit, to obtain the pre-selection of the free junction // It

  <Desc / Clms Page number 47>

 next.

   In the case where the first junction in fig. 14 is preselected, in which case relays 1400 and 1410 are energized, the earth at contact 1242 closes the circuit, recovery, to excite relay 1430, if the 2nd. The junction is also free, as follows: from the earth contact 1242, through contact 1271, conductor 1468, contacts 1413, and 1442, the winding of relay 1430, up to resistor 1463 to battery. Relay 1430 is drawn; it marks the 2nd, junction, and releases the relay 1410; as described above. Similarly, relay 1450 or relay 1460 can be energized by the recovery circuit, by contact 1242.



   In the event that all three junctions are occupied, relays 1400 to 1450 inclusive are all de-energized, and relay 1460 is energized by contacts 1452, 1432, 1401, 1421 and 1441.



  Relay 1470 is released, and resets conductor 1487 to earth, to contact 1471. If a communication is transmitted to the 7th. group of junctions, at a time when all these junctions are occupied, the occupancy relay 770 of the connector is actuated, according to the following circuit: earth, contact 1471, conductor 1487, contacts 1279 and I204 ', conductor 659 of cable 1290, contact 924, conductor 658, contact 605, conductor 657, occupancy relay winding and battery.



  On contact 774, occupancy relay 770 opens the circuit of relays 830 and C7, which drop; is maintained by contact 773 to the earth conductor 655. At contact 834, relay 830 opens the circuit of relay 1200, and also eliminates the shunt by earth of relay 900, which is then energized in series with relay I040. No unit relay is actuated at this time; 'because there is no marking earth on the junction selection relays of fig. 14. The busy relay transmits the busy signal to the calling subscriber who then hangs up, to release the partially established link.

  <Desc / Clms Page number 48>

 



  Group junctions 8.



  Fig. 13 represents the group access relays and the trunk selector relays of the trunk group 8. Since this group of trunks is subject to. Considerable traffic, a separate set of group access relays are provided, to allow communication over that group of trunks from one connector, while another connector can be busy. establish a communication on the PBX group, or on the groups 7, 9 or 0. As a result, simultaneous communications can be established from different connectors, on the trunk group 8 and on one of the other groups mentioned.

   Simultaneous communications from different connectors cannot be transmitted, however, by the same group access relay, because of the chain circuits controlling the relay excitation circuits, such as 1200, 1210, I300. 1310. The group access relays of FIG. 13 are similar to those of FIG. 12, and the junction selection relays of fig.



  13 are similar to those in. fig. 14. The first of the two junctions shown in FIG. 13, of group 8, is occupied, relays 1340 and 1350 being de-energized, while the 2nd. junction is represented as being free, and preselected with relays 1360 and 1370 energized.! ... At contact 1371, relay 1370 connects, and a marking earth at contact 1305, to preselect the corresponding junction, from so as to actuate the corresponding unit relays of the connector.



   Now suppose that the. calling line wishes to call trunk group 8, and dials digit 8. The extension of the calling line, through the searcher, as well as the numbering, is the same as described for the numbering of the digit 7, except that rela.is C8, followed by relay 820, is energized after 8 pulses. After relay 970 has closed its contacts 972 and 973, the relay contacts 802 and 803

  <Desc / Clms Page number 49>

 C8 are able to energize relays 1030 and 1300, from conductor to earth 655.



   The excitation circuit of relay 1030 is as follows: conductor 655 to earth, contact 824, conductor 729, contacts 972, 901 and 912, conductor 3 of cable 968, contact 802, conductor 9 of cable 968, the contacts of the restricted traffic relays. 930 950. These relays will be described in detail in a following chapter. It suffices simply to admit, for the moment, that the station is in group B, and that relay 940 is energized. The circuit previously described for conductor 9 of cable 968 is extended, to contacts 933 and 934, to conductor 981 and to; the battery to 1030. The relay 1030 attracts, and a multiplied holding circuit for itself closes at the contact 1034, by the earth when the relay 900 flows. The relay 900 is bypassed, and. is, not excited at this time.

   Relay I030 extends the ten lines to the unit relays, to the C271-C270 outputs of the junctions. The circuit, relay excitation. I300 is closed by conductor 655 at the. earth, contact 824, conductor 729, contacts 972, 901, 912, 911 and. 971, conductor 8 of cable 968, contact 803, TA conductor 8 of cables 969, and 1290, coil of relay 1300, contacts I302 and 1331, chain. of contacts 1313-1303, the contact, 132.6, la. resistor 1327 and the battery. A multiplied holding circuit, for relay 1300, is closed at contact I30I, before the contacts. 1302 and. 1303 have opened the excitation circuit common to all group access relays, such as 1310.

   At contacts 1305, 1308 ', the relay 1300 extends the circuits of the melais units from the connector to the relays. selection of. junctions, correspondents.



  The last junction being. free ,, the earth at contact 1371 is extended by contact 1305 'to the conductor V5-O, through which the. relay I020 is energized. Relay. I020 extends the conductors, from line, through contacts-, 1021, 1022 and 1023, to the conductors. 1074, 1075 and. IQ76 of the repeater 1900 of fig. 19.

  <Desc / Clms Page number 50>

 



     At contact 1028, relay 1020 closes a circuit to energize relay 600 through conductor 698 to ground, contact 1028, conductor 986, contact 919, conductor 742, contact 777, conductor 707, winding of relay 600 and battery. At contacts 601 and 602, relay 600 connects calling conductors 508 and 509 directly to conductors 637 and 652, thus closing a circuit through contacts 1001 and 1003, 1021 and 1022, 1051 and 1052 and conductors 1074 and 1075, to the repeater 1900 of fig. 19, to energize the repeater line relays 2005 and 2000.

   At contact 604, relay 600 closes a circuit to earth on conductor 1076 extending to repeater 1900 as follows: from earth, through contacts 642, 661 and 604, conductor 659, contacts 1005, 1023 and 1053, up to conductor 1076. Ground conductor 1076 causes the repeater relay 1945 to be energized, which removes the earth from conductor 1999, to release relay 1360. On contact 1361, relay 1360 closes the circuit for energize the recovery relay 1380, by the conductor to the earth, 1373. At contact 1382, the relay 1380 opens the holding circuit of the relay 1370, which drops out and removes the marking earth at the contact 1371.

   Assuming that the first junction is free, relay 1340 is then energized, and when relay 1370 drops out, it opens the circuit of relay 1380, and closes the following circuit for relay 1350: from earth, through contacts 1372 and 1342, the winding of the relay 1350, the contact 1382 and the resistor 1383 up to the battery.

   Relay 1350 is engaged, and preselects the first junction, by closing contact 1351. The following operations of the junction selector relays, including the recovery circuit to pre-select the next free junction, if the connector does not establish the connection within a determined time, as well as the arrangement of the circuits enabling relay 1390 to be released, to close contact 1391 and activate the connector occupancy relay, in the event that all the junctions are occupied.

  <Desc / Clms Page number 51>

 weights at the time communication is requested, are the same as those described in the case of group 7.

   At contact 6.03, relay 600 opened the circuit of relays 820 and C 8, which fell back; on contact 824, relay 820 opens the shunt of relay 900, which thereby becomes energized, in series with relay 1030, by contact 1034, to keep relay 1030 attracted. Contact 824 also opens the circuit of relay 1300, which drops out. On contact 1305 ', relay 1300 opens the shunt of relay 920, which then becomes energized in series with relay 1020 by contact 1029 to keep relay 1020 energized.

   Relay 1300, on falling, causes relay 1320 to drop back to contact 1304; it re-establishes at contact 1321 the circuit of relay 1330, before it has completely dropped out, and opens at contact 1322 the circuit of relay 1325, which again reconnects, at contact 1326, battery resistor '1327, to allow group access relays to be used during another communication transmitted on group 8.



   When the 1900 repeater line relays are operating, ground is returned to conductor 1076, to keep relay 660 energized and to keep conductor 594 grounded, before the delayed trip relay. 640 has fallen.



  Line relay 610 drops out when the relay. 600 is drawn in, to release relays 630 and 640, as previously described. Since the relay. 660 is then kept energized by the repeater, control of the link is now transferred to it.



  Junction group 9.- ----------------------
The lower part of FIG. 11 shows the group 9 trunk selection relays; is similar to group 7 shown in FIG. 14, except as regards the arrangement enabling communications to be transmitted in the event of congestion.

  <Desc / Clms Page number 52>

 cations of junction group 0 to group 9. Access to these junction selector relays is made by means of the group access relays and the junction group relays in figure 12.



  As shown in the. lower part of Figure 11, only the direct junction selector relays are shown, and these junction are assumed to be free; therefore relays 1160, 1180, and 1194 are energized by extended earth by their respective repeaters, such as repeater 2000 (Figure 21-23). Relay 1169 is actuated to preselect the first free junction of group 9, by earth, contacts 1174, 1188 1168;

     the winding of the relay 1169, the contact 1124 ', the resistor 1126', and the battery. At contact 1162, relay 1160 activates congestion relay 1130, to prepare the circuit for preselecting the first junction of group 9, as congestion junction, in the event that all 0 junctions are occupied.



  Since the first junction of group 9 is the sixth junction accessible by the tens relay contacts 1040, the relay 1169, at contacts 1165 and 1167, places a ground on the conductors 1226 and 1227, in preparation for the actuation of the relay of. actuation of 1000 units and ten relays of 1010 units, when this group of junctions is called.



   We will now assume that the calling line wishes to establish a communication with a trunk of group 9. The extension of the calling line by the searcher and the operation of the connector .: 'in response to the numbering of the digit 9 is the same is the same as that described for number 7, except that in this case the relays C 9 and 810 are energized, after 9 pulses After the relay 970 has closed its contacts 971 to 973, the relay C 9, to contacts 806 and 807 closes circuits to energize relays 1040 and 1200, from conductor to ground 655.

   The relay 1040 excitation circuit consists of: conductor 655 to earth

  <Desc / Clms Page number 53>

 contact 814, conductor 29, contacts 972, 973,903 and 914, conductor 2 of cable 968, contact 806, conductor 10 of cable 968, contact 947, coil of relay 1040 and the battery. The circuit (the excitation of the relay 1200 comprises: the conductor to the earth 655, the contact 814, the conductor 729, the contacts 972, 901, 912, 911 and 971, the conductor 8 of the cable.



  968, the contact 807, the TA conductor of cables 969 and 1290, the winding of the relay 1200, the contacts 1203, 1223 and 1241 ,, the chain of contacts 1214 and 1204, the contact 1231, the resistor 1232 and the drums.



   Relay 1040 is energized by the previous circuit, and closes a hold circuit for itself, through contact 1042, conductor 984 and transfer relay winding 900, to the ground conductor. 698. Relay 900 is shunted by earth energizing relay 1040, and cannot be energized at this time. Relay 1040 extends the 10 lines to the connector unit relays. Relay 1200 is energized according to the previous circuit, and closes a hold circuit for itself, through contact 1202, before contacts 1203 and 1204 have opened, to prevent further group access relays, such as relay 1210, to be attracted at this time.

   At contact 1205, relay 1200 activates relay 1220, which holds relay 1200 hold circuit at contact 1224 when relay 1230 is operating, and opens this circuit at contact 1231.



   At contacts 1206 to 1205 ', inclusive, relay 1200 extends the conductors of cable 1290 to contacts 1261 to 1269, inclusive of junction group relay 1260. At contact 1201, relay 1200 closes a circuit to actuate relay 1260, as follows: by earth, contact 1201, conductor TG of cables 1290 and 969, contact 808, conductor G 9 of cables 969 and 1290, the winding of relay 1260 and the battery. At contacts 1262 to 1269, relay 1260 extends the conductors of cable 1290 to ..

  <Desc / Clms Page number 54>

 the group 9 junction selector relays, shown in the lower part of the, figure 11.

   Circuits can now be drawn as follows to energize the units switching relay 1000 and the units relay 1010. The relay 1000 circuit consists of: earth, contact 1165, conductor 1226 of cable 1234, contacts 1262 and 1206, conductor U 5 of cable 1290, the winding of relay 1000 and the battery. The JOJO relay circuit includes: earth, contact 1167, conductor 1227 of cable 1234, contacts 1263 and 1207, conductor U 1- 6 of cable 1290, coil of relay 1010 and battery.



   The units switching relay 1000 switches ;, at contacts 1002, 1004 and 1006, the line and test conductors of the connector to contacts 1014, 1015 and 1016, and at contact 1007 closes a holding circuit for itself. even;. by the conductor to earth 698. The relay of units 1010 connects, to contacts 1014, 1015 and IOI6, the line and test conductors of the connector to conductors 1092, 1093 and 1094 of the repeater, through the contacts 1061, 1062 and 1063 of relay 1040. At contact 1018, relay 1010 closes a holding circuit for itself, through conductor 985 and transfer relay winding 920, to the ground conductor 698.

   Relay 920 is shunted by the earth which energizes relay 1010, and therefore is not attracted at this time. At contact 1017, the relay closes a circuit to energize the connection relay 600, as follows: by the conductor to ground 698, contact 1017, conductor 986, contact 919, conductor 742, contact 777, conductor 707, relay winding 600 and the battery.



   At contacts 601 and 602, relay 600 connects the calling loop directly to repeater conductors 1092 and 1093, to energize line relays 2145 and 2140 thereof. At

  <Desc / Clms Page number 55>

 contact 604, relay 600 closes a circuit to earth through contacts 642, 661, 604, conductor 659, contacts I006 IOI6 and 1063, for conductor 1094, so as to energize line relay 2110, which opens the relay circuit 1160, to release it.

