BE420417A - - Google Patents

Description

       

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  Improvements to telephone systems.



   The present invention relates in general to telephone systems and more particularly to means intended to control the collection and reimbursement of coins deposited in prepaid devices.



   The main object of the present invention is to provide a new device and a new circuit by means of which an operator can control the collection or reimbursement of coins deposited in local or remote offices.



   Another object of the invention is to provide a new circuit, operated in both directions, connecting the local office and the remote office and controlled by the operator. for

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 collect or reimburse coins due for incoming and outgoing calls made on these junctions.



   Another object of the invention is to provide an improved line circuit intended for prepaid stations, in which, if the operator forgets to collect or refund the deposited change, she is immediately notified of this when the connection is released.



   One of the characteristics of the invention relates to a new repeater for an individual prepaid set with certain connectors used by the operator to establish communications to the lines of the prepaid sets.



   Another characteristic of the invention relates to the means employed in the circuit operated in both directions and by which the operator can call back through the junction the line of the calling prepaid set.



   Another characteristic relates to the control means, made available to the operator, to set up delayed calls to prepaid sets and by which a common transmitter is primarily used for controlling the automatic switches which set up the connection to the calling line and then for the control of other switches which complete the connection to the called line.



   Another feature relates to the means available in the trunk circuit operated in both directions to allow the operator of the remote office to momentarily reconnect the special tone of the prepaid stations to the wires of the trunk circuit for the purpose of to check that it is indeed a prepaid set calling.



   Another characteristic relates to the means placed under the control of the operator and by which only certain categories of calls, such as those coming from the sets.

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 prepaid, can be used by an attendant position.



   Other characteristics of the invention which are not especially indicated here will become evident in the course of the description which follows.



   Referring now to the plans comprising figs, 1 to 19, inclusive, it can be seen that fig. 1 shows a line circuit A of an automatic prepayment station and a rotary preselector C; fig. 2 shows one of the repeaters for prepaid stations accessible from the rotary preselectors; fig. 3 shows schematically, in the upper left part, the primary selector SELI individual to the repeater of the prepaid station, in the remainder of the fig, is shown a portion of the trunk circuit TC connected to the remote office; fig. 4 shows the remainder of the TC junction circuit and the two wires which terminate at the remote office; fig. 5 schematically shows an arrival selector SEL2, accessible from the TC junction circuit shown in FIGS.



  3 and 4, this selector has access to connectors, one of which is shown in the remainder of FIG. 5. The connector of fig. 5 has access to normal subscriber lines and also to prepaid lines, one of which is shown in FIG. 1; fig. 6 in its upper part shows the TC junction circuit at the remote office which is accessible from the circuits of the researchers, one of which is shown in figs 7 and 8, and of the selectors, one of which is shown in fig. 12.

   The lower part of fig .6 shows an LED junction circuit for deferred calls accessible from the first level of searchers and an associated selector SEL3 and has access to the junction circuit to the remote office and to the control circuits of the researchers. prepayment stations one of them being shown in fig 13;

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 figs 7 and 8 are researcher circuits. The researchers' connection circuits have access to the junction circuits such as those shown in fig. 6, to the line circuits of manual prepayment stations A1 and to other circuits which are not shown; fig. 9 in its left part shows how the STL starting wires of the various circuits are connected to the vertical banks VB of the researcher circuits.

   In the lower left part is represented the distributor which designates the one of the operator positions (Pos 1, Pos 2, Pos 3, Pos4) which must answer the call. The rest of fig. 9 shows the handset, chest microphone and headset telephone, OH of the operator and part of the position relays? 1. fig, 10 shows the relays of the operator position intended to connect the latter to the circuits of the researchers; fig. 11 shows the group of keys of the operator's position which are used to control the various functions; fig. 12 shows the selector connected individually to the finder circuit of figs. 7 and 8, this selector has access to the control circuits of the prepaid stations, one of them being shown in FIG. 3, and to the TC junction circuits, one of them being shown in FIG. 6;

   FIG. 13 shows one of the circuits of the prepayment stations accessible from the selector. The control circuit of the prepaid station is individual to the connector CON shown schematically in the right part of fig, 13. This connector has access to the lines A1 of the manual prepaid stations, one of them being shown in the figure. fig. 14; FIG. 14 shows the line of a manual prepayment station and the line circuit A1 of the manual prepayment station, which ends in the bank of researcher circuits;

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 Fig. 15 shows schematically the circuits for checking the money in an automatic office, Figs, 16 and 17 schematically show the circuits for checking the money at the remote office; fig. 18 is a outline showing how the different figures are to be assembled;

   FIG. 19 is a layout plan of the various figures schematically showing the control of the currency.



   The apparatus A collecting the currency and shown in FIG. 1 may be of the well known type such as that shown and described in Patent No. 1043219 filed in the United States of America. The preselector of FIG, 1 can be of the well-known rotary type in which the brushes have no normal position, always remaining engaged on the bank contacts associated with the junction circuit used last. At T 'is shown a tone-generating machine, the function of which is to give a discriminating tone to the recording operator who would be called through this station with the aim of making the quality known. of the one who calls him, that is to say to allow him to obtain or not certain connections.

   The repeater circuit of the prepayment station shown in fig. 2 is similar to the repeaters of prepaid stations represented in Patent No. 1644968 filed in the United States of America, and in Patent No. 1909025 filed in the United States of America. The SEL selectors shown in fig. 3, 5, 6 and 12 are of the two-motion Strowger type, in which the selector test brush looks for negative polarity to make the desired connection. These selectors are similar to the LS selector shown in Fig. 1 of Patent No. 1971,505.



   The connectors shown in fig. 5 and 13 are of the two-movement Strowger type, they are similar to the con-

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 nectors shown in fig. 3 of Patent filed in the United States of America N 1971505. The circuit of the researcher of FIGS. 7 and 8 includes the Strowger type finder scope with two movements which works step by step along the vertical to the desired level under the control of the vertical test broom to find the desired group and which then operates step by step in rotation to find the calling line in the selected level.



  As shown in the present application, the researcher is represented as having access only to the first, eighth and ninth levels, it being understood that the remaining levels of the researcher are used for other kinds of service which are not the object of the present invention. In the lower corner of fig. 8 is schematically shown a transceiver circuit SL and a transceiver RS. This transmission and recording circuit is identical to the circuits of the same nature described in Belgian Patent N 325258 filed on September 16, 1936. Each operator position is provided with a group of number keys by means of from which it can record the transmitted digits in the transceiver.