   At contact 1163, relay 1160 closes a circuit to energize relay 1190 as follows: by earth, contacts 1199, 1186, 1163 and 1183, the winding of relay 1190, contact 1124 ', resistor 1126' and the battery. At contacts 1184 and 1185, relay 1190 earths conductors 1226 and 1228, to preselect the next junction; it closes on contact 1198 a holding circuit for itself, by earth on contact 1174; it opens on contact 1186 its initial excitation circuit; it closes at contact 1187 a circuit multiplied for itself, by the earth at contact 1199; on contact 1188 it opens the circuit of relay 1169, which drops out; it also extends, at contact 1191, the recovery circuit to relay 1176.

   Relay 1169 drops out, and removes the marking earth from conductors 1226 and 1227, at contacts 1165 and 1167, and extends the pick-up circuit at contact 1171 to relay 1176.



  * Relay 600 also opens at contact 603 the circuit of relays 810 and C 9, which drop out. At contact 814, relay 810 opens the shunt of relay 900, which is then energized in series with relay 1040, by contact 1042, to keep relay 1040 attracted. Contact 814 also opens the circuit of relay 1200, which drops out. At contact 1207, relay 1200 opens the shunt of relay 920, which energizes in series with relay 1010, through contact 1018, to keep the IOIO relay engaged.



  On contact 1205, relay 1200 opens the circuit of relay 1220, which drops out. At contact 1224 ,. relay I220 disconnects battery resistor 1232 from the chain of contacts; it prepares for contact 1223 a point in the circuit to activate an access relay

  <Desc / Clms Page number 56>

 group, such as 1210; which circuit is not yet closed at this time, contacts 1224 and 1231 both being open. On contact 1221, relay 1220 re-establishes the circuit of relay 1240, before it has completely dropped out; it also places, at contact 1231, battery resistor 1232 on the chain of contacts so that a group access relay can be energized.

   The delay in connecting the battery to the chain contacts, as just described, is intended to prevent a group access relay, such as relay 1210, from being energized during power-on. a communication before the junction selection relays 1160 1169 and 1190 have had time to perform their functions, releasing the marking grounds for the first junction and to mark the second junction as the next to be preselected, as well as 'has been described previously. The relays involved must be chosen carefully so that their operating and release characteristics are such that a double connection with the same junction, or a single connection with two junctions, cannot occur.



   When the repeater 2100 line relays are operating, a ground is returned to conductor 1094, to keep relay 660 energized, and to keep conductor 594 grounded, before time-delayed trip relay 640 drops out. Line relay 610 drops out when relay 600 operates, to release relays 630 and 640, as previously described.



  Since the relay 660 is maintained by the repeater, the latter then exercises control of the communication.



  Group of junctions O.- -----------------------
The group "0" junction selector relays are similar to those of group "9", and successively assign the junctions in the same way as described for groups 7 and 9.

  <Desc / Clms Page number 57>

 



  To the. fig. 11, only the remakes of two junctions have been shown, and it is assumed that the first junction is free, and preselected, the relays 1100 and 1106 being actuated while the second junction is occupied, the relay 1110 being de-energized. The relay II06 is kept attracted by the earth, the contacts 1117, 1105, the winding of the relay 1166, the contact 1124, the resistor II26 and the battery. Since the first junction of group "0" is the first junction which is accessible through 1-through the contacts of the tens relay 1040, the relay 1106, to the contact 1104;,. place a ground: to conductor 1236, to pre-select the units relay ', such as relay 1010.



   We will now assume that the calling line wishes to obtain a communication with. a junction of group "0". The extension of the calling line through the pager and the operation of the connector in response to the numbering of the digit "0" occurs. same as described for group 9, except that in this case the CO counter relay and relay 830 are actuated after ten pulses. After relay 970 drops out, the CO relay closes at the contacts. 816 and 819 of the circuits to energize, relays 1040 and 1200, from the conductor to earth 655.

   The circuit to energize the relay. 1040 is as follows ,. the earth- conductor 655, the contact 834, the conductor 729, the: contacts: 972, 901 and 912, the conductor 3 of the cable 968, the contact 816, the conductor 11 of the cable 968, the winding said relay 1040 and the battery. The relay 1200 excitation circuit comprises: the earth conductor 655, the contact 834, the conductor 729, the contacts: 972, 901, 9 and 971, the conductor 8 of the cable 968, the contact. 819, the TA conductor of the cables, 969 and 1290, the winding of the relay 1200, the contacts 1203, 1223, 1241, 1214, 1204 and 1231, la. resistor 1232 and the battery-.



   The I040 relay closes a holding circuit for itself,

  <Desc / Clms Page number 58>

 by contact 1042, in series with relay 900, which is not energized at this moment, being bypassed, as described previously. Relay 1040 extends the 10 line outputs to the unit relays of the connector. Relay 1200 closes a hold circuit for itself at contacts 1206 to 1205, inclusive; it extends the conductors of cable 1290 to contacts 1252 to 1258 ', inclusive, and closes at contact 1201 a circuit to actuate the junction group relay 1250.

   Relay 1220 energizes relay 1230 at contact 1222; it opens the chain excitation circuit of the group access relays in 1223, and connects the battery through contact 1224, before relay 1230 opens this battery connection to contact 1231.



   The excitation circuit of relay 1250 can be traced as follows: earth, contact 1201, TG conductor of cables 1290 and 969, contact 825, GO conductor of cables 969 and 1290, relay winding 1250 and the battery. At contacts 1251 to 125SP9, relay 1250 extends conductors 1233 to 1248 to the group “0” connection selector relays in fig.



  II. In response to this connection, the pre-selected units relay is energized according to the following circuit: earth, contact 1104, conductor 1236, contacts 1253 and 1207, unit conductor VI-6, l winding of the 1010 units relay and the battery.



  To contacts 1011, 1012 and 1013, relay 1010 connects the line and test conductors, through repeater 201 ', using contacts 1043, 1044 and 1045, and conductors 1084, 1085 and 1086. At contact 1018, relay 1010 closes a maintenance circuit for itself. in series with the transfer relay 920, which is not energized at this rise, being bypassed. At contact 1017, it closes the drive circuit of connection relay 600, as described above.



   Relay 600, in the same way as we have. already described,

  <Desc / Clms Page number 59>

 connects the calling line to the connected repeater, and closes a circuit, through conductor 1086, to actuate a repeater relay which releases the junction selector relay. 1100. At contact 603, relay 600 opens the circuit, relays. 830 and CO, which fall back ,. At contact 834, relay 830 opens the: shunt of relay 900, which then attracts -, being energized. in series with relay 1040; it also opens at contact 834, the circuit of relay 1200, which drops out. On contact 1207, relay 1200 opens. the shunt of relay 920, which is then excited in series with the IOIO relay. Relay 1200 opens in 1205 the circuit, relay 1220, which drops out.

   On contact 1224, relay 1220 disconnects the battery from the relays. access of, group, to produce a slight delay before, that one of them can operate; it also opens, at contact 1222, the relay circuit, 1230, which. drop and reconnect the battery: group access relay.



   Relay 1100 drops out when the connector establishes the link; it closes on contact 1102 the circuit of the relay, 1119, if the second junction is free. It is assumed, however, in. in the present case, that the. second junction is occupied; instead of exiting relay III9, relay 1125 is energized according to the following circuit: earth, contacts 1115, 1102, 1112, winding. of relay II25 and. battery. At contact 1124, the. relay 1125 disconnects the battery from the selection relays, in order to bring them back, in the event that none of the junctions of group "0" are free, in a manner similar to that described for group "7". Relay II06 then drops, and disconnects the tagging at contact 1104.

   Relay 1100 also closes, at contact 1001, a circuit to energize relay 1136 of the bulkhead group, so that communication for the group of "O" trunks can be directed to the group. "9" when all "0" junctions are occupied. This circuit can be traced

  <Desc / Clms Page number 60>

 as follows: earth, contacts 1101, 1111, 1145, 1132, coil of relay 1136, contact 1153, resistor 1154. and la. drums.

   If the first junction of group "9" were occupied at this time, relay 1130 would be energized, and the circuit traced above would be extended to relay 1149, through contacts 1131 and 1142. When the first junction of group "9" is free, relay 1136 is energized and is maintained by earth, contacts 1101, 1111, 1147, 1135, resistor 1154 and the battery.

   At contact 1137, it prepares the recovery circuit of relay 1149; it earths, at contacts 1133 and 1134, conductors 1244 and 1236, to preselect the first junction of group "9", in the case where a communication to the 9th. group borrows this first junction, relay 1130 drops, and relay 1149 is activated, to preselect the 2nd. junction of group "9", in the event of congestion of group "0".



   Suppose now that the second trunk of group "0" becomes free before another communication is made on group "0"; relay 1100 is then energized, and appends to contact 1111 the circuit of relay 1136, which drops out and removes the markings from contacts 1133 and 1134. At contact 1112, relay 1110 also opens the circuit of relay 1136, at contact 1111 , 1136 drops out, and removes the markings at contacts 1133 and 1134.



  At contact 1112, relay 1110 also opens the circuit of relay 1125, which drops out and reconnects the battery, to energize relay 1119 as follows: earth, contacts 1115, 1102 (first junction occupied), contact 1113, the winding of the relay 1119, the contact 1124 and the resistance to the battery.



  The relay 1119 is maintained by the contact 1118, and earths at the contact 1114, the conductor 1237, to preselect this junction.



   In the event that all the junctions of group "0" and the first two junctions of group 11911 are occupied, a circuit

  <Desc / Clms Page number 61>

 can be traced as follows - to energize relay 1155: the. earth contacts 1101, IIII, 1145, 1131: and 1141, the winding of relay 1155 and battery. At contact 1153, relay 1155 disconnects the battery from the selection relays. Boundary junction II36 and 1149, and opens at contact 1152 the circuit of time-delayed release relay 1127. Relay 1127 drops out, after a certain time, and puts conductor 1247 to earth at contact II28 , so as to actuate the occupancy relay 770, in the event that a communication is routed at this time on group "0".

   As soon as any of these junctions become free, the circuit of relay II55 is opened, with the result that relay II27 is energized again, to eliminate this busy state. The recovery circuits operate in the same way as before, during a communication for group "7", in the event that relay 1240 drops out completely.



   In the event that a second connector, as shown in FIG. 13 would transmit a communication to any one of Groups 0, 9, 7 or PBX, relay 1210 would be operated in the same manner as described for relay 1200, and the connection would be established similarly, provided of course, that one of the group access relays, such as 1200, is not activated at this time for a communication on one of these groups.



  In the event that the relay I200 is actuated on a communication coming from the first connector, the relay 1210 cannot be energized, since the battery is open at contact 1223.



  The calling subscriber is warned of this, since the numbering signal is not transmitted to him, and the connector waits in its attracted position, until the relays 1200, I220 and I230 release the supply of battery, to energize relay 1210, after which the establishment of communication continues as evident from the foregoing description. Nevertheless, the

  <Desc / Clms Page number 62>

 second connector can establish a connection with the 8th group, through the group relays of the. fig. 13, at the same time that a communication is in progress via the group access relays of FIG. 12.



  Traffic restrictions and special services.- It was previously mentioned that some well-specified lines benefit from service through the junctions, while other lines are deprived of it. Likewise, incoming communications on determined junctions do not have access to. certain lines or junctions, and have access to other lines or junctions; in addition, an inter operator enjoys special service facilities, such as intervention in a call in progress, or listening, or even access to a test number, when additional dialing is required . These facilities will now be decreed. To avoid unnecessary repetitions, reference will be made to the preceding descriptions.



   The station connected to line L216, terminating at the circuit of LINE 216, (and which is one of the stations in group B) is marked at relay 480, in conjunction with the energization of relay of tens 310, of relay d. 'units 340 and connection relay 550.



  It was previously indicated that these latter relays are energized when a communication is requested, to extend the calling line to relays 510 and 520. Relay 480 is energized at the same time, by contact 311. , and relay 940 is energized at contact 485, by earth contact 341, conductor 391, contact 485, conductor 455, contact 556, conductor 455 ', lower coil of the relay 940 and the battery.



  The relay 940 maintains itself to the earth to the conductor 698 by the contact 941. At the contact 947, one of the excitation circuits of the tens relay 1040 is open; therefore, assuming the first digit numbered is 9, the circuit from contact 806 and conductor 10 of cable 968 is transferred to contacts 947 and 946 of relay 1040, to relay 960. Relay 960 is energized, and

  <Desc / Clms Page number 63>

 closes on contact 961 its own holding circuit, through conductor 984, the winding of relay 900 and earth at conductor 698. Relay 900 is shunted by earth to coil 960, and is not energized at this moment. On contact 963, relay 900 energizes the occupancy relay 770 of the connector, by earth at conductor 698, conductor 659, contact 605, conductor 657 and the battery at terminal 770.

   Relay 770 opens the pulse circuit at 775; subsequent pulses have no effect. At contact 771 a busy signal is connected to the calling line, and at contact 774, the pulse counter relay holding circuit is open, and relays C 9 and 810 drop. At contact 962, relay 800 is energized, via contact 907 and conductor 706, again opening the counter relay circuit at contact 691. It is obvious that when the calling subscriber hangs up, relays 6IO, 630 , 640 and 660 drop, disconnecting the earth from conductors 655 and 698 at contacts 662 and 667. Relays 940 and 960 drop and all equipment returns to rest.



   Suppose that station B of line L 216 numbers digit 8. Relay 940 is energized when the link is extended to the connector, and relays C 8 and 820 are energized after 8 pulses The circuit of contact 802 and conductor 9 of cable 968 is transferred to contacts 944 and 945, of relay 960 to conductor 981, through which relay 1030 is energized. Communication is established as described above. It is evident from the above description that the communications of trunk group 8 can only be transmitted if relay 940 is energized; as a result, the subscriber stations which are not arranged so as to energize the relay 940 cannot use them.



   The service restrictions applicable to a line terminating at line circuit 205 are controlled by the relay

  <Desc / Clms Page number 64>

 930. When a communication is requested, the relays 300,330,500 and 510 are energized. At contact 301, relay 420 is energized via conductor 396; at contact 331, relay 930 is energized by the contact at la. earth 351, conductor 392, contact 426, conductor 457, contact 558, conductor 457 ', lower coil of relay 930 and the battery.

   Assuming that the first two digits of requested n are 2 and 0, a circuit is extended, through which the relay 1040 is energized only when the relay 930 is energized. This circuit can be traced, after the numbering of the second digit "0" as follows: the earth conductor 655, the contact 834, the conductor 729, the contacts 972, 901 and 913, the conductor 5 of the cable 968, the contact 817, the 0 C conductor of the cable 826, the contact 868, the conductor 965, the contact 934, the conductor 11, the coil of the relay 1040 and the battery. The connection is then established in the well-known manner, as in the case of a line calling another extension.

   Obviously, relay 930 is energized only for communications from authorized lines; any other line that would call # 20 would energize blocking relay 960n and communication would be blocked, as described in the following:
It is also obvious that line 205 cannot call the trunk group? 9, since the drive circuit of relay 1030, from contact 802, is not closed to conductor 981 by contacts 932 and 942, since relay 940 is not energized.

   As a result, a communication emanating from station 205 and intended for group 8 activates relay 960, via conductor 9 of cable 968, contacts 932 and 943, and the communication is: blocked, as we have seen. described.



   Subscriber extensions ending at the same tens group as the trunk group? 8 do not normally experience

  <Desc / Clms Page number 65>

 restrictions. The excitation circuit of relay I030 is controlled, when stations are called such as those on lines 271 and 270, by contact 897, conductor 70 of cable 826, contact 864, conductor 964, contact 953, conductor 981, relay I030 and battery.



   A junction terminating at line circuit 215 cannot be reached at lines C 271 and C 270, due to energization of relay 950. Line circuit 215 energizes relays 310 and 330, together with relays 550-560 when a communication is requested. At contact 311, relay 480 is energized, closing the circuit through contact 331, conductor 392, contact 484, conductor 458, contact 559, conductor 458 'and the battery to relay 950. Auxiliary contacts 953 and 952, conductor 964 is transferred from conductor 981, through which relay I030 is energized, to blocking relay 960. Relay 960 is therefore energized when the calling subscriber forms the number 27.

   Relay 960 energizes at contact 963 the occupancy relay of the connector, as has been described above.



   Briefly, the service restriction device controlled by relays 420, 480, 930, 940, 950 and 960 works as follows: No communications are prevented from reaching the NI trunk group 7. Communications for the group 8 are normally stopped unless either relay 940, if relays 930 and 940 are energized; therefore, lines such as 200, 205 and 2IO cannot use group 8. Group 9 is accessible to all lines, except those which activate relay 940; therefore, lines such as 200, 205, 210, and 215 can call group 9, while lines such as 20I, 206, 211, and 216 cannot use it. Group "0" is accessible to all lines.

   The group P B X "C 271" is inaccessible only for line 215. Lines such as

  <Desc / Clms Page number 66>

 that 201, 206 and 205 can call group 200, while lines such as 200, 211, 216; 210 and 215 cannot.



  Obviously, any of these restrictions can be easily changed at the end conductors 455 through 458 of the D F distribution frame, and the contact connections of relays 420 and 480.



  Special services.- --------------------
It is possible to remove certain restrictive characteristics existing in the connector, in addition to the restrictions controlled by relays 930-950. For this purpose, a description will now be given of how a communication terminating at line 200 energizes relay 644 and of disabling the possibility of limiting the duration of conversations in the connector and trunk circuits.



   Communication is established from. usual way, and includes the excitation of relays 300, 350 550, 560 to attract relays 500, 530, and 540 from the connector.



   Relay 420 is energized by contact 301, through contact 396, which closes a circuit in which relay 644 is energized, depending on contact to. ground 351, conductor 390, contact 422 ', conductor 459, contact and 563, conductor 586, top coil winding 644, and battery. A hold circuit for relay 644 is closed at contact 646, by conductor 698, at 1a. earth at contact 667. At contacts 648 and 647, relay 644 opens part of the timer circuit. At contact 649, the earth is connected to conductor 727, through which the timer circuits are controlled.



   Suppose the communication is addressed from the. usual way at a subscriber station. The called subscriber, by answering,

  <Desc / Clms Page number 67>

 causes relay 676 to be excited by relay 700. Relay 676 interrupts the excitation circuit of timer relay 670, at contact 678; it opens on contact 679 the last part of the holding circuit of relay 670. Relay 670 drops out, and the timer can no longer intervene.



   Suppose that the communication is addressed in the usual way to the trunk group N 7, in which case the relays
 EMI67.1
 1200 and 1270 are energized, in response to the jnnnnnotation of the first digit 7. The previously mentioned earth applied to the conductor 727 by the contact 649 is extended through the contacts 1203 'and 1278, the conductor 1488, and the contact. 1458 to the chosen repeater, by driver 1444.



   A circuit is then closed for relay 1635, which eliminates the timer, as will be described in a following chapter.



  Special services offered to inter.
 EMI67.2
 



  --------------------------------------------------
Other trunk groups enjoy additional service facilities, in addition to service restrictions and timer disconnection. A description will now be given of how communications emanating from line circuit 206 and receiving a supervisory signal at 60 pulses / min, in addition to the usual busy signal, may ignore the state of. occupation and intervene in the link, while disconnecting the timer described above.



   The calling line is extended by the repeater to the connector, passing through the searcher in the usual way, due to the excitation of relays 500, 520, 540, 550 and 560 by relays 300 and 340 of the contact. 30I, relay 300 energizes relay 420 through conductor 396. Relay 420 at contact 427, in conjunction with relay 340, at contact 34I, energizes relay 930. Relay 930 establishes certain restrictions.

  <Desc / Clms Page number 68>

 of service, as we have. seen in the chapter correspond. At contact 936, relay 625 is energized from ground to conductor 698, by conductor 699 and its lower winding.



   A holding circuit for rela.is 625 is closed at contact 628, by earth at contact 698. At contact 627 ', relay 644 is energized, to deactivate the conversation timer in the connector and the repeater. , in a manner similar to that described above.



   Communication is established through the connector in the usual manner. Long distance communication corresponding to. a one-digit N is directed to one of the junctions of the numbered group, through the group access and junction selection equipment of Figures 12, 11, 13, and 14, in which the relay 1200 or relay 1300 are temporarily energized, to associate a repeater pre-selected by the junction selector relays. At contact 629 ', ground is connected to conductor 726, which is extended through the group access relays of Figures 12 or 13, for the purpose of a special junction marking pulse service, not applicable only to such calling lines.

   This marking impulse intervenes in the repeater which is seized, to give the interurban connections additional facilities of access to the junction circuits. In particular, the conductor 726 is extended by the contacts 1308 'and 1378 to the conductor 1379 and to the relay 1920, to allow the inter operator to number a suffix digit on the group of junctions N 8, while the numbering of this additional digit is not possible for other lines, as will be explained in the description of Figures 19 and 20 concerning the repeater.



   Suppose now that a local NI is formed, instead of an inter N, and that the local line is occupied by another

  <Desc / Clms Page number 69>

 local munication. We will describe how a communication emanating from a line whose inter relays 625 and 644 are energized, as described above, can ignore the busy state.



  In particular, the C line 270 will be called in the usual way, in which the relay I030 is energized after the second digit and the relays 1020 and 1000 after the third digit, closing a circuit of the conductors 1081 and 1082 to the calling line. . At the same time, a busy test circuit is prepared between relay 770 and conductor 1083, as described in chapter II Local communications'. A busy state of the called line is indicated by an earth to the I083 conductor, and therefore relay 770 is energized. A busy signal is returned to the calling line at contact 771 in the usual manner.

   At contact 772, in conjunction with energized relay 625, at contact 626, a circuit is closed for the lower winding of relay 620, through conductor 640 and hard: contact 791, to a pulse source earth, at 60 pulses per minute. Relay 620 follows the ground pulses, and current to the calling line is reversed at contacts 621-624 at the indicated rate. Junction circuits responding to battery reversals are well known and should not be described here. It is sufficient to know that the junction circuit, in response to the reversing currents, causes the monitoring lamp to flicker in the operator position. The attendant then receives a visual signal, in addition to the usual acoustic busy signal.



   The attendant can then make people wait on the busy line; it can either disconnect and release the link, in the usual way, or dial an additional digit, and ignore the busy state. This last possibility

  <Desc / Clms Page number 70>

 will now be described, based on the above, relays 1030, 102.0, 1000, 770, 62.5 and 644, as well as relays 610, 630 and 640 being energized. It was previously established that relay 710 attracts after dialing the bell digit, and that the pulse circuit, comprising contacts 634, 606 and 666, and conductor 693 leading to the counting relays, is transferred, by the contacts 715 and 627 to relay 790, by conductor 698, contacts 783 and 793 'and the battery in 790.



  In response to the additional pulse emitted on the circuit discussed previously, relay 790 is energized, and prepares an actuating circuit for relay 793, at contact 792. Relay 793 is shunted by the earth. 790 and is not actuated until the actuating pulse circuit of relay 790 is covered. Relay 793 is energized in series with relay 790, by ground to conductor 698, and. battery to relay 790 ,; relay 790 is maintained by the preceding circuit. "On contact 791, relay 790 opens the connection to the pulse source at 60 pulses / min, to stop the intermittent operation of relay 620.

   On contact 798, relay 793 opens the circuit for maintaining occupancy relay 770; this relay being timed tripping, it is kept energized, when contact 799 closes, by a circuit extending from the battery, by the winding of the occupancy relay 770, of the contacts 773 and 799, of the driver. 659, from contacts 1006, 1027 and 1059 to ground to conductor 1082, until the. called line becomes free. At contacts 795 and 797, relay 793 connects the conversation conductors 638 and 639 to the conversation conductors 637 and 652, to allow the calling operator to intervene in the local call established on line C 270.

   The attendant can then inform the called subscriber that a communication has been made, or she can make the caller wait until the local call is terminated.

  <Desc / Clms Page number 71>

 



   When local communication is complete, ground is disconnected from conductor 1083, with the result that the occupancy relay 770 drops out, to close a drive circuit for the switching relay 780, depending on the ground, contacts 607 and 668, the top coil of relay 780, contact 776, conductor 738, contact 925, conductor 659, contacts 1006, 1027 and 1059, conductor 1083, extending to the line circuit of the called subscriber, passing through the windings of the cut-off and closing relays, similar to relays 250 and 260, to the battery.

   At contact 786, relay 780 is maintained by its lower winding; it opens on contact 786 the circuit of the intervention relays 793 and 790, which drop; at contact 788, it closes the circuit allowing the actuation of the recovery relay 730, which closes at contact 731 the circuit for energizing the odd bell relay, 750, from the common call breaker. At contacts 755 and 753, relay 750 closes the circuit to ring the called line. In the uas where the attendant remained online, she hears the call return signal through the following circuit: the generator, the winding of the call cut relay 740, the capacitor D 4, the capacitors 751, 796 the driver 639 'and the operator position.



   When the called subscriber answers, the call cut relay '740 and the relay 700 are energized by the calling loop, and the connection is established, as previously described. In the case. now, however, the operation of the changeover relay 620 produces the operation of the well-known supervisory signal at the operator position ', to inform it that the called subscriber has answered.



  Repeater 1600.-
 EMI71.1
 nr ... r ...... r..r .... r .. r-r.n1 A description will now be given of the repeaters

  <Desc / Clms Page number 72>

 of the group of junctions "7", through which the communications are extended to an automatic center, in which is found. checkered table.



   For ease of description, it will be recognized that the communications emanating from trunk groups 9 and 0 (operator trunks) can be extended to terminating office subscribers, and that subscribers of this; office- only need to dial a single-digit number to reach the. inter- table via the trunk group 7. It is understood that the repeater of the central connection can be from. any type of automatic repeater, designed for monitoring by reverse current; however, for the. ease of description, reference will be made briefly to the repeater 1900 shown in FIGS. 19 and 20.



  Outgoing communications.



  The extension of a calling line, up to the repeater, through the finder and connector, in response to the numbering of the number 7, has been explained in a separate chapter.



  It suffices simply to recall that the line conductors 1087 and 1089 are closed, at the calling station, by the contact of the dialing disk. Conductor 1091 is connected to conductor 594, and a ground is applied thereto to maintain the connection; in addition, a ground is extended to the conductor 1444, 'during the period of establishment, only in the case where the communication emanates from certain junctions.



   The establishment of the connection with a subscriber will first be described in the case where the conductor 1444 is not earthed, so that the relay 1635 is not energized. Ground to conductor 1091 energizes relay 1630 through contact 1859 and conductor 1795. At contact 1632, relay 1630 disconnects earth from conductor 1443, which releases marking relay 1440. Vacancy of: the. junction to. relay. selectors, of junctions of: the .. fig. I4, of: so as to prevent any. other line.



   ..

  <Desc / Clms Page number 73>

 caller to enter, junction busy. At the same time, the. relays 1765 and 1760 are excited, in series with the. line of the calling station, by conductors 207 and 208. At contact-1766, relay 1765, prepares part of the circuit for: controlling the relay, line changeover 1600. At contact 1763, relay 1760 energizes the 1750 relay, by the.terre. in 1743. On contact 1752, relay 1750 energizes: relay 1755; it opens on contact 1751 the incomplete circuit of relay 1730, and on contact 1753 closes a holding earth multiplied on contact 1763. On contact 1757, relay 1765 prepares part of the circuit according to which. the $, relay 1750 is re-energized during the pulse period.