   Transmit circuits are used to connect the transceiver to the searcher circuit in service at this operator position. Figs. 9, 10 and 11 show one of the operator positions. Each operator position has a number of finder circuits through which the operator can establish the desired connection. Figs. 7 and 8 show only one of the circuits of the individual researchers at the operator position shown in FIGS. 9, 10 and 11.



  The DIS distributor shown in fig. 9 is used to select one of the four attendant positions. In the upper left corner of fig 9 are shown the STL starter wires which come from the line circuit of the manual prepaid station of fig, 14 and the junction circuit of fig. 6

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 and the other starting circuits for the other categories of lines which end in the researcher's benches. The operator has a TS key for switching the junction to control the circuit of relay 810 so that, if desired, the searcher shown in fig. 7 and 8 can only be used for certain categories of calls.



   The manual coin-operated apparatus shown in FIG. 14 is similar in construction to the mechanism of the well-known coin-operated station to which reference has already been made in FIG. 1.



   In order to explain the operation of the various circuits, it will first be assumed that someone wishes to make a call from prepaid station A to a subscriber of the remote manual office and that the person in question is trying to obtain the call. without first depositing a coin in the coin-collecting mechanism of the coin-operated station.



   When the receiver of station A is lifted, the line relay 26 of the individual preselector C attracts via the two components of the calling line in series. The relay 26, by attracting, at its contact 40 establishes a circuit which comprises the switching relay 25 and the control electromagnet 27 in series and at its contact 39 it connects the test brush 46 to the circuit. described above at an intermediate point between the switching or breaking relay 25 and the control electromagnet.

   The operation of the preselector C depends on whether the junction line, of which the brushes 44, 46 and 47 are engaged, is occupied or not, If it is assumed that the line is occupied, there will be a ground connected to the test contacts on which is engaged the test brush 46, the switching relay 25 will be bypassed and the control solenoid 27 will receive a direct positive through the test brush to operate the selector as a switch.

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 buzzer, that is to say to advance the brooms step by step in search of a free junction line. However, it will be assumed, in the present case, that when the receiver is off-hook at station A, the brushes 44, 46 and 47 included, are engaged on bank contacts associated with a free junction line.

   Under these conditions, immediately after the attraction of the relay 26, the relay 25 attracts since it is not short-circuited. By attracting, the relay 25 disconnects the line wires 11 and 12 of the coin-operated station from the winding of the relay 26 / from the earth and extends them through contacts 35 and 36, brushes 44 and 47 , contacts 52 and 55, wires 48 and 51, springs 145 and 144 and their rest contacts, upper and lower windings of differential relay 150 and thence through the windings of line relay 135 and the windings of impedance coil 139 to negative and positive respectively.



   Line relay 135 of the repeater shown in fig. 2 attracts in the circuit of the two wires of the calling line connected in series, at its contact 183 it closes the circuit of the release delayed relay 136 by means of the positive given to the contact 162. The relay 136 therefore attracts and at the release. contact 182 places a positive on the junction circuit release wire 50 via the choke coil 138, which establishes a blocking circuit of the preselector C which borrows the bank contacts 54, the brush 46, the contact 35 and its contact at work, the winding of the relay 25, the winding of the control electromagnet 27 and the negative.



  It is seen that the blocking circuit closes before the release delayed relay 26 has had time to release after its circuit has been cut by the relay 25. A branch of the blocking circuit also extends through the intermediary.

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 from the normal private wire 498 to the multiplied test contacts of the connector banks which have access to the line from station A, thereby the line is protected against any intrusion in the well known manner. It will be remembered that the positive is supplied by the release wire of the junction circuit 50 through the coil of choke 138. This coil has a very low resistance, about 2 1/2 ohms, so that the contacts are multiplied. of the test contact accessible from the other preselectors are marked occupied.



   When relay 136 attracts it completes, at its contact 188, the circuit of the polarization winding of relay 132, electrically polarized, in series with the winding of relay 141. The electrically polarized relay 132 is set so that the current flowing through its bias winding does not attract the armature of this relay, but if it has attracted, the current flowing in the bias winding is sufficient to maintain the armature attracted. Relay 141 is therefore the only relay that attracts in this circuit. When the relay 141 attracts it opens at a point a certain branch circuit which will be described later.



   When the relay 135 attracts, in the repeater, a bridging circuit closes via the line wires 200 and 202, it borrows: the wire 200, the normally closed contacts controlled by the spring 172, the spring 190 and its contact at rest, the contacts normally closed and controlled by the spring 160, the upper windings of the relays 133 and 128, the on contact and the spring 184, the contacts normally closed and controlled by the spring 164, the contacts closed normally and controlled by spring 173, the top winding of relay 132, wire 202. When this circuit closes the selector line relay

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 tor shown schematically in FIG. 3 and marked SEL1, attracts.

   When it attracts this line relay closes the circuit of the release delayed relay R which attracts to prepare the selector operating circuit in the usual way and to place a positive on the release wire 201 of the junction circuit. The direct positive connected to wire 201 short-circuits relay 141 of the repeater and this relay releases, at its spring 196 and its contact at rest it closes the branch circuit placed on the pulse spring 184 of the line relay 135 of the repeater. It can now be seen that with the branch circuit established on the impulse spring 184 any subsequent attraction of the line relay 135 will have no influence on the selector and that the call will not be prolonged.

   So that the branch circuit cannot be established on the impulse spring 184, it is necessary for the appellant to deposit a coin in the coin-operated mechanism of station A.



   The person who uses the station A therefore deposits a coin of a determined value in the mechanism provided for this purpose. This mechanism is well known and its operation does not require any detailed explanation. When the coin is introduced into the post it descends and passes through the trigger mechanism which it actuates, it follows that the polarized electromagnet PM of the cashing mechanism is connected to the line wire 12. The part is retained by a movable valve from where it can be cashed or refused under the control of the polarized electromagnet PM. The part can be deposited either before or after the receiver has been untied.

   In either case, the last operation brings about the operation of the rotary preselector C, therefore the line is extended to a free selector as has been described.

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   If we assume that the selector of fig. 3 is the selector in question the operation is the same as that described with one exception, however, when the line wires 11 and 12 are connected as a result of the operation of the preselector C to the windings of the line relay 135 and from the choke coil 139 the positive of the line wire 12, through the polarized electromagnet of the collection mechanism unbalances the differential relay 130 which is incorporated in the line circuit and causes the attraction of this relay. It should be noted at this point that the polarized electromagnet PM of the station is of strong resistance and that it does not in any way prevent the transmission of impulses or conversation, but it is nevertheless sufficient to cause the attraction of relay 130 as described.