   On contact 1758, relays 1740 and 1850 are energized. At contacts 1859 and 1858, relay '' '1850 transfers conductor 1091 of relay 1630 to earth at contact 1612, in series with the winding, low resistance of impedance 1700. The circuit shown below above is there. source of earth for maintaining the connector relay 660, mentioned in the case of the connector calling the number 7. Relay 1630 drops out, but the guard circuit. es, t maintained in contact 1749, which. is open. On contact 1856, relay 1850 closes a multiple hold circuit for relay 1755.

   At contact 1855, a polarized winding of relay 1825 is energized, but this winding is not strong enough to actuate the contacts, unless the currents flowing through the two windings of the relay are additive. 1851-1854, the connecting conductors leading to the repeater of the remote exchange: are transferred from relay 1860 to relay 1825; they include, contacts, 1756, 1726 and 1731. The above junction ends in a relay corresponding to relay 2055, which is energized according to the above circuit.

   This circuit comprises: the earth to the remote repeater (relay 2055), the conductor 1899, the contact 1866, the winding of the translator 1845 ', the contact 1852, the winding of the relay 1825,

  <Desc / Clms Page number 74>

 the current limiting resistor 1825 ', the contact 1854, the lower winding of the translator 1845', the conductor 1895, the contacts 1731, 1726 and 1756, the conductor 1894, the contacts 1854 'and 1868, the conductor 1898 and the battery to the remote repeater (by winding relay 2055).



   The repeater is now ready to receive dialing pulses from the calling station. Relay 1760 drops out during each pulse opening period, to open at contact 1763 the circuit of relay 1750. Relay 1750 drops ;, and momentarily disconnects at contact 1752, one of the earths keeping relay 1755 activated, but this relay is triggered, and its armature remains attracted during the pulses. On contact 1751 ;, relay 1750 closes the excitation circuits of relays 1730 and 1830. The excitation circuit of the time-delayed release relay 1830 comprises earth, contacts 1751, 1723, 1712 and 1759, conductor 1884,1 winding of relay 1830 and battery.

   The 1730 relay drive circuit consists of ground, 1751, 1766, 1738, and 1728 contacts, 1730 relay, and battery. At contact 1734, relay 1730 closes a holding circuit for itself; it energizes on contact 1732 the relay 1725 and energizes on contact 1733 the relay 1735, by the earth at the contact 1751 and the contact 1746. The relay 1735 is maintained by the contact 1737 and the resistor 1739, independently of the contact 1733, and opens in 1738 the initial circuit for energizing relay 1730, which is maintained by its holding circuit until relay 1725 is energized.



    On contact 1731, relay 1730 opens the junction loop to the remote repeater, dropping relay 2055, and thus repeating a pulse. Relay 1725 is energized, and again opens, at contact 1726, the junction loop to the remote repeater. On contact 1728, relay 1725 opens the circuit of relay 1730, which drops out, and closes in 1727 a circuit for

  <Desc / Clms Page number 75>

 maintain the relay. 1755 attracted.

   The switching on and off characteristics of relay 1725 are modufated by variable resistor 1729, so as to produce a determined opening interval at contacts 1726 and 1731, whatever the variations of the pulse. received at contact 1751. It suffices simply for relay 1760 to drop long enough to allow aubrelais 1750 to drop when a reduced current flows through resistor 1755 '. Obviously, the 1750 relay cannot be re-energized before the 1760 relay.



   In addition, the re-energization of relay 1735 depends on the energization of relay 1730, to close contact 1733. Likewise, on relay
1760 is delayed when switching on, the repeated pulse is not affected, since the subsequent operation of relays 1730 and
1725 is blocked, by relay 1735 until contact 1751 is momentarily opened by relay 1760, energizing the relay
1750 after the 1735 relay is drawn. Relay 1830 being delayed when tripping is maintained between successive pulses, and shunt contact 1831 the upper coil of the relay
1825 and the resistor 1825, to facilitate the transmission of pulses to the remote repeater.



   At contact 1834, an excitation circuit for the relay
1650 is closed by earth at contact 1857, conductor 1883, contacts 1636, 1643 and 1666. At contact 1633, relay 1650 is maintained in series with relay 1660, earth at conductor 1885, at contact 1758 The 1660 relay driver circuit does not operate during the pulse series. With earth held at coil 1650. After the pulse series, relays 1760 and 1750 are re-energized; relay 1830 drops, and opens the shunt of relay 1660, which is energized. and transfers conductor 1883 from relay 1650 to relay 1640, at contacts 1665-1666.

   On contact 1651, relay 1650 disconnects conductor 1799 'from relay 1600, to deactivate the possibility of battery inversion of

  <Desc / Clms Page number 76>

 control, unless contacts 1638 are closed, as will be explained in the following, in the chapter concerning the communication established by an inter.



   Another reason to block the inversion of the calling line current, if only one digit is numbered in the repeater, is to avoid the need to insert a coin at the calling station with prepayment, in the case where such a set calls the attendant via repeater 1600.



   At contacts 1661-1664, relay 1660 prepares a circuit through which a well known category of service signals can be applied to the so called line as will be briefly described.



   Having energized relays 1650 and 1660 after the first digit, such communications can result in a manual table, such as a switch table.



   When responding to such communications at the manual table, the current is reversed on my called junction, in a well known fashion. The reverse current flowing through the upper winding of relay 1825 now helps the lower winding, instead of being in opposition, and relay 1825 closes contact 1826. Relay 1820 is drawn and extends to conductor 1822 a ground to conductor 1889 , energizing relay 1720, through contacts 1715 and 1662 and conductor 1796. At contacts 1721 and 1722, relay 1720 connects the upper winding of coil 1700, in series with capacitor 1701, to line conductors 1897 and 1896 .

   Coil 1700 acts as a transformer, and a category of service signals (alternating current of approximately 200 to 400 Hz) applied to conductor 594 at the calling line circuit is extended to conductor 1091, ground to contact 1612, through the lower winding of the coil 1700. This

  <Desc / Clms Page number 77>

 signal is transferred. by induction to. the operator, as: indicated above, .. The. contact 1724: is controlled by a blade of. res, - exit weighed down by a weight, which produces a vibration, so as not to: allow the. contact 1724 will effectively energize relay 1710 only after a slight delay, usually about a second.

   Relay 1710 is attracted after: this delay, and remains at conductor 1889, at contacts 1714 and 1664. Relay 1710 disconnects., At contacts 1712, 1713, on. circuit leading to relay 1830, and prepare the relay circuit. 1705. At contact 1715, relay 1710 opens. the relay excitation circuit, 1720. The relay 1720 drops out, and disconnects the coil 1700 from the line.



   The excitation circuit of relay 1705 is not closed until the calling subscriber hangs up. ,, closing contact 1751 again, de-energizing relays 1760 and 1750. In the event that the attendant does not switch off not, the current, Inverted is maintained on the anointing, as well as the, battery to the conductor 1899, extending to the conductor 1893. In this case, the relay 1705 attracts, and maintains at contact 1706 them. 1740 and 1850 relays energized, as well as all equipment. connected. The release of the connection is placed under the control of the attendant ...



   Having described the establishment of a communication via a junction to an intercom operator accessible from the calling center by dialing a one-digit name, let's go. now describe the operations that take place when a remote exchange subscriber is called. The operation is the same as that described above for the first digit, including the excitation of. I650 and 1660 relays. Subscriber numbers are made up of several digits.

   Therefore, at the start of the numbering of the. 2nd. cipher, the 1760 and I750 relays are restarted; the relay is energized again, by earth at contact 1751, closing an excitation circuit for the. redo 1640, by the.

  <Desc / Clms Page number 78>

 earth at contact 1857, contact 1834, conductor 1883, contacts 1636, 1643 and 1665. Relay 1640 maintains ground at conductor 1885. Contact 1642 opens, releasing relays 1660 and 1650. The first circuit mentioned for relay 1650 is open at contact 1643, and the reversing relay circuit 1600 is closed at contact 1651. When the called subscriber answers, the current is reversed on the junction line between the two exchanges. a well known way.

   The current in the upper winding of relay 1825 is now kept in the same direction as that of the lower winding, and both windings add their action, to energize relay 1825. Relay 1820 now energizes relay 1600, for example. earth, contacts 1822, 1819 and 1766, and conductor 1799 'At contacts 1601-1604, relay 1600 reverses current to the calling station.



   The repeater is released from the. well known way. In short, the calling subscriber hangs up, relays 1760, 1750, 1755, 1740, and 1850 drop, and earth is disconnected from conductor 1091 at contact 1858, which removes earth from conductor 594 and relay 660. The researcher and the researchers connector relays return to their rest position.



  Communication established by an inter operator.



  It can be deduced from the preceding description that the relay 1635 is energized when a communication is requested on a group of inter-junction, such as that of the central 200. A momentary earth is extended on the conductor 1444, and is only effective during the establishment period. Relay 1635 holds on. earth to conductor 1091. The operation of the repeater is the same as described previously, except that the circuit of relay 1600 is not open when that of relay 1650 is open at contact 1636. In addition, a multiple circuit to energize the relay 1600 is closed at contact 1638. Relay 1600 is therefore energized

  <Desc / Clms Page number 79>

 each time the called post answers ,, and the relay 1825 is energized by the reverse current referred to., through the junction line.



   On contact 1637, relay 1636 opens the circuit of relay 1620, to put the timer out of service -, as: explained in. what follows.



  Time limit for long distance calls.



  The repeater timing device, comprising the relays: 1620, 1610 and, 1630, works: in a similar way to the corresponding timer relays 670, 680 and 730. In short, circuits are prepared for them. . time control conductors 616, 618, 609, 619 and 617, by the timer pulse generator 760 ', in the following order: an earth pulse to conductor 616, an earth pulse to conductor 618 two minutes later, a ground pulse to conductor 609 a minute later.



  Conductors 619 and 617 are normally closed. The conductor 619 is open momentarily, before the. Earth- was connected to conductor 618. Conductor-617 is momentarily open before conductor 619 opens. The type of timer is well known, and will not be known. not described here. The duration of a pulse, as well as an opening period, is about one second.



   The conductors 616 and 618 intervene in the following manner to limit the duration. of a communication - remaining unanswered.



   The way that the. repeater is. know, i during an outgoing communication, including the excitation of the relay, 1740, has been described in the above, and will not be repeated. At contact 1745, conductor 616 is extended to conductors 1886 and 1887, leading to relay, 1620. At the appropriate time, a ground pulse is connected to conductor 616, energizing relay 1620.



  At contact 1623, the relay. 1623 remains at the. earth at conductor 1796, at contact 1821. At contact 1624, conductor 618 is:

  <Desc / Clms Page number 80>

 extended to the lower flow of relay 1610.



   About two minutes after actuation of relay 1620, relay 1610 is energized by timer conductor 618, provided that the call has not been answered. Relay 1610 is held by conductor 1885 to earth, through contact 1617. At contact 1612, relay 1610 disconnects the earth of conductors 1798, 1882 and 1091, through which the local searcher circuit -connector is maintained, with the result that this circuit is automatically released. If the call is answered within two minutes of the request, the current is reversed on the excitation relays 1825 and 1820. The contact
1821 is open, releasing relay 1620.

   At contact 1823, one of the circuits mentioned above, starting from conductor 616, is opened. However, the circuit from conductor 616 to relay 1620, through contacts 1637 and 1652, effectively re-energizes relay 1620, when conductor 616 is grounded again. Obviously, the last quoted drive circuitry of relay 1620 is put out of service either if the communication is a one-digit number, in which case relay 1650 remains in the attracted position, or if the communication is from. an interoperator, in which case relay 1635 is energized.

   Thus, the device making it possible to limit the duration of a communication is put out of service for numbers consisting of a digit, or for calls originating from an intercom operator.



     When the communication is answered, the 1825 relays,
1820 and 1710 are energized, and the 1710 relay puts the driver
1091 to earth at contact 1711, through contacts
1621, 1613 and conductors 1798 and 1882, to maintain the finder-connector circuit after energizing relay 1610.



   Relay 1610 is energized as described previously, and relay
1610 replaces contacts 1612 and 1613, earth in contact
1711 to earth at contact 1612. At contact 1615, the

  <Desc / Clms Page number 81>

 holding relay 1620 is transferred to the earth conductor 619 of the timer. Approximately two minutes after actuation of relay 1610, earth is removed from timer conductor 619 to release relay 1620. On contact 1622, relay 1620 provides a holding earth from timer conductor 617. location of contact 1711. Approximately two minutes after releasing relay 1620; The earth is disconnected from relay 617, thereby removing the holding earth, to release the finder-connector circuit and the repeater.

   Before the timer is released for this circuit, lead 609 is grounded, to operate :)? ' relay 1630. Relay 1630 closes at contact 1631 a circuit sending an acoustic signal to the conversation conductors, to warn the calling subscriber that automatic release will take place.



  Incoming communications.



  An incoming call is extended from the remote repeater to the subscriber line or another trunk in the usual way. In short, during restoration, a bridge comprising a polarized relay responding to the current pulses, which are repeated by these contacts.



   Relay 1860 is energized by the above circuit, and energizes relay 1840 at contact 1862. At contact 1843, relay 1840 opens the earth circuit of conductor 1443, to occupy this junction and the junction selector relays . Relay 1810 is energized by earth at contact 1841, and a bridge is connected to contacts 1811-1816, on conductors 207 and 208 leading to line circuit 205. This bridge has the top winding of relay 1825. , resistors 1813 'and I825' and the pulse repeater contact 1861.