   When it attracts its armature, the relay 130 closes the circuit of the relay 134 via the contact at rest and the spring 191, the contact 186 and the positive. When it draws relay 134, establishes its own blocking circuit at spring 178, it thus blocks at the release wire of junction circuit 201. Relay 134 at contact 181 prepares a circuit which will be described later, at its contact 180 opens the branch circuit on the pulse contact 184 which allows the certain establishment of a call whether the relay 141 is attracted or not.



   The person who telephones from set A can now activate the calling device to send the digits necessary for the operation of the selector which must enter a TC trunk / circuits connected to the remote office. In this case, if we assume that the number 0 has been emitted by the one using station A, the line relay 135 will release ten times, at contact 184 it interrupts the circuit to the selector line relay ten times for cause the brushes to advance

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 selector up to the tenth level after which the selector automatically rotates in the well-known manner to select a free junction circuit.

   When the repeater relay 135 releases under the action of the first pulse, the relay delayed on release 137 draws into the following circuit: positive taken at contact 162 and its contact at rest; contact 183 and its contact at rest, contact 187, winding of relay 137, negative. This relay therefore attracts and, at the contact 191 and its working contact, establishes the circuit of the relay 129 by means of the positive and the contact 186, and of the normally closed contacts controlled by the contact 167 of this relay. Another result of the attraction of relay 137 is that at contact 190 and its working contact a direct bridge is placed on the junction wires 200 and 202 which do not include the upper windings of relays 133 and 128.

   These circuit modifications are made to reduce the resistance and impedance of the selector control circuit to a minimum during pulse transmission. When it draws the relay 129 to its contact 167, it blocks itself at the junction release wire 50, while at its contacts 165 and 168 it short-circuits the upper and lower windings of the differential relay. 130 incorporated in the pulse circuit of line relay 135.



   The delayed release relay 137 releases after the transmission of the pulses to reincorporate the upper windings of the relays 133 and 128 in the circuit which goes to the selector.



   Since it has been assumed that the TC junction circuit shown in figs. 3 and 4 is the junction circuit entered by the selector, at the moment of plugging the following circuit is established: positive, through the winding of the control relay

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 mutation of the selector via the selector test brush 205, bank contact 208, contact 254 and contact at rest, winding of relay 280, negative. When it draws the relay 280 to the contact 279 in this circuit, the wire 249 is grounded to cause the relay 390 to be attracted, at the contact 278 it locks to the release wire 247 of the grounded junction circuit. At contact 276, relay 280 disconnects the negative of wire 247, thereby removing one of the negative polarities which marked the junction circuit as free.



  At contact 289, relay 280 prepares at one point the circuit of call relay 300, at contact 288 it prepares at one point the circuit of relay 290 for checking the currency, at contact 287 it prepares the circuit of relays at one point 320 and 330 tone switches, at contact 286 it prepares the circuit for reversing relay 240 at one point, at contacts 285 and 284 it connects line relay 310 to the line terminals instead of relays 220 and 230 At contact 283, relay 280 connects the call tone return circuit, at contacts 281 and 282 it disconnects the conversation wires from the incoming selector junction circuit to the idle contacts of these contacts. and when the contacts are on, it closes the supply circuit of relay 310.

   When the auxiliary transfer relay 390 attracts, at contact 391 it places the alternating current relay 380 to the bones of the conversation wires, at contact 392 it opens the circuit which ends in the release wire 215 of the junction circuit of the incoming selector, on contact 393, it earths the starting wire 256 of the calling machine to start it.



   The power supply circuit of relay 310 is as follows: positive and negative through the lower and upper windings of relay 310 respectively, wires 227 and 225, springs 285 and 284 and their working contacts, wires 226 and 224,

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 left windings of the RC translator coil, wires 219 and, 218, contact at rest and springs 294 and 292, springs 281 and 282 and their contacts at work, contacts at rest and springs 242 and 241, contacts at rest and springs 212 and 211, bank contact 207 and 206, brushes 204 and 203, wires 202 and 200, upper winding of polarized relay 132, normally closed contacts controlled by springs 173 and 172, spring 190 and contact at rest, normally closed contacts controlled by the springs 164 and 160, impulse spring 184 of the line relay 155,

   upper windings of relays 128 and 133. At contact 311, relay 310 completes the power supply circuit of release relay 350. When it draws relay 350 to contacts 351 and 352, reverses the negative and positive connections on the junction wires 308 and 309, at contact 353 it puts wire 234 to earth to attract relay 250, at contact 354 it prepares its own blocking circuit, at contact 355 it connects the positive through contact 332 or the lower winding of the impedance coil 335 to the release wire of the junction circuit 247 to keep the latter connected to earth.

   When it draws the relay 250 to the contact 252 completes the circuit of the lower polarization winding of the relay 230 and the supply circuit of the inrush relay 200 via the contacts 263 and 289 and the wire 236. At contact 253, relay 250 at one point prepares the blocking circuit of relay 220, at contact 254 it connects grounded wire 246 to release wire 247 of the junction circuit.



   When it pulls the relay 300, to the springs 301 and 302 at their working contacts, connect the positive and the generator to the jumper wires 308 and 309 to pull the AC relay shown in fig. 6. At contact 303, relay 300 connects the generator through the resistor,

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 the capacitor and wire 255 to the lower winding of AC relay 260 to cause its attraction.



  At contact 261, relay 260 disconnects the negative of the winding of relay 370, at contact 262 it opens the circuit of relay 270 at one point. With its contact at rest, at its contact at work it prepares the circuit of relays 320 and 330 tone switches, at contact 263 it opens the circuit of the call relay 300 and at contact 264 it closes its own blocking circuit by means of the contact 252 which is grounded. After a certain time, the inrush relay 300 releases and disconnects the earth and the generator GEN from the jumper wires 308 and 309, it opens the primitive supply circuit of the alternating current relay 260 now blocked in position of. job.



   The momentary attraction of the inrush relay 300 causes the temporary sending of the current, supplied by the generator, on the junction wires 308 and 309 to cause the current relay, alternating to be drawn into the following circuit: and generator to the automatic office, jumper wires 308 and 309 terminating at the remote office, normally closed contacts controlled by springs 521 and 512, spring 551 and closed contact, contact 531, capacitor C, upper winding of relay 530. AC relay 530 attracts in the circuit described above, at contact 532 it closes its own blocking circuit through its lower winding in series with start relay 540. Relay 540 attracts in series with the lower winding of relay 530, at contact 541 it prepares the conversation circuit at a point.