   The circuit included the conductor 207, the contact IBII, the. translator 1845, contact 1813, resistance 1813 ', the flow of the coil 1825, the

  <Desc / Clms Page number 82>

 resistance 1825 ', the contact! 1816, the lower winding of the translator 1845, the contact 1814; the contact 1861, the conductor 208. It is understood that the line circuit 205 is the same as the line circuit 215, the conductors 207, 208 and 277 corresponding respectively to the conductors 217, 218 and 295.



  Closure of this bridge circuit energizes the line circuit relay which causes the extension of a connection circuit, via the finder contacts 504, 505 and 506. A multiple holding circuit is closed for relay 1810., by earth in contact with the line circuit relay and conductor 277.



   The relay 1860 responds to the dialing pulses, and repeats the corresponding pulses on contact 1861, to actuate the connector in the usual manner. Relay 1830 attracts on the first Pulse, bypassing the top winding of relay 1825 to contact 1831, to facilitate the transmission of pulses. Relays 1830 and 1840 remain attracted between successive pulses.



   When the line circuit was first seized, the line was marked for restricted service, in accordance with the operation of relay 930, and long distance service facilities, at relays 625 and 644. In short, the relay 930 is energized from earth at contact 331, by contact 426, conductor 457, contact 558, conductor 457 ', lower coil of relay 930 and the battery. Relay 930 energizes relay 925 at contact 936. At contact 627 ', relay 625 energizes relay 644. Relay 930 gives access to this terminal to contact 934, and prevents access to the group of junctions 8 at contact 933 .

   The purpose of energizing relays 625 and 644 to provide an override capability, special busy signal flickering, and special trunk service has been described.

  <Desc / Clms Page number 83>

 in the chapter on long distance service facilities, and will not be repeated.



  Group 8.- repeater
 EMI83.1
 ---------------------
A description will now be given of a type of automatic central repeater characterized by a service restriction allowing it to repeat only a fixed number of digits (4), unless the call is not made. emanates from a determined group of junctions. In the latter case, marks are extended to the repeater, to identify the communications coming from certain junctions, which disable the restrictive characteristics of digits, and allow the repetition of an unlimited number of digits.



  Outgoing communications. - --------------------------
The seizure of the repeater by the calling station which dials the number 8 was described in the previous chapter, "Grouping of trunks 8".



   Similarly, the 2000 and 2005 relays are energized in series. with the calling line, which is extended through the searcher and connector. These are maintained by the repeater, which extends a holding earth circuit, to contact 2046, for conductor 1076. The holding circuit can be traced as follows. Relay 2000, at contact 2003, energizes relay 1985 ', by earth at contact 1972. At contact 1988', a multiplied earth, via resistor 1989 ', is connected to it to maintain relay 1985 'after the energization of relay 1970. Earth at contact I987' energizes relay 1980. Earth at contact I98I energizes relays 1970 and 2040 via conductor 2091.

   At contact 2046 ', the relay 2040 extends a tere

  <Desc / Clms Page number 84>

 from contact 1952, by driver 1991, to driver 1076, to keep the previous switch in the pulled position.



  At contacts 2041-2046, relay 2040 transfers junction conductors 2099 and 2098 from earth and battery to coil 2055, to a bridge holding circuit comprising contact 2042, the top winding of coil 2025, resistor 2028, contact 2044, lower coil 2070, conductor 1993, contacts 1985, 1969 'and 1968, conductor 1992, and contacts 2046 and 2063. The currents flowing through the upper and lower windings of coil 2025 are in opposite directions; relay 2025 is adjusted so as to actuate contact 2026 only when the currents {Without the two windings of the. coil 2025 are consistent.

   The jonstion conductors terminate at a repeater located in the automatic sub-office, in which the battery and earth, through a relay similar to 2055, are connected to the line. This relay responds to pulses repeated dialing, to control the extension of the call to the called station. When the call is answered, the current is reversed on the connecting conductors.



   Having energized relays 2000, 2005, 1985 ', 1980, 1970, and 2040 upon setup, the repeater now responds to the next series of dial pulses. Relay 2000, in response to the dial pulses, opens and closes the 2001-2003 contacts. At contact 2001, a circuit is prepared to re-energize relay 2000, via the limiting resistor 2004. This does not allow sufficient current to flow to energize relay 2000, until the line loop is closed. closed by the contact of the numbering disc. On contact 2002, a circuit is closed to keep relay 1980 energized.

   Relay 1985 'drops out, due to the opening of the contact

  <Desc / Clms Page number 85>

   2003, and energizes on contact 1986 'ke relay 1965', by contacts 1983, 19861982 and 1966. On contact 1966 ', the relay 1965' closes its own holding circuit. On contact 1969 ', the bridge on the anointing conductors is opened, causing the line relay of the junction to drop again, to repeat an opening period corresponding to the terminal devices. On contact 1967 ′, the 1985 relay is energized; it closes its hold circuit on contact 1987. On contact 1986, the excitation circuit of the relay 1965 'mentioned first is opened.

   Relay 1985 prepares at contact 1988, in conjunction with closed contact 1973, a ground circuit through which relay 1985 'is re-energized, after contact 2003 has closed. At contact 1968 ', the 1965 relay energizes the 1965 relay. At contact 1968, the junction loop is opened again. On contact 1966, relay 19654 drops out, and opens contact 1968 ', causing the 1965 relay to be reworked. Relays 1965 and I965' close the junction loop, completing a pulse. The following pulses are repeated in an analogous manner. It is evident from the preceding description that the duration of the repeated pulses is independent of the pulses received at relay 2000.

   All that is required is for the relay to open and close for a time sufficient to energize or release relay 1985 ', as well as relay 1985. The duration of the repeated pulses is controlled by the pulling characteristics. and triggering of relays 1965 and 1965 '. These characteristics can be changed by adjusting the 1959 shunt resistance.



   A feature of the repeater is to limit the number of digits that can be repeated for communications subject to the restriction. When relay I985 'drops out, a circuit is closed by contacts 1986' and 1983 and conductor 2093 to energize relay 1030. At contact 2033, earth in 1971 by the

  <Desc / Clms Page number 86>

 conductor 2090 is extended to relay 1925, by conductor 1996, contacts 1921, 1926, 1931, 1931 'and 1941. Relays 1925 to 1940 are two-stroke relays, in which the upper winding alone is Powerful enough to close a contact group. Relay 1925 only closes contact 1928, extending the lower winding to ground at contact 2047, through contacts 1934, 1937, 1943 and conductor 1995.



  The lower winding is shunted during the pulses, the relay 2030 remaining attracted between the successive pulses. Relay 2030 falls back into the interval between two digits; it disconnects the earth of the 1996 conductor, and the 1925 relay with its two windings acting, extends the 1996 conductor to the 1930 relay, at the 1927 contact. Similarly, the 2030 relay is re-energized during the following series of pulses, and relay 1930 closes contact 1933. Relay 1930 is fully energized after relay 2030 has de-energized again. Relay 1925 drops out when contact 1934 opens, to extend conductor 1996 to relay 1935, through contacts 1921, D926 and 1932.

   Similarly, relays 1935 and 1940 are energized for successive digits. At contact 1944, contacts 1968 and 1969 'are bypassed and subsequent pulses can no longer be repeated at contacts 1968 and 1969'.



   The feature described above, allowing to limit the number of repeated digits is not used in cases where the communication emanates from a group of inter junctions, in which case an earth is extended to the conductor 1379 during the period of establishment. The means used to emit the said earth on the 1379 conductor are similar to those described in the case of a communication emanating from groups 0 or 9, as mentioned in the case of calling the group of junctions 8. The relay 1920 is energized via conductor 1379, and closes

  <Desc / Clms Page number 87>

 its contact holding circuit 1922, by ground to conductor 1076 and the battery to the lower winding of coil 1920.

   At contact 1921, the circuit of relays 1925,1940 is disconnected.



   When the communication is answered, the current is reversed on the junction conductors 2099 and 2098. The currents in the two windings of the relay 2025 are in the same direction; contact 2025 closes, and energizes relay 2020. Ground at contact 202I energizes relay I905 through conductor 2099 and contact 2006. At contact I908, relay I905 closes a multiple circuit for the contact. 2006, thus preventing the calling subscriber from releasing relay 2025. At contacts I906 and 1907 ', the circuit of the calling line is reversed, for monitoring purposes.

   The purpose of passing the excitation circuit of relay 1205 through contact 2006 is to prevent the reversal of current on a grounded line, in which the relay 200 is energized by a grounded conductor, and the relay 2000 is not energized.



  The operation of the line to earth is well known and is not described here. Obviously, any abnormal condition, such as earth to conductor 1074, would prevent relay 2005 from energizing, thereby effectively blocking current reversal and preventing simulated release of the connected equipment.



   The relay I9I5 is energized in multiple with the relay 1905, the purpose of which will be explained in what follows.



  Measurement of the duration of a communication
The timer pulses are extended from the common timer 760 'on conductors 609, 617, 618, 619 and 616.



   For ease of explanation, it will be assumed that the entire timer period has 4 cycles of two minutes each.



   It is understood that conductors 616, 618 and 609

  <Desc / Clms Page number 88>

 are normally open, and conductors 617 and 619 are normally closed.



   The excitation of the 1970 relay when the repeater is seized has been described previously. On contact 1975, conductor 616 is extended to relay 1960, through contacts 1912 and 1957. During the first cycle of a period of time :, conductor 616 is momentarily raised to. earth, thereby energizing relay 1960, which remains earthed at contact 2047, through contacts 1964, 1955 and 1974, conductor 2088, contacts 2032, 2022 and 2047. This circuit can be inserted terminated at contact 2032 for each series of pulses received, or at contact 2022, when the communication is answered. On contact 1963, relay 1960 extends conductor 618 to relay 1950.

   In the next cycle, conductor 618 is momentarily grounded, energizing relay 1950, provided the holding circuit described above for relay 1960 is not opened due to dialing or response. before the 1950 relay was energized. At contacts 1952 and 1953, relay 1950 disconnects the earth of the 1991 conductor. It is recalled that the earth of the 1991 conductor has been transmitted to the 1076 conductor, to maintain the finder and the connector; therefore it is evident that the finder scope and the connector fall back, and that the. calling line is unlocked at the line circuit in a well known fashion.



   A description will now be given of how the duration of a conversation is counted, and how it is released after a period of about 8 minutes. It is obvious, in this case, that the communication is answered before the relay 1950 is energized. Furthermore; when the response relay 2025 attracts, the relay 2020 is energized, to produce the excitation of the relay 1915, at contact 2021. At contact 1918, relay 1915 closes a circuit which maintains itself to earth at contact 1971, before

  <Desc / Clms Page number 89>

 that contact 1917 opens. At contact 1916 an earth is extended at contact 1962 '. During the following two-minute interval, the I960 relay is re-energized via the contacts.
1975, 1912 and 1957.

   During the following two-minute interval, relay 1950 is energized by earth at conductor 618. At contact 1952, conductor 1991 is transferred to earth at contact.
1916, and the 1960 relay is transferred to contact 1956 to a ground at conductor 619, controlled by the timer. For the next two minutes, conductor 619 is momentarily open, releasing relay I960. At contact 1962 ', the 1991 conductor is transferred to earth to conductor 617. At contacts 1951 and 1961, conductor 609 is extended to relay 1945. During the following minute, the timer extends an earth pulse to conductor 609 energizing the relay 1945.

   At contact 1947, an acoustic signal to conductor 797 is extended to the calling line, connected to conductor 1075, by contact 1959, conductor 1948 and conductor 1994. This signal is used to warn the subscriber that the communication is - tion will be cut in a minute. During the next minute, the timer disconnects the earth of the conductor 617, which is the holding earth of the finder and connector. The switches are therefore released, and the line is released in the line circuit, as is well known. During the period of opening to conductor 617, conductor 609 is again closed. land, and the 1945 relay is drawn.

   The signal is transmitted again on the calling line, during the release period, and the junction is kept at the open contact 1946.



  Incoming communications. - --------------------------
The way in which an incoming call is established is similar to the case of communications by other repeaters.

  <Desc / Clms Page number 90>

 



  Therefore, the description will be given briefly. The communication is extended from the calling station of the remote exchange to a terminal repeater. The latter extends during its intervention a pulse repeater bridge on conductors 2099 and 2098, which energizes relay 2055. The earth at contact 2057 energizes relay 2035, which energizes 2010 at contact 2037. Relay 2010 extends a bridge pulse repeater on conductors 217 and 218, leading to line circuit 215. This is the same as line circuit 210, so the line relay is energized and controls the finder, to extend the above conductor up to a connector.

   The connector line relay is then energized by the following circuit: earth, the upper winding of relay 610 ,. conductors 508 and 217, contact 2011, the top winding of the translator 2070 ', the contact 2013, the resistor 2029, the top winding of the relay 2026, the resistor 2028, the contact 2015, the bottom winding of the translator 2070 ', contacts 2016 and 2056, conductor 218, conductor 509, lower coil of relay 610 and the battery. Relay 2055 responds to dial pulses, which are repeated to relay 610 by contact 2056.

   Relay 610, in response to said pulses, extends the connection in a well-known fashion. Relay 2025 does not close contact 2026 as long as the currents in the two windings are in the same direction. Therefore, when the called station answers, the current is reversed on conductors 217 and 218, at relay 620, and relay 2025 energizes relay 2020 at contact 2026. At contact 2021, relay 2020 cuts off the switch. earth to contact 2017 to relay 2060, via contact 2019.

   Relay 2060, is energized, and at contacts 2061-2064 inverts the current on conductors 2099 and 2098, causing a relay to operate in the repeater of the remote exchange.

  <Desc / Clms Page number 91>

 corresponding to 2025, to reverse the current on the calling set.



   A communication established with a local termination can. be released when the calling subscriber hangs up, releasing relay 2055, which opens the bridge at contact 2056, and drops relay 2035. The connector is released, in a well-known manner, and disconnects the earth of the conductor 295 . The. relay 2010 falls, freeing the repeater.



   It is evident from the foregoing description that during an extended communication on another repeater, the earth of the conductor 295 is not disconnected until the called operation has cut. Communication is therefore maintained until the two subscribers hang up, which makes it possible to use the current reversal for monitoring purposes or possibly for a callback.



  Automatic-manual repeater - -------------------------------
The manual central office junction circuit 290 can be of any of the many known types. It suffices simply to know that the control on the connection junction is carried out on a single-wire circuit, and is usually applied either in simplex or in composite (as in Morse telegraph) to the conductor of the junction.



   To facilitate the explanation, we will take the case of the simplex, in which the signals are extended on the two conductors in parallel. The manual junction circuit connected to the control conductor mentioned above is used for the call to the input transmission of dial pulses and to perform the supervisory checks.



    Incoming communications. - --------------------------
When the attendant requests a communication on the

  <Desc / Clms Page number 92>

 operators 2398 and 2397, relay 2330 is energized, in .-., series with the operator's dialing circuit, when the. junction is entered at the center. 290. At contact 2332, relay 2330 energizes relay 2310; on contact 2333, it closes the line relay excitation circuit of line circuit 211.

   This circuit involves earth to. line relay winding (not shown), conductor 212, contact 2329, top winding of translator 2393, contact 2325, top winding of relay 2355, resistor 2354, bottom winding of trans - generator 2393, contacts 2'326 ', 2333 and 2328, conductor 213 and the battery to the line relay (not shown). Line circuit line relay operation causes the finder to select line circuit 211, and connect the connector to the calling junction, in a manner analogous to that already described.



  When the junction is extended to the connector, the line relay 610 of the connector is substituted for the line relay of the line circuit. At contact 2312, relay 2310 closes a circuit passing through the lower polarized winding of relay 2355, through contact to earth 2323.



   At contact 2311, relay 2310 opens the hold circuit of distributor relay 2350e, causing relay 2350 'to drop when the distribution relays pull, to preselect another trunk line circuit, in a manner which will be described below. -after.



   The current in the upper winding of relay 2355 flows in the opposite direction to the current in the lower winding, and relay 2355 is not energized, as long as the two currents oppose each other.



   In response to the dial pulses, relay 2330 repeats corresponding pulses, at contact 2333, to line relay 610 of the connector, to make the desired connection.

  <Desc / Clms Page number 93>

 



  During the dialing period, relay 2340 is energized at contacts 2331 and 2314; being timed release, it remains attracted between pulses. At contact 2341, relay 2355 and resistor 2354 are bypassed, to improve the transmission of the pulses. Relay 2340 drops out in the interval between the numbering of the different digits.



   When the call is answered, the current to leads 212-213 is reversed, in a well known manner. The current in both windings of relay 2355 then becomes the same direction, and relay 2355 is drawn. Relay 2355 energizes relay 2350 at contact 2356. At contact 2352, the winding less than. Large resistance of coil 2330 is added to the upper winding of the simplex control circuit. This increase in resistance of the control circuit involves the manual control panel monitoring equipment, which indicates that the communication has been answered. When the called subscriber hangs up, the current is reversed again, releasing relays 2355 and 2350.

   The simplex control circuit is transferred to the low resistance top winding of relay 2330, and the end of conversion supervisory signal is energized at manual table 290. The operator cuts, releasing relay 2330, followed by relay 2310, and the connected equipment is released.



   Before describing an outgoing communication, emanating from conductors 1092 and 1093, through conductors 2398 and 2397, a description will be given of how the trunk line shown in Figure 23 is preselected to be connected with the dial-up repeater. return shown in fig.



  22, by equipping the distributor relay. This equipment is similar to the dispenser of Figure 4; it is well known that it suffices simply to review it briefly. Each junction occupied opens the circuit of a corresponding distributor relay,

  <Desc / Clms Page number 94>

 such as at contacts 2311 or 2322, to open the circuit to 2350-le which drops if energized and cannot be re-energized as long as the contacts mentioned above are closed.



   When all relays similar to relays 2350 'and 2370' are at rest, a chain circuit is closed and energizes relay 2340 '. At contact 2342', a ground is extended to relays 2350'-2370 ', via circuits comprising contacts such as 2311 and 2322. Each relay corresponding to a free junction is energized and holds to earth, respectively at contacts 2355'-2375 '. The circuit chained through contacts 2371-2351 is open, and relay 2340 'drops out. Relay 2330' is delayed on tripping and does not drop out during the. rest period described above. However, if all the junctions are occupied, relay 2340 'does not drop, and relay 2330' drops.

   At contact 2331 ', ground is extended to conductor 2287, which leads to a busy relay, such as relay 2250, of the previous junction equipment, as will be described in the following. Likewise, relay 2300 'is energized when the chosen junction is extended, and opens the circuit of relay 2310'. The latter is delayed on triggering and remains attracted for the normal duration of connection establishment.

   If this, however% is not established within the time determined in advance, relay 2310 'drops out, and closes a shunt circuit, through the battery, resistor 2392, contacts 2302', 2311 ', 2343', 2553 '' contacts 2322 and 2311, up to the winding of relay 2350 'and the battery. Relay 2350 'then drops out, and the next trunk line is preselected by the next distributor relay, such as relay 2370'.



  Outgoing communications.- --------------------------
Suppose now that the communication is extended by

  <Desc / Clms Page number 95>

 the finder-connector circuit and that the connector has established a link between the calling line and the terminals 1092, 1093 and 1094 of the repeater 2100. The relays 2140 and 2145 are energized by the conductors 1082 and 1093, the contacts 2134 and 2132 and the left winding of the translator in series with the calling line. Relay 2115 is energized by earth at contact 2142.



  Relay 2200 is energized by earth at contact 2118. Wing relays and 2200 extend contact earth to contacts 2117 and 2203. 2123 and 2264 ,: to conductor 1094, by which the connected circuits of the finder and connector are maintained. Relay 2110 is energized by the above circuit. At contact 2111, the earth is disconnected from the guard conductor 2112, to release relay 1160, which occupies the junction with respect to the selection relays described in figure 11, At contact 2119, an acoustic signal in alternating current, such as for example, a ringing current passing through the capacitor 2280 ′ ,. is sent on the calling line, to indicate that the communication is extended.



  Earth at contact 2202 energizes relay 2220 through contact 2211, contact chain 2279-2279 ", contact 2252, relay 2220, contact 2222, contact 2301 ', contact chain 2221 '-2221, and battery resistor 2229. At contact 2223, relay 2220 holds on to the battery, before the chain circuit is open at contacts 2221 and 2222. At contacts 2226-2227, relay 2220 extends each of relays 2270-2270 'to a corresponding distribution relay 2350'- 2370'. Only one circuit is closed by the distributor relays.



  Thus, the relay 2270 is energized according to the earth at contact 2356 ', by the conductor 2288', and remains earthed at contact 2274 ', by the contact 2202. The earth at contact 2373' energizes the relay 2320 by the ' intermediate conductor 2291. At contacts 2326 to 2329, relay 2320 disconnects the input line circuit, and closes the transmission circuit between the calling line and

  <Desc / Clms Page number 96>

 the junction leading to the remote exchange, via the translator 2394. The earth at contact 2324 energizes relay 2370 which opens the incomplete circuit of relay 2080 at contact 2371, and energizes relay 2360 at contact 2372. Relay 2360 opens the contact 2361, and relay 2370 drops out. Relay 2360 is maintained by contacts 2373, 2382, 2362 and 2324.

   Relay 2360 transfers to contacts 2365-2364 the simplex control circuit from relay 2330 to the inrush generator, to conductor 2395, which causes the. junction signaling lamp, in a well known manner. Relay 2350 is then energized by ground at contact 2232, conductor 2185, contact 2141, conductor 2184, contact 2271 ', conductor 2293, contact 2363, relay 2350 and the battery. Relay 2380 is energized after a slight delay, which includes the timing of relay 2370.

   Relay 2380 disconnects at contact 2385 the generator, and connects direct current to the control circuit, through resistor 2389, to eliminate residual foreign voltages which remain on the junction.



  The circuit of relay 2350 is held at contact 2383. Relay 2380 opens contact 2382, and relay 2360 drops out, closing the control circuit of relay 2330, which then includes the high resistance lower winding of relay 2330, since contact 2352 is closed and contact 2351 open, for monitoring purposes.



   When the attendant answers, the operations involved are similar to those described in the case of an incoming call. Relay 2330 energizes relay 2310 at contact 2332, and prepares at contact 2333 an incomplete pulse repetition circuit. At contact 2313, relay 2310 connects earth to contact 2324, to energize the relay which closes a well-known acoustic signaling circuit at contact 2258., on conversation conductors 2299 and 2292.

   In short, this circuit

  <Desc / Clms Page number 97>

 has capacitor 2259 ', contacts 2258 and 2257 and the in? lower bearing of coil 2259. Thus, any signal emitted on conductor 1094 is extended to the upper coil of coil 2259, and is inductively coupled to the junction for an interval of a specified time, controlled by the delay. brought to the energization of relay 2300 by the heavy contact 2256. After a certain time the relay 2300 is energized, by the contacts 2356 and 2301, to release the relay 2255 and disconnect the signal from the junction. At contact 2315, relay 2310 energizes relay 2260, via conductor 2295 and contact 2275.



  Ground at contact 2267 energizes relay 2160, which disconnects the waiting signal from the calling line, at contact 2162. At contact 2268, a multiple-circuit to ground is closed for relay 2200. At contact 2261, relay 2120 is disconnected from the timer circuit. At contact 2263, a multiplied holding circuit is closed for relays 2270 and 2320. At contact 2264, the shunt of the upper winding of coil 2259 is removed, allowing this coil to act as a transformer for the signal current. , as described in the previous chapter.



   Obviously, we deduce from the foregoing that the transmission circuit between the calling station and the remote operator is closed via translator 2393, and that the windings of translator 2170, as well as the power coils 2140 and 2145 of the calling station are connected to the calling line.



   In addition, the release of the link is controlled by relay 2200, which is controlled by the calling station, by relays 2I40 and 2115, and by the attendant, by relays 2330,23IO and 2260. If the The calling subscriber hangs up, relay 2140 opens on contact 2141 the circuit of relay 2350, which drops out, to warn the operator, by substituting the low-resistance upper winding of relay 2330 for the lower high-resistance winding .

  <Desc / Clms Page number 98>

 



  Return numbering.- ------------------------; to be given
A description will now go on how the operator being called can establish communication with another station, by sending dial pulses on the same trunk, on which the communication described above was established.



   The attendant connects her dial disk to the simplex control circuit of junction conductors 2398 and 2397, in a well-known manner, and numbers the digit 1. Relay 2330 drops, in response to the dial pulse, and at contact 2331 energizes relay 2340. At contacts 2344 and 2345, relay 2340 opens the high resistance winding through circuit and closes the pulse circuit via the low resistance upper winding, during the period d. 'impulse. When re-energizing relay 2330, after the first pulse, relay 2330 closes a circuit through contacts 2332, 2345 'and 2394', conductor 2294, contacts 2276 and 2235, for relay 2230.

   At contact 2346, relay 2340 energizes relay 2155 via contacts 2274 and 2214, relay 2230 holds on. the. earth at contact 2204, before contact 2235 opens; it opens on contact 2232 the circuit of relay 2350, which drops and extends to contacts 2236 and 2237 the conductors 275 and 276, leading to the line circuit, up to contacts 2333, and involves a searcher, who there extends a connector.

   This last circuit comprises the battery to the conductor 276, from the line relay, the contacts 2236 and 2273, the conductor 2297, the contacts 2327, 2333 and 2328 ', the conductor 2298, the contacts 2272 and 2156, the resistor 2174, conductor 2198, contact 2237 and conductor 275, earth to the line relay. On contact 2352, relay 2350 opens the circuit of the high resistance winding

  <Desc / Clms Page number 99>

 of relay 2330; it substitutes, for the contact 235, the upper winding with low resistance, so as to send a signal to the operator, through the simplex control circuit to notify her that the connection has been established through the circuit - repeater line fired.

   When the associated finder reaches this line circuit, and connects the corresponding connector of the local connection circuit, the attendant receives the connector numbering signal, in the usual way, and continues to number the digits of the number of the desired subscriber. Contact 2333 opens and closes, following the following numbering pulses, and communication is extended through the connector, in the usual manner. When the call is answered, current is reversed across conductors 275 and 276.



  The delayed tripping relays 2310 and 2340 are maintained between successive pulses, the relay 2340 falling between the different digits. Relay 2155, controlled by relay 2340, also falls between the digits; it opens at contact 2156 the shunt of the upper winding of relay 2240, and reconnects the transmission circuit to contact 2157. The latter is open during the emission of the pulses, to prevent them from producing unpleasant clicks. for the calling subscriber.



  The currents flowing through the upper and lower windings of relay 2240 oppose each other until the current is reversed, during the response; the two windings then combine and relay 2240 attracts. Relay 2240 energizes relay 2210, at contact 2243. Relay 2210, at contact 2215, together with contact 2143, closes a multiple circuit with contact 2333, for the connection established on conductors 275 and 276. At contact 2216, relay 2210 extends conductor 2283 to the top winding of relay 2200. Thus, ground to conductor 2283, coming from the established connection, holds relay 2200 until the link is released.