  At contact 542 the relay 540 earths the wire 583 which goes to the selector banks to mark this junction circuit to the occupation for all the selectors which have access to it, to the contact 543 it connects a negative, through the winding of relay 550, at bank contact 574 in the level

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 wanted from the researchers' benches, the eighth for example, to mark this junction circuit as calling, at contact 544 he prepares a new circuit for relay 540, at contact 545 he puts wire 590 to the ground to attract relay 819 of fig. 9 and to mark the contact of the eighth level of the researcher's vertical bench and thereby mark the group in which this junction circuit is located.



   Start of researchers.



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Referring to fig. 9 which shows the common STL starting wires and the common distributor DIS it can be seen that there are nine starting wires, bearing the numbers 2 to 0. These numbers indicate the levels of the researchers at which the starting wires are respectively associated. It can be seen that wires 2-9 go to correspondingly numbered contacts in the seeker's vertical test stand VB on which the vertical test brush 607 engages when the main brushes are located. opposite levels 2 to 9 respectively. These wires are intended to stop the seeker's brooms in front of the first calling level as they rise to answer a call.

   It can also be seen that the tenth contact of the broom bank 607 is permanently grounded so as to stop the broom anyway when it reaches the tenth or last level. Note also that the STL starter wires marked 2 to 7, inclusive, run, through normally closed contacts controlled by relay 810, to the vertical bench. This arrangement has been provided so that if desired one of the operator positions can be reserved for answering and setting up calls of a certain category such as those from prepaid sets, those intended for long distance offices etc.

   In the case where

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 the operator in position 1 wishes to answer only long distance calls and those from prepaid key sets. TS will be actuated to release relay 810, which disconnects the starter wires 2 to 7 included, from the researchers' VR vertical benches. Starter wires 2 through 7, inclusive, are connected to the vertical bench, individual seekers at this position can only be connected to calling lines ending in the eighth, ninth or tenth levels which have been reserved for special call categories.

   In this case, as the common start relay 819 is attracted by the intermediary of the grounded starter wire 590 this relay at contact 818 establishes the circuit of call lamps Ll at all operator positions, on contact. 846 it connects an earth to the lower contacts of the distributor selection relays by means of the springs 847 and 848. In the event that the call was made by another line, which would have the function of putting a Any of the starter wires 2 through 7 included to ground, the common starter relay 820 pulls in and on contact 817 burns the L2 lamps at all operator positions. , To contact 817, it also connects the lower contacts of the distributor selection relays.

   The pre-selection of the operator position by the distributors of FIG. 9 will be explained below.



   Each attendant has been instructed to activate the call key of a trunk circuit that is free and ready to receive a call when it is not busy answering another call. The attendant is able to find at any time the junction circuits which are in service and those which are not by observing the supervision lamps and the occupancy lamps shown in fig. 8.



   /

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Preselection of a junction circuit.



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If we now assume that the operator in the position marked? 1 is not occupied and wishes to pre-select a seeker or answer a call, and if it is further assumed that the fact that the occupancy lamp BL in fig. 8, not being on, indicates that this search engine and the selector associated with it are not in service, the operator then activates her conversation key K2 in FIG. 8. As a result of putting the key K2 in the talk position, a circuit is closed via the common test lead 753 and the upper winding of the connection relay 650. The test lead 755 is one of the cables. common wires contained in the cable shown and this wire is multiple to the other individual junction circuits at the position, it is normally earthed at contact 853 of fig. 9.



  The excitation circuit of relay 650 is as follows: spring 855 grounded and its contact at rest, test lead 753 included in the right cable, springs 744 of the key, lead 688, upper winding of the connection relay 650 , negative.



   When the relay 650 attracts, on contact 657 it establishes its own blocking circuit which borrows: positive taken through the winding of the relay delayed to attraction 850, the blocking wire 754 included in the right cable, the springs 745 key, wire 689, contact 657, lower winding of connection relay 650, negative. The relay 650 with its various contacts establishes the link between the connection circuit and the operator's equipment, this association being partially established by the actuation of the conversation key K2.



   Relay 850 draws in series with the winding of connection relay 650, when this relay draws it disconnects the earth from test lead 753 which prevents operation.

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 ment, from another connection relay in another connection circuit. Relay 850 also connects the lead wires from the RC translator coil windings (used for monitoring purposes) and extends them to the OH operator equipment. Relay 850 also extends the positive through contact 854, wire 892, and contacts 922 and 932 to the coil of relay 940 and negative, attracting this relay.

   The start relay 940, when it draws, at contact 941 prepares at one point the circuit of the signaling relays 860, 870 and 880, at contact 942 it earths the start wire of the distributor DS. To put the relays distributor selection in function, at contact 943 it puts the marking wire M to earth to mark this position as being available to receive a call, at contact 944 it connects the PS wire to the starter wire 638 to prepare the Seeker start relay 640 circuit.



   If it is assumed that the DIS distributor is in its normal position, which is the one shown, the connection of a ground to the DS wire causes the consecutive operation of relays 826,825, 824 and -823 which perform the test of a free position in which a connection circuit has been preselected in the manner just indicated. The pre-selected position, in this case position 1, is characterized by a positive connected to the M wire. The attraction circuit of the first of the distributor's selection relays comprises: the DS wire grounded through the springs 833, 834 and 835 and their contacts at rest, the winding of the selector relay 826 and the negative.

   When relay 826 attracts when closing its circuit to contact 845 it connects the CSC wire to the PS wire, to contact 844 it connects the M wire to the stop relay 822, to the contact

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 839 it closes the circuit of the second selection relay 825 by means of the earthed contact of the stop relay 822. In practice the relays 823 to 826 inclusive have a fairly hard setting while the relay 822 has a fairly hard setting. As a result, relay 822 will attract through the grounded M wire before the selection relay immediately following it, such as relay 825, can attract its armature. In the current case, the stop relay 822 attracts before the relay 825 and at contact 843 it opens the supply circuit of the relay 825 to prevent its operation.



   Taken from the calling junction circuit.



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If we assume that the connection circuit of Figs. 7 and 8 has been preselected as described above and further if it is assumed that the junction circuit of FIG. 6 has ground the start wire 590 as previously described relay 819 will pull to turn on lamp L1 at all positions and to ground the common CSC start wire through contact 846.