  <Desc / Clms Page number 100>

 



  At contact 2212, the rela.is 2210 closes a citcuit to re-attract the relay 2350, from the earth, via the contacts 2333, 2212, 2141, 2271 'and 2383 and the. battery to relay 2350. Relay 2350 again substitutes the high resistance winding of relay 2330 for the low resistance winding, thereby producing the operation of a supervision signal, announcing that the called aboone replied. Obviously, the attendant can either stay on the line or cut and release the junction. Suppose the operator cuts. Relay 2330 drops out and opens contact 2332. Relay 2310 drops out and opens contact 2315. Relay 2260 drops out and opens the circuit of relays 2270 and 2320.

   The equipment of fig. 23, as well as relays 2270 and 2255net coil 2259 are now free and can be used to establish other communications.



   The communication established between the calling subscriber and the called subscriber may be cut off when the calling subscriber hangs up.



  Relay 2140 opens the holding bridge at contact 2143. Relay 2115 drops out, together with the holding relay in the connector. Relay 2220 drops out, and opens earth to conductor 1094, which releases the connection of the calling subscriber. It is obvious that a ground to the conductor 2283 maintains the connection to the relay 2200. This last condition only exists if the communication is established through another group of junctions, which maintains the said conductor to the ground. until the subscriber hangs up.



   In the case where the repeater 2100 is seized by the local connector, and this one has been actuated previously by an interurban junction, instead of a local subscriber, the interurban relay 644 is then actuated, and, as previously described, relay 2150 is actuated.



   The 2150 relay actuation circuit is as follows:

  <Desc / Clms Page number 101>

 earth at the connector, contact 649, conductor 727 of cable 1290, contacts 1203 'and 1268, conductor 1291 of cable 1234, contact 1172 of the junction selector relay- 1169, conductor 2113 and l upper winding of relay 2150, in repeater 2100. At contact 2152, relay 2150 is held by conductor 1094 to earth; it prepares the 2130 reversing relay circuit for contact 2151, so that the contacts
2262 or 2242 close the actuation circuit of relay 2130, by contacts 2151 and 2142, when Empress answers, or when the subscriber answers, in the case of a call back to dialing.

   Contact 2132 bypasses contact 2142 and inverts the bateBrie to contacts 2132 to 2135, to warn the call operator, via the conductors.
1092 and 1093, that a response is given to the communication.



   Timed release.



   The repeater 2100 and the. local circuits are automatically released, in the event that the operator does not answer, within a determined time, or in the event that the subscriber called through the dial repeater returned by the operator does not answer after the attendant disconnects. This delayed release circuit is controlled by the relay 2120, which is in turn controlled by the common timer 760 '.

   The relay circuit 2120 extends from conductor 616 of the timer, through contact 2121, conductor 2181, contact 2241 (which is closed, provided that the called subscriber has not answered), contact 2261, which is closed (provided that the attendant has not answered, or has disconnected) contact 2201, conductor 2182, relay 2120 and the battery). '
When the conductor 616, is put. the earth by the timer, after. actuation of relay 2200, the circuit shown above is only closed if contacts 2241 and 2251 are closed.

   Relay
2120 maintains contact 2122, independently of the driver
798, for contacts 2123 and 2124, it substitutes the earth conductor 617 of the timer, for the earth at contact 2123, to maintain the

  <Desc / Clms Page number 102>

 connection established through conductor 1094. Relay 2120 drops if the attendant answers, or if the called subscriber answers, but if relay 2120 is kept attracted for a determined time, the earth is then disconnected from conductor 617 of the timer, with the result that it is also disconnected from the conductor 1094, to release the relay 660 from the connector, to produce the release of the connection, as previously described.



  Checking faults .-
FIG. 24 diagrammatically represents part of the equipment for fault control, verification and transmission of alarm signals, the purpose of which is to allow the monitoring of a telephone exchange without personnel, except for - firing of a manual exchange with direct traffic associated with it.



  It registers faults that occur in the control panel, and transmits alarm signals to the direct traffic office. The fault control equipment is entered by dialing the test number, in this case 1120011, plus any another ringing digit that may have been reserved for this purpose. The connectors are arranged so that it is only an operator or another authorized person of the direct traffic exchange who can dial in this equipment. The circuit is arranged so that more than one test, or a series of successive tests, can be performed in a single communication with the fault monitoring relays.

   To do this, we first do the test that we want to be performed first; the next test you want can be performed by numbering another digit, which is the difference between the number assigned to the test in question and the one just performed. "1" in the equipment, all tests

  <Desc / Clms Page number 103>

 and all operations can be performed successively.



   For the description of the fault check circuits, it will be assumed that the operator of the exchange 16 requests an incoming communication via the repeater I600 then numbers the fault check number "200", plus a digit of alarm. In response to this call, the repeater, finder, and connector operate, in the same manner as previously described. It should be remembered that during an incoming communication via the repeater 1600, the line circuit 205 causes the operation of the relays 300 and 330, which actuate the restriction relays 420 and 980 at their killers.



  This last relay 'prepares circuits to control interlocking relays 625 and 644, which allow the calling operator to obtain certain communications refused to other calling lines'. Briefly summarized, the connector, in response to the first digit "2", causes the actuation of relay 860, which is maintained, in series with relay 910; in response to the second digit "0", the tens relay 1040 is energized via the closed contact 934 of the relay 930, and maintains itself in series with the relay 900, as previously described. In response to the third digit "0" the 1000 and 2020 unit relays attract, and the. relay I020 is maintained, in series with the transfer relay of the third digit, 920.

   The circuit between the calling operator and the fault control circuit is then closed, via the closed contacts of relays 1000 and 1020 and 1040, and conductors 1095, I096 1097 and I098 terminating the control circuits of defaults. Test relay 780 is then energized by earth, contacts 607 and 668, conductor 696, the top winding of relay 780, contact 776, conductor 738, contact 925, conductor 659, contacts 1006, 1027 and 1066, conductor 1097, coil of relay 2410 and battery.

  <Desc / Clms Page number 104>

 



  Relay 780 operates, and is maintained; it connects, at contacts 781 and 782, the upper and lower windings of the relay 700 to the conductors 637 and 652, and therefore to the conductors 1095 and 1096 of the fault control circuit. At contact 2404, relay 2400 closes a bridge, on conductors 1095 and 1096, thereby energizing relay 700. At contact 701, relay 700 energizes relay 620, which reverses the current to the calling operator, to inform him that the fault control circuit has been entered. In response to the 4th. digit, which can be any ring digit, relay 710 is energized, as previously described.

   At contact 713, relay 710 energizes record release relay 690, through ground conductor 655, any of actuated contacts 814, 824 or 834, conductor 729, contacts 713 and 703, con. - driver 706, the lower winding of the relay 690 and the. drums.



  On contact 715, relay 710 prepares an impulse circuit, to allow Empress to activate the fault control relays. Relay 690 releases the pulse counter relays, as previously described.



   When the relay 930 is actuated and closes its contact 936, the switch relay 625 is energized by the earth conductor 698, through the conductor 699? Relay 625 is drawn, and holds on to conductor 698; it prepares at 627 another point of the pulse circuit of the fault control relays.



   When fault control equipment is grasped, through the connector, relay 2410 is actuated through conductor 1097, to prepare the pulse circuit for contact 2412; on contact 2414 it activates relay 2478, which transfers to contact 2479 the fault reset maintenance circuit of generator 2480 to earth at contact 2414. The relay

  <Desc / Clms Page number 105>

 2400 is also excited by conductors 1095 and 1096; in series with relay 700, when the fault control equipment is seized. On contact 2401, relay 2400 energizes the delayed on relay. 2402, which is maintained by contact,;.



  2407 to the conductor on the ground 1097. At contact 2404, relay 2402 opens the circuit of relay 2400, and relay 700, which drop. At contact 2401, relay 2400 energizes the time-delayed on relay 2402, which remains at the earth conductor 1097, by contact 2403. At contact 2404, relay 2402 opens the circuit of relay 2400 and relay 700, that fall back.



  At contact 2415, relay 2410 closes a circuit to intermittently actuate relay 2442, through conductor TP3, which is intermittently connected to earth, through the common timer, at intervals of approximately 4 seconds.



   When fault control equipment is entered, the dial signal and busy signal are intermittently connected to the calling line, to indicate to the attendant that the signal equipment is working, and that the dialing can take place. This circuit includes the dial and busy signal conductors DT and BT, contacts 2444 or 2443, contacts 2441, 2439 and 2437, to line conductor 1096, and from there, back, through the 'intermediary of the line conductor of the connector, and possibly to the calling operator.



   The single digit 1, numbered in the equipment, causes it to be tested for fuse faults. In response to the numbering of digit 1, line relays 610 and 630 transmit a single earth pulse, through earth to contact 681, contacts 634, 606 and 666, conductor 693, contact 715, conductor 694, contact 627, conductor 695, contact 784, conductor 739, contacts 108, 1024 and 1067, conductor 1098;

  <Desc / Clms Page number 106>

 contact 2413, one branch extending through relay 2420 to the battery, the other branch extending through contacts 2429, 2430 and 2431 and the coil of relay 2435 to the battery.

   Relays 2435 and 2420 operate, the latter relay closes to circuit 2424 a circuit for the delayed release relay 2425. At contact 2447, relay 2435 closes a holding circuit for itself, via relay 2428. and contacts 2438 and 2433. Relay 2428 does not operate until the earth pulse is removed from conductor 1098. When earth is disconnected from pulse conductor 1098, rela, is 2428 is energized. series with relay 2435; it transfers to contact 2434 the pulse conductor to the next counter relay. At contact 2441; relay 2428 operates the previously mentioned acoustic signaling circuit.

   Relay 2420 drops out shortly after the. termination of the pulse, to close contact 2421, whereby the acoustic signals are transmitted on conductor 1096, according to the state of the fuses. If there are no fuse faults, relays 2470 and 2474 are in the off position, and the dial signal and busy signal are applied through contacts 2471, 2446 and 2475;

   2445, and contacts 2448, 2421, to conductor 1096, intermittently, at about 4 second intervals. In the event that relay 2470 is actuated by the junction fuse fault conductor, one by the conductor - common equipment fuse fault source, contact 2475 is open, and the busy signal is sent to the attendant.



   To test for a voltage that is too low, a charging fault or a fault in the power supply network, the attendant dials a second digit 1. The earth at the impulse conductor 1098 activates relay 2450, by means of contacts 2412, 2429, 2430, 2434 and 2449.

  <Desc / Clms Page number 107>

 



  At contact 2451, relay 2450 maintains in series with transfer relay 2427, which is energized when the ground pulse is removed. Relays 2427 prepare at 2433 the pulse circuit for the next counter relay; it opens on contact 2438 the circuit of relays 2428 and 2435, which drop out. If the voltage is too low, the fault relay is at rest, and the dial current is intermittently connected to line conductor 1096, through contacts 2486, 2455, 2452 and 2422, for notify the operator. An absence of a dial signal indicates that the voltage fault relay 2485 has been actuated, via the voltage fault lead L V A.

   In the event that the 2490 chaxge relay and the 2494 network voltage fault relay are at rest, the busy signal is transmitted intermittently to the attendant, via contacts 2491, 2495 and 2454. A absence of a busy signal indicates that the load fault relay 2490 has been activated, either by means of. fault lead of the charging fuse or through the fault lead of the charging equipment. In the event of a fault in the public current distribution network, relay 2494 is energized via the network fault conductor, and the call signal is returned intermittently to the operator, at contact 2495.



   To transfer the call generators, the attendant dials a new number 1, to activate relays 2456 and 2426, in a similar manner. A short pulse is transmitted through earth, contacts 2423, 2425 'and 2458 and conductor 2405 to the generator transfer cells, which transfer from one call switch to another, in the well known manner.



  In the event that the call switch starts up quickly, an acoustic signal is transmitted intermittently to the operator by conductor 2408, contacts 2407 and 2459 and conductor 1096. In the event that relay 2480 is actuated by the driver

  <Desc / Clms Page number 108>

 generator fault, the call signal is transmitted intermittently to the operator, by contacts 2481 and 2406.



   To allow the operator to check if an equalizing charge is given to the battery, another digit is numbered, to energize relays 2460 and 2428, and release relays 2456 and 2426. If the battery is on. load relay 2410 'is kept attracted or otherwise the relay is at rest. The dialing signal is transmitted by contacts 2415 'and 2462 if the battery is not charging; if it is on charge, the busy signal is transmitted by contacts 2414 'and 2462.



   Dialing another digit 1 will stop charging, in case the battery is discharged, or put it on charge in case it is not. In response to this number 1, relays 2464 and 2427 pull in, and relays 2430 and 2428 drop out.



  When relay 2420 drops out, and during the. tripping time of relay 2425 After the pulse, a short earth pulse is extended through contacts 2411, 2423, 2425 'and 2467, to the upper and lower windings of relay 2410', and to the winding top of relay 2420 ', by contacts 2422' and 2413 '. The relays 2410 'and 2420' are both differential, from which it follows that the relay 2420 'is only actuated by the above circuit.

   At contact 2422 ', relay 2420' connects earth to the upper windings of relays 2410 'and 2420', to hold relay 2420 '. When the brief pulse to relays 2410 'and 2420' is terminated, by de-energizing relay 2425, the circuit crossing the lower winding of relay 2410 'is open, from which it follows that relay 2410' is then energized, since only its upper winding is excited.



  At contact 2416 ', relay 2410 closes a circuit for charging in the well-known way. At contact 2414', the signal 'occu-'

  <Desc / Clms Page number 109>

 pation is substituted for the dialing signal, and is transmitted to the operator by contact 2466, to inform her that the charge has started * In the event that the charge is in progress, when the attendant activates relay 2464, relays 2410 'and 2420' 'are actuated, and drop off by the brief pulse transmitted' during the tripping time of relay 2425. This brief pulse is extended by contact 2412 'to the lower winding. laughing at relay 2420 ', causing it to drop.