   The power supply circuit of the start relay 640 of the connection circuit is established as follows: contact 846 earthed, CSC wire, springs 847 and 848 and their contacts at rest, contact 845, PS wire, contact 944, starter wire 638 included in left cable, contact 658, vertical engagement springs 671 normally closed, starter relay top winding 640, negative. Relay 640, at contact 641, establishes a blocking circuit through its upper winding via cam springs 670 independent of vertical engagement springs 671.

   At contact 642, relay 640 prepares its blocking circuit through its lower winding, spring 643 and its contact.

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 at rest it opens at one point the circuit of the release electromagnet and on contact with this spring it energizes the lower polarized winding of the switching relay 610 and also establishes the circuit of the electromagnet of VM2 ascent, at contact 661 it puts wire 692 to earth to switch on the occupancy lamp BL, which shows the operator in this position that the connection circuit is busy.



  The polarized switching relay 610 does not pull when its lower bias winding alone is energized, it only operates when current is flowing through its upper energizing winding in the desired direction. The circuit supplying the VM2 ascent electromagnet is as follows: positive to the spring 643 and its contact on, contact 617, normally closed contacts controlled by the spring 631, spring 623 and its contact at rest, winding of the ascension electromagnet, negative. Each time the ascent electromagnet operates, the searchers' brushes rise one step vertically and on contact 672 the feed circuit of the advancement relay 630 closes.

   When relay 630 attracts, at contact 631 it opens the circuit of the ascent electromagnet and prepares the circuit of the lower winding of the reversing relay 620. The electromagnet causes the ascent to release. therefore and at contact 672 / the release of the advancement relay 630, the latter by releasing restores the supply circuit of the ascent electromagnet. Ascend solenoid and advance relay 630 interact as just described until vertical test broom 607 encounters a grounded vertical bank contact. where one of the grounded starter leads ends.



   In this case as the starter wire 590 is the starter wire which has been grounded, the brushes of the

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 seeker ascend vertically until the vertical test brush 607 meets the bank contact on which the starter lead 590 ends. At this moment the supply circuit of the transmission relay 620 in series with the The ascent electromagnet closes as follows: grounded starter 590 and the associated vertical bench contact, vertical test brush 607, contact 622, reverse relay lower winding 620, spring 631 and its contact at work, spring 623 and its contact at rest, winding of the ascent electromagnet VM2, negative.

   Relay 620 first closes contact 621 to establish its blocking circuit through its upper winding and through contact 643, grounded, then it closes contact 622 to open the supply circuit. primitive.



  The relay 620, on contact 623 opens the circuit of the ascent electromagnet VM2, on contact with the work of the spring 623 it prepares the circuit of the rotation electromagnet RM2. At contacts 624 and 625, relay 620 opens the circuits going towards brushes 605 and 606. When the circuit of the ascent electromagnet is open, this one releases, at contact 672 it releases. releases relay 630. When relay 630 releases the circuit of the rotation electromagnet RM2 closes as follows: spring 643 earthed and its contact on, contact 617, contacts normally closed and controlled by the spring 651, spring623 and its contact at work, winding of the rotation electromagnet RM2, negative.

   Far following the operation of the rotation electromagnet, the brushes 601 to 606 inclusive rotate and engage on the first group of bank contacts of this level and the vertical brush 607 is released from the vertical bench. On contact 673 the rotation electromagnet attracts the advance relay 630, thereby the latter to the normally closed contacts.

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 When controlled by the spring 631, the circuit of the rotation solenoid opens. Rotation electromagnet and advancement relay 630 interact in this circuit causing the finder brushes to advance step by step until test brush 604 encounters a bank contact connected to negative which is the polarity of a calling line.

   When the test brush 604 meets the bank contact to which the inrush polarity is connected, the supply circuit of the switching relay 610 and of the relay 550 in series closes as follows: positive, spring 643 and its contact working, top winding of relay 610, test brush 604, wire 574, contact 543, winding of relay delayed on release 550, negative.

   When relay 610 attracts, to contacts 611 and 612 it connects the conversation wires of the junction circuit of fig. 6 to the head and neck response wires of the operator circuit via contacts 651 and 653, at contact 615 it connects the positive to the lower hoarseness of the start relay 640 to keep this relay attracted , at contact 616 it short-circuits the upper winding of relay 610 thereby connecting a direct positive to the contact of the bank to which this junction circuit ends to make it occupied for the other researchers who have access to it, to the bank contact. contact 617 opens the blocking circuit of the reversing relay 620 which releases. The relay 610 is maintained in the working position under the action of its polarized lower winding alone.



  At the finder's first step of ascent the shaft springs 671 open their contacts but the starter relay remains attracted at this time by the intermediary of the cam springs 670 and the starter wire 638. The shaft springs 674 are engaged. close at the first step of ascent of the seeker brushes to prepare the circuit of the release electromagnet II /

  <Desc / Clms Page number 24>

 RL2 which is currently open at contact 643.



   Referring now to the junction circuit and considering the moment when the relay 550 attracts, it can be seen that the latter at contact 551 disconnects the relay 530 at its contact at rest and that at its contact at work it closes the circuit comprising the top winding of relay 560 and jumper wires 308 and 309 going to the automatic office.

   At contact 552, relay 550 establishes the power supply circuit passing through the lower polarization winding of relay 560, at contact 553 it establishes its own blocking circuit by means of wire 574 which is earthed and independently of the contact 543, at contact 554 it closes a new supply circuit of relay 540 which comes from wire 574 earthed and passes through contact 544 to keep this relay attracted, at contact 555 it disconnects the earth of the starter wire 590 to remove the ground from the eighth level concacts of the vertical searcher benches and to open the circuit to the common start relay 819 if no other call is in progress, Relay 819 releases and disconnects the ground of the PS wire and the wire 638 which opens the primitive supply circuit of the searcher starting relay 640,

   this relay, however, is not kept attracted by means of the contact 615 which is earthed.



   When finder relay 610 is pulled, relay 920 to the operator position is also drawn into the following circuit: positive, contact 615, contact 642, lower winding of relay 640, contact 659, wire 639, winding lower of relay 920, negative. When relay 920 attracts it opens the circuit from relay 940 to contact 922. Relay ± 40 is delayed in operation as can be seen, for this reason it remains attracted for some time after this circuit has been opened.

   Relay 920 closes

  <Desc / Clms Page number 25>

 also the circuit which borrows the spring 922 and its contact at work, the contact 941 of the drawn relay 940, the wire 893, the normally closed contacts controlled by the spring 882, this circuit feeds the relay 860 of call signaling.



  When relay 860 pulls, it disconnects the operator equipment from lead wire 646 and connects that equipment through the make contact and spring 861 and normally closed contacts controlled by spring 871 at tone. invitation to transmit. A distinctive tone is therefore connected by wire DT through contact 861 of relay 860 and contact 851 of relay attracted 850 to the operator's receiver. This circuit also includes the NO contact 831 of the relay 830 which attracted when the operator connected her OH headset to the jack provided for this purpose.



   The relay 860 at contact 862 operates the delayed relay 870 interrupting the tone, this relay at contact 872 operates the relay 880 interrupting the signal.



  Relay 870 with spring 871 and its normally closed contacts momentarily interrupts the circuit bringing the tone to the attendant's receiver. To the working contacts of this spring it prepares the circuit which again connects the tone circuit to the operator's receiver when the second switch relay of signal 880 attracts. The attraction of relay 880 delayed on attraction to contact 881 again connects the current source DT to the operator's receiver, at contact 882 it opens the supply circuit of relay 860 and likewise closes its blocking circuit specific to wire 893 grounded. Relay 860 releases after a while and at contacts 861 and 863 cuts off the two short pulses of high frequency current sent to the operator's station.

   Relay 880 remains stuck on wire 893 until delayed run relay 940 releases, at which time time relay 880 also releases.

  <Desc / Clms Page number 26>

 



   When relay 940 releases, it disconnects the PS wire from the starter wire 638 at contact 944 without any effect at this time, as the relay 640 is held in the working position by the action of its lower winding. Relay 940 also disconnects ground from DS wire and M wires at contacts 943 and 943 to open the circuit for relays 826 and 822.



   When the upper winding of the polarized relay 560 is connected to the terminals of the junction wires 308 and 309 as a result of the pulling of the cut-off relay 550 in the junction circuit shown in fig. 6, the power supply circuit for relays 360 and 370 of the junction circuit in the automatic office closes as follows: positive, winding of relay 360, spring 351 and contact on, upper winding of differential relay 340, upper winding right side of the RC translator coil, contact at rest and spring 301, wire 308, loop described above and comprising the upper winding of relay 560 and wire 309, spring 302 and contact at rest, lower right winding of the translating coil RC, lower winding of differential relay 340, contact on and spring 552, winding of. relay 370, negative.

   To contacts 362 and 372, relays 360 and 370 connect the earth to wire 234 to keep relay 250 in the working position, relay 370 to contact 371 completes the supply circuit of relay 240 as follows: positive, contact 252, wire 235, contact 371, wire 229, contact 286, spring 243 and its contact at rest, reversing relay winding 240, negative. The differential relay 340 included in the circuit described for supplying the relays 360 and 370 is not attracting at this time because its two windings are in opposition. When relay 240 attracts, it first closes its blocking contact 244 to establish

  <Desc / Clms Page number 27>

 its own blocking circuit through its lower winding and through contact 252 which is earthed.



  At contacts 241 and 242, relay 240 sends the current back to the repeater of the prepayment station shown in fig. 2, for a reason to be given later. At contact 243, relay 240 opens its primitive supply circuit and closes the circuit of relay 320, tone switch, as follows: positive to wire 235 grounded, contact 371, wire 229, contact 286, spring 243 and its contact at work, spring 262 and its contact at work, contact 287, wire 233, spring 333 and its contact at rest, winding of relay 320 delayed in operation, negative.

   Relays 240 and 320 are delayed on pull to avoid connecting the special tone of the prepaid stations to the trunk circuit until the two short tone pulses through contacts 861 and 863 to the manual office have been received by the operator. When relay 320 attracts to contact 321 it removes the short-circuit placed on the upper winding of impedance coil 335, at contact 322 it opens the return circuit of the call tone to the calling subscriber. , on contact 323 it closes the circuit supplying relay 330.



   If the calling line is that of a prepaid extension, the special tone at these extensions is connected to the release wire of the trunk circuit to transmit this tone through the wire of the trunk to the attendant in the office. remote manual. This tone borrows the following circuit: winding of the tone machine T shown in fig, 1, terminals 32 and 31, capacitor, wire 498, contact at work and spring 35, brush 46, bank contact 54, release wire junction circuit 50, tone capacitor 144 'of FIG. 2, wire 201, selector and brush 205, bank switch 208, wire 247, spring 254 and contact at work,

  <Desc / Clms Page number 28>

 wire 246, lower winding of impedance coil 335, positive.

   The relay 330 attracts in the circuit comprising the wire 233 grounded and the contact 323, it locks on the wire 233, grounded, through the spring 333 and its contact at work, at the same time it opens the circuit of the delayed relay at attraction 320. At contact 331, relay 330 opens at another point the call return circuit coming from the current source IG and going towards the subscriber's station calling, at contact 332 it removes the shunt shunt on the lower winding of the impedance coil 335 so that the special tone of the prepaid stations can be induced in the upper winding of the impedance coil 335 before the delayed operating relay 320 has had time to release.

   While relay 320 is still drawn the tone induced in the upper winding of impedance coil 335 is transmitted through the straight windings of the RC translator coil, wires 308 and 309 of the junction and the wires. conversation leads from the remote manual office to the operator's station. Relay 330 also opens the call machine circuit at contact 334 and when slow-to-run relay 320 finally releases, the upper winding of impedance coil 335 is shorted to disconnect the special tone from the junction. prepaid stations.



   When the reversing key 240 reverses the direction of the current in the conversation wires 200 and 202 the polarized relays 128 and 132 attract. When relay 128 attracts it establishes its own blocking circuit through its winding lower than contact 163, it establishes the supply circuit of relay 127 delayed on release to contact 162, to contacts 160 and 164 it removes its upper winding and the upper winding of relay 133 of the bridge placed at the terminals of the

  <Desc / Clms Page number 29>

 wires from the junction circuit, it also disconnects the incoming wires 48 and 51 from the windings of the line relay 135 and the impedance coil 139 and extends them directly through the repeater to the windings of the relay 310.



  When the relay 127 attracts, at its contact 156 it establishes an additional blocking circuit of the preselector C, at the contact 155 it prepares the circuit for collecting the money at one point. Relay 132 is an electrically polarized relay set in such a way that it will attract its armature when the current is reversed in its upper winding, it will keep its armature attracted under the action of its polarization winding even if the circuit of its upper outer winding open later. Because if the direction of the current in its upper winding is brought back to normal, it will still attract its contact. When the relay 132 attracts, it opens the circuit of the relay 131 at one point, which prevents the latter from attracting at this time.

   The top winding of relay 132 is incorporated into the conversation circuit, but it is shunted by a non-inductive resistor which provides a flow path for the voice currents so that the output of the conversation circuit is not materially affected.