   When the earth pulse is removed, the upper winding circuit of relay 2410 'is opened, and this relay drops out, to stop the load, opening the load circuit at contact 2416'. To disconnect, the attendant withdraws from the connection, to release the repeaters, the searcher and the connector, as described previously. In response to the release of the connector, earth is removed from conductor 1097 to drop relays 2410 and 2402. Relay 247¯ drops out when contact 2414 opens, the last counter relay actuated and the last transfer relay actuated, such as relays 2426, 2427 or 2428, also drop out when contact 2413 opens. Intermittent operation of relay 2442 is stopped at contact 2415.



   A key A K is provided in the testing equipment, to allow the auditor to determine which faults are present.



  In response to. operation of the check, the battery via resistor 2416 and contact 2417 of the key turns on the lamps, such as the fuse fault lamp F L., the generator fault lamp GL, the fault lamp of the voltage VL, and the load lamp CL, according to quite obvious circuits, in the event that the corresponding fault or load relays are attracted.


    

Claims (1)

CLAIMS. 1.- Telephone network using relay switches, each having group and unit relays, in which a switch is designed so that it can be connected to one of the junctions of a group, under the control of common equipment, which causes the actuation of the appropriate group and unit relay in accordance with. first available junction of the group, and simultaneously prevents the establishment of a connection between a second switch and a junction of the same group. 2.- Telephone network using relay switches, each having group and unit relays, in which a switch is designed so that it can be connected to one of the junctions of a selected group, under the control of a common equipment, which comprises the means necessary to preselect the first free junction in each of the groups accessible to the switch, and the means which intervene, in response to the initiation of a connection with said group of junctions chooses, to cause the operation of the appropriate group and unit relays, so as to obtain the connection of the switch with the pre-selected free trunk of the required group. 3.- Telephone network provided with relay switches, having group and unit relays to make connections with the desired lines, in which the same group relay but different unit relays are activated in each case in response to different digit dialing, to connect to a designated line, as determined by the numbered digit. 4.- Telephone network provided with relay switches, using group and unit relays, and having access to different groups. <Desc / Clms Page number 111> lines in which a group relay and a unit relay are actuated in response to the numbering of a digit, to make a connection with a free line of a group, and in which the same relay of group and a different unit relay are actuated in response to dialing a different digit to make a connection to a free line in a second group, while if all lines in the first group are busy, the second relay number of units is activated in response to the dialing of the first digit:,. in order to establish the connection with a free line of the second group. 5. - Telephone network using searcher-connector circuits having access to subscriber lines, and groups of junction lines, and having facilities making it possible to restrict the connections established on the circuits, in which each seeker circuit -connector is provided with a group of service relays, actuated either individually or in groups, by marks applied to the lines having access to the connection circuits, the operation of the relays serving to restrict the connections that the different classes lines are able to be established through the connection circuits, as well as to allow additional facilities when one of them is used by an operator. 6. - Pulse repeater device, intended for use in a telephone network, comprising a line relay, a pulse relay and a pulse repeater relay, the pulse relay being actuated upon release. of the repeater relay, at the start of a pulse, while the reactivation of the repeater relay, to end the pulse, depends on the reactivation of the line relay and the pulse relay, the operating time of the latter relay being set so that the de-energization period of the repeater relay is sufficient to ensure a repeat- <Desc / Clms Page number 112> satisfactory pulse tition. 7.- Pulse repeater device, intended for use in a telephone network, comprising a line relay, a pulse relay which follows the line relay and two pulse repeater relays, the first of which is controlled by the pulse relay, and the second is controlled by the first pulse repeater relay and the pulse relay, the arrangement being such that each repeated pulse begins when one of the contacts of the first relay is opened pulse repeater, the duration of each repeated pulse comprising only the actuation time of the second pulse repeater relay, and the tripping time of these two relays ,. regardless of the operation of the other relays. 8.- Telephone network with long distance connections extending from an automatic central office to an operator position of another central office, and provided with devices through which the operator is able to dial in. return to trunk junctions, in which the trunk junctions are preselected for use by a distributor, and each dial-back repeater is provided with a connection relay for each trunk and a chain. back-dialing relay comprising an individual relay for each back-dialing repeater, each backward dialing relay being common (at trunk junctions, the arrangement being such that a dial-back relay is actuated when a connection is extended to a pulse-back repeater, and controls the operation of the connection relay corresponding to the trunk, preselected trunk, through what the connection is extended to. operator position. 9. A telephone network according to claim 1, wherein <Desc / Clms Page number 113> means are provided to prevent a second switch from being simultaneously connected to a junction of the same group or of a different group. 10. A telephone network according to claims 1 and 2, in which one of the groups of junctions is larger, and is provided with individual equipment for associating a calling switch with a free junction, in order to allow the simultaneous establishment of connections with a trunk of the group and a trunk of another group. II.- Telephone network according to claims 1, 2, 9 and 10, in which the common equipment comprises a group of junction selector relays belonging individually to each junction group, to preselect the first free junction of, its group, a group of trunk access relays, each individual to a switch, and a group of trunk group relays for each trunk group, one trunk access relay and one trunk group relay being actuated in response to the initiation of a connection on a particular group of trunks by a particular switch to establish the connection. 12-. Telephone network according to claims 3 and 4, in which means are provided to avoid congestion, when all the lines of a group are busy, whereby, when the representative digit of this group is numbered, the relay d The units associated with another group are activated to establish the connection with a free line of the other group. 13. - Telephone system according to claims 3, 4 and 12, wherein each group of lines is provided with a group of junction selector relays, to preselect the free lines of the associated group, while the first group of lines is equal. - equipped with a group of junction congestion relays, <Desc / Clms Page number 114> requested by the second group of junction selector relays, in accordance with the state of the junctions of the second group, to enable. the connection to be made with a free line of the second group, if all the lines of the first group are busy. 14.- Telephone system according to claims 1 to 4 and 9 to 13, in which each switch is provided with a group of conductors, through which the group and unit relays can be actuated, the conductors being associated with the common equipment, during the operation of the group access relays, while the group and unit relays are controlled through them, due to the operation of the junction group selector relays and junctions. 15.- Telephone network according to. Claim 14, wherein the group and trunk group access relays are actuated in response to a particular digit transmitted to the switch. 16. A telephone system according to claim 15, wherein each group of junctions is provided with a group of marking conductors common to all the switches, marking potentials being applied to the conductors by the operation of a junction selector relay associated with a free junction line. 17.- Telephone network followed claim 16, in which arrangements are made such that only one of the relays is actuated at the same time, and that a switch to be connected to a line of the group is controlled by the potentials. marking conductors, to commission the preselected junction line. 18. - Telephone network according to claims 14 to 17, in which, when a trunk line is taken in service, the associated junction selector relay is released, and the junction selector relay associated with another line. free is activated. 19. Telephone network according to claims 14 to 18, wherein the preselection of the free junction lines is effected by cyclic actuation of the junction selector relays. <Desc / Clms Page number 115> 20. - The telephone network of claim 16, wherein the marking conductors include a busy conductor, to which a marking potential is communicated when all the junctions of the group are occupied. 21.- The telephone network followed claims 14 to 19, in which a recovery relay is associated with the junction selector relays, and is actuated at the end of each cycle of operations, the next cycle starting immediately if a free junction is available . 22. - The telephone network of claim 21, wherein the recovery relay controls a delayed trigger relay which is released when the recovery relay remains attracted longer than a determined period, indicating that all the junctions are occupied; said time delay relay serving to apply a marking potential to the full occupancy conductor. 23. - Telephone network according to claims 1 to 4 and 9 to 21, wherein the switches are provided with a timing device which occurs when the switch is associated with the common equipment, and wherein, if the switch does not The connection to the desired outlet is not established within a specified time, a busy signal is returned to the calling subscriber and the next trunk line is pre-selected. 24. - Telephone network according to claim 23, wherein the timing device is common to all the switches, and comprises a delayed tripping relay, the circuit of which is open when the common equipment is taken up, and is closed when 'a free junction is entered. 25. - Telephone network according to claims 1 to 4 and 9 to 21, wherein the connections are established by the intermediary of searcher-connector circuits which are controlled by a distributor. <Desc / Clms Page number 116> caller, to search for a calling line, and in which a timing device is provided to release the distributor if it does not find a calling line within a determined period, the timing device comprising a set of conductors by means of which pulses are transmitted at determined time intervals, to control means provided in the distributor to produce the release thereof if it has not found the calling line within a determined time. 26. A telephone network according to claim 25, wherein the timing device controls two relays, the first of which operates when the distributor is taken in use, and drops when the calling line is found, while a pulse - The signal is delivered by the timing device, a determined time after the dispenser has been taken into service, and actuates the second relay if the first is still actuated, thus causing the release of the dispenser. 27.- Telephone network according to claims 25 and 26, in which the distributor comprises relays of tens and units, actuated by marks of a subscriber line; the tens and unit relays drop to release the dispenser either when the calling line is found or under the control of the timing device. 28. The telephone network of claim 27, wherein the release of the units and tens relays is normally effected by releasing the line relay in response to the operation of the cutoff relay. 29.- Telephone system according to claims 1 to 4 and 9 to 28, in which each switch comprises several counting relays, which respond to a number transmitted to the switch, <Desc / Clms Page number 117> indicative of a particular group of junctions to which the switch has access, the counting relays controlling independent circuits for a group relay of the switch, for a junction access relay common to all the groups of junctions, and for a trunk group relay, through contacts of the trunk access relay, which is drawn, according to the digit which is transmitted to the switch. 30. - The telephone network of claim 29, wherein the operation of the switch group relay closes points of the circuits of all groups of junctions to which the switch has access, establishing the connection to a free junction. with a particular group being carried out under the control of the junction group relay and a junction selector relay. 31.- Telephone network according to claims 29 and 30, in which the establishment of the connection to the free junction causes the release of the counter relays and of the group access relays and of the group of junctions relays, which become then available for establishing other connections. 32. - Telephone network according to claim 29, wherein the counter relays respond to a final digit numbered by the calling subscriber for the selection of the appropriate ringing code, and a relay which is energized after the transmission of the last digit is arranged. so as to delay the release of the counter relays until the called subscriber has answered. 33. - Telephone network according to claims 1 to 4 and 9 to 32, in which connections are established by means of searcher-connector circuits, provided with a common distributor, and having means for recording the state of total occupancy, these means comprising a recovery relay common to the connection circuits, which can be actuated when all <Desc / Clms Page number 118> connection circuits are occupied, and a delayed release relay, controlled by the recovery relay, and capable of activating a total circuit occupancy recorder, if the recovery relay is kept pulled for a time greater than the tripping time of the delayed release relay. 34. The telephone network of claim 5, wherein the operation of the relays in different combinations, in response to entry of the connection circuit by a particular line, controls the operation of a trunk access relay, according to the number transmitted on the line, thereby determining the group or groups of trunk lines with which the particular line is able to make the connection. 35. A telephone network according to claims 5 and 34, wherein the operation of the relays in different combinations prevents the operation of a group access relay in response to seizure of the connection circuit by some. lines, to establish a connection with a particular one of the trunk groups, to allow the operation of the group access relay, if the connection is intended for another trunk group, and to allow the operation of the relay group access for connections from other lines, for one or other of the trunk groups. 36. - Telephone network according to claims 5, 34 and 35, wherein there are provided three service relays, four classes of service restrictions being obtained by actuating three of the relays in isolation and two of them simultaneously. 37. A telephone network according to claims 5, and 34 to 36 in which another service relay is actuated if the connection circuit is taken in use by an operator, to disconnect the timing mechanism provided in the connection circuit. connection. 38. The telephone network of claim 37, wherein the operation of the relay enables the operator also, in <Desc / Clms Page number 119> numbering a single digit, to have access to a busy line. 39. Telephone network according to claim 37, in which the operation of the relay also allows the operator, by dialing a single different digit, to activate a verification switch, which responds to the pulses of numbers to carry out pre-planned tests in the equipment. 40. - Telephone network according to claims 38 and 39, wherein the relay is actuated by a special service conductor, which forms part of a circuit which is temporarily closed by the common equipment during the establishment of the connection. - ion. 41. - The telephone network of claim 5, wherein, if a connection circuit is seized by a trunk line to establish a connection through an outgoing repeater, a potential is connected from the connection circuit. ion to a repeater conductor, so as to disable the repeater timing device. 42. A telephone network according to claim 38, wherein the busy signal is transmitted when a requested line is busy, if the calling party is a subscriber, while a battery reversal is occurring. transmitted if the caller is an operator. 43. - Pulse repeater device, according to claim 7, in which a holding relay is provided, and is controlled by the first pulse repeater relay and the pulse relay, the holding relay being maintained independent of the first pulse repeater relay, and serving to prepare the pulse relay for operation again, in response to the operation of the line relay. 44. - The telephone network of claim 8, in which each trunk junction is provided with a conductor of <Desc / Clms Page number 120> marking, one of which is marked when a trunk trunk is preselected for use, the operation of a dial-back relay serving to extend each marking conductor to the corresponding connection relay of the dial-back repeater, only the connection relay corresponding to the preselected trunk trunk being actuated to associate the dial-back repeater with the trunk trunk. 45. - Telephone network according to claims 8 and 44, wherein the operation of the connection relay serves to release the dial relay in return, to disconnect the marking conductors of the connection relays, whereby they are made available to participate in the establishment of a new call, while the distributor, in response to the connection of the dial-back repeater and the trunk trunk, functions to preselect another free trunk trunk. 46. - Corresponding telephone network substantially as described and shown in the accompanying drawings.