   Subscriber A is now connected to the operator position by the conversation wires as follows: from station A through line wires 11 and 12, 48 and 51, springs 160 and 164 and their contacts at work, the normally closed contacts controlled by the springs 172 and 173, the connecting wires 200 and 202, the brushes 203 and 204, the springs 211 and 212 and their contacts at rest, the springs 241 and 242 and their contacts at work , the working contacts of the springs 282 and 281, the springs 294 and 292 and their contacts at rest, the wires 219 and 218, the left windings of the

  <Desc / Clms Page number 30>

 RC translator coil, the right winding of the RC translator coil, the contacts at rest and the springs 302 and 301, the connecting wires 308 and 309, the normally closed contacts controlled by the springs 512 and 521,

   the springs 541 and 551 and their contacts at work, the translating coil RC of fig. 6, wires 572 and 571, finder brushes 602 and 601, contacts 612 and 611, contacts 653 and 651, response head and neck wires contained in cable 695, springs 971 and 972 and their contacts at rest, the head and neck wires leading to the operator's station.



  Supply current is supplied to the calling station through the windings of relay 310 while the operator's station supply current is supplied through the coil of relay 830 and earth connected to the terminal. induction coil associated with the attendant set.



   Checking the special dial tone for prepayment stations.



   -------------------------------------------------- ------------
In the event that the attendant does not perceive the special dial tone at prepaid sets and wishes to ensure that such a set is calling, she can do so by pressing the CRA reimbursement key (fig. 11) to refund the change. Under the action of the CRA key operation, the positive taken from the springs 1033 establishes the supply circuit of the relay 970 through the wire 1015.



  At the spring 1051 of the key the supply circuit of the relay 910 is prepared, it is not active at the moment because this circuit is open at the brush 605 of the searcher. At the key's spring 1032 a negative polarity of 110 volts is connected to wire 1017. When relay 970 attracts, at contact 972 it connects the negative coming from wires 1017 to wire 632 and then through contact 651, contact 611, finder brush 601, wire 571, upper right winding of

  <Desc / Clms Page number 31>

 the translator coil RC, from the winding of the reimbursement relay 520 delayed on attraction and from the contact 513 to positive.

   When relay 520 attracts, at contact 523 it opens the circuit of relay 510 at one point, at contacts 521 and 522 it connects a negative polarity to the two wires of the junction circuit 308 and 309. Connecting a negative polarity to both line wires 308 and 309 cause the imbalance of the differential relay 340 which attracts while the relay 370 is short-circuited, the result of which is that the latter releases. When relay 340 is attracted and relay 370 released, the reimbursement REF relay supply circuit closes as follows: contact 373 grounded, contact 342, wire 238, relay winding REF ', negative. At contact 341 the differential relay 340 establishes a blocking circuit for the release delayed relay 350 through contact 354.

   Releasing the relay 370 causes the contact 371 to open the blocking circuit of the relay 330 which releases. On contact 332 the relay 330 when it releases opens the shunt derivative on the upper winding of the impedance coil 335, on contact 334 it puts the wire RM to the ground to start the calling machine. When it draws the REF relay; to contact 299 connects negative polarity. of 100 volts in contact with the working springs 294 and 292, at the spring 297 it establishes the supply circuit of the relay 290 delayed on release. This circuit borrows the 234 grounded wire, the spring 288 and its contact at work, the contact 297, the coil of the relay 290, the negative.

   At contact 295, relay 290 earths wire 237 to keep relay 350 attracted, at contacts 292 and 294 it connects the negative polarity of 110 volts to the conversation wires which go to the subscriber's station. appellant. The application of this current on the conversation threads of the calling line

  <Desc / Clms Page number 32>

 causes the attraction of the polarized electromagnet forming part of the coin collecting mechanism to effect the redemption of coins deposited by the appellant.



   The attendant then restores the CRA key to the normal position, the result is that relay 970 releases and disconnects the negative polarity of 110 volts of wire 632 to release relay 520. When relay 520 releases, the contacts 521 and 522 it disconnects the negative of the two junction wires 308 and 309 and replaces the bridge comprising the upper winding of the polarized relay 560. When this bridge closes at the terminals of the junction wires 308 and 309 the relay 370 attracts again and the differential relay 340 returns its springs to the normal position because its two windings are equal and have opposite effects.

   As a result of the attraction of the relay 370 the circuit which has been described for the supply of the relay 320 is reestablished, it follows that this relay at contact 321 opens the short-circuit placed on the upper winding of the coil 335 of such that the tone connected to the lower coil winding can be induced into the upper coil and transmitted through the connecting wires 308 and 309 to the operator position.

   At contacts 342 and 373 the circuit of the REF relay is open, this relay releases and disconnects the so-called "money refund" polarity of the calling line at contact 299, it also opens the circuit of relay 290 at contact 297. When the relay 290 releases after a certain time it opens the bridge placed at the terminals of the calling line and reconnects the relay 310 which attracts again. At contact 295, relay 290 opens the blocking circuit of relay 350 but the latter being delayed on release will remain attracted until relay 310 establishes its contact 311, it follows that relay 350

  <Desc / Clms Page number 33>

 do not relax during this time.

   Relays 320 and 330 pull up as previously described to transmit the special tone to the prepaid station over the trunk wire the moment both relays are pulled on and before relay 320 has fully released. The circuits are therefore returned to the state they were in when the call was first received at the operator position and the operator can get in touch with the calling subscriber at the start. to request the desired number. The attendant can now ask the caller to deposit the coins required for payment of the call or she can wait until the connection has been established with the called subscriber before asking. payment of the amount due.



  The attendant listens to the special tone at the prepayment station which is emitted by the mechanism of this station in the well-known manner when the required coin is deposited.



   In the lower right corner of fig. 8 the transmitter circuit SL and the transmitter-recorder RS shown in the dotted rectangles operate identically to that of the circuits of the transmitters and the transmitter-recorder described in Belgian Patent N '325258 ¯ , filed September 16, 1936. The transmitter circuits of the mentioned case include a pair of circuits comprising a finder and a selector, the finders are used to select a particular finder circuit such as that shown in Figs. 7 and 8 put into service by the operator while the selector of these transmitter circuits selected a free transmitter-recorder.

   Each operator position is provided with a set of transmission keys by means of which the transmitter-recorder can be put into service to transmit: digits which correspond to the particular transmission keys which have been activated. When the 830 relay draws at the moment

  <Desc / Clms Page number 34>

 where the attendant pushes the plug of her OH equipment into the appropriate jack, wire 697 is grounded to contact 832. When relay 850 has drawn to ground wire 891, one of the transmitting circuits shown in the dotted rectangle is activated to select the particular finder circuit to use, in this case the circuit shown in figs. 7 and 8.

   The circuit for grounding wire 696 borrows spring 853 grounded wire and its working contact / 891, spring 921, and spring 931.



   When the relay 650 of the finder circuit shown in fig. 7 was attracted, this relay at contact 660 connected the marking negative to wire 774 to mark the finder circuit shown in fig. 7 and 8 as the finder circuit which must be selected for the transmitter circuit. This marking circuit is as follows: relay winding 1130, vertical shaft springs 1151, wire 793, contact 660, wire 690, contact 714, wire 774 which ends at the researcher bench test contacts accessible to the circuits of 'transmitter.

   The finder circuit finder operates until this negative is found, the transmitter circuit finder SL then performs the switching and when the associated switches find a free transceiver RS l ' operator can activate the digit keys in accordance with the number of the called subscriber.



   The relay 1130 attracts in the circuit which has just been described, at contact 1131 it opens at one point the circuit of the rotation electromagnet RM3, at contact 1132 it prepares the circuit of the electromagnet at one point of ascent at the same time that it prepares its blocking circuit through its lower winding, at contact 1133 it opens at one point the circuit of the release electromagnet RL3 and at contact 1134 it connects a positive by through the springs

  <Desc / Clms Page number 35>

 cam switch 1161 to the lower winding of line relay 1110.



  When the bridge closes on the wires 772 and 771 in the transmitter, the relay 1110 draws into the circuit comprising the wires 771, 772, 791 and 792, the springs 1141 and 1142 and their contacts and contacts at rest, the windings / lower of line relay 1110, negative and positive respectively. At contact 1111, relay 1110 completes the supply circuit from relay 1120 to contact 1145 earthed. At contact 1121, relay 1120 connects the selector test brush to the active winding of the electrically polarized relay, at contact 1122 it grounds the junction release wire 793, at contact 1123 it prepares a another point is the ascending electromagnet circuit VM3 and the lower winding of relay 1130, at contact 1124 it completes the circuit passing through the lower polarization winding of relay 1140.



  Relay 1140 is not attracting at this time, it only does so when current is flowing through its top energizing winding in the desired direction. The operation of the line relay of the selector and of the release relay occurs as a result of the lowering of the starting key and the actuation of the digit keys, as explained in the Belgian Patent. referred to above. The transceiver transmits the digits of the called number on wires 771 and 772.



   Under the action of the impulses transmitted on the wires 772, 771 and 792 and 791 by the transceiver, the line relay 1110 releases at each interruption of the current, at contact 1111 it completes the excitation circuit of the electro - VM3 ascent magnet and the relay blocking circuit attracted 1130 as follows: contact 1145 earthed, spring 1111 and its contact at rest, contact 1123 and its contact at work, contact 1132, electro winding magnet

  <Desc / Clms Page number 36>

 VM3, negative. and lower winding of relay 1130, negative. The ascension electromagnet raises the selector brushes, 1171 to 1173 inclusive, by one step for each pulse received so as to bring these brushes to the desired level.



  The relay 1130 being a relay delayed on release remains attracted during the period of sending the pulses, The line relay 1110 is kept attracted after the first series of pulses, it therefore opens the circuit passing through the lower winding of the series relay 1130 for a time sufficient to allow the release of the latter.



   At the first step of ascent of the selector brushes, the vertical shaft springs 1151 open the primary supply circuit for relay 1130 .. the vertical shaft springs 1152 prepare the circuit of the rotation electromagnet at one point. RM3 and vertical shaft springs 1153 at one point prepare the circuit for the release solenoid RL3.



   When relay 1130 releases contact 1134 substitutes the earth taken at contact 1124 for the earth taken at cam springs 1151 for the supply of the lower winding of line relay 1110, at contact 1133 it prepares a another point is the circuit of the release electromagnet RL3, at contact 1132 it opens its own circuit at one point and the circuit of the ascending electromagnet VM3, at contact 1131 it establishes the circuit of the RM3 rotation electromagnet.

   This circuit is as follows: positive, contact 1145, spring 1111 and its contact on, contact 1131 vertical shaft springs 1152, switch contact 1154, winding of the rotation electromagnet RM3, negative. The rotating magnet attracts in this circuit and turns the selector brushes one step at each pull. At about the end of its attraction the rotating electromagnet at its switch contacts 1154 opens its own circuit

  <Desc / Clms Page number 37>

 which releases the rotation electromagnet RM3 to complete its circuit again at switch contacts 1154.

   The rotating electromagnet continues to function as a buzzer and rotates the selector brushes until the selector test brush 1173 encounters a negative connected test bench contact.



   When selector test brush 1173 encounters a bank contact of this level connected to negative, relay 1140 draws into the following circuit: positive, contact 1122,. upper excitation winding of relay 1140, contact 1121, selector test brush 1173., bank contact connected to negative. When relay 1140 comes to springs 1141 and 1142 it disconnects the windings of line relay 1110 from wires 791 and 792 and connects these wires through the working contacts of these springs to brushes 1171 and 1172 of the selector. which are now engaged on the bench contacts terminating a free junction.

   At contact 1143, relay 1140 connects the upper excitation winding in a momentary short circuit and also connects test brush 1173 directly to the release wire 793 of the incoming junction. At contact 1144, relay 1140 completes its blocking circuit specific to contact 1122 earthed as well as the one which will keep it attracted when earth is sent by the following selector via the test brush 1173, to this contact 1145 it opens the circuit of relay 1120 delayed on release. Line relay 1110, on releasing, opens the circuit of relay 1120 at another point. Relay 1120 does not release until a positive has been sent by the next switch to keep relay 1140 pulled as. it has been described previously, owing to its special characteristic.

   The positive of contact 1122 is therefore not removed from wire 793 until the positive coming

  <Desc / Clms Page number 38>

 of the previous switch has been returned to this wire through the test brush 1173 and the contact 1143. The remainder of the connection is established by means of selectors and connectors in the well known manner, so it is not necessary to give detailed explanations. Under the action of the last digit transmitted by the transceiver, the connector functions to engage its brushes on the contacts of the called line.

   If the called line is free, the connector rings the called subscriber in the well-known manner, when this subscriber answers one of the relays of the connector attracts to reverse the direction of the current in the wires of the selection train and in the sons 791 and 792,
If we now return to the finder circuit of figs 7 and 8 and if we consider the moment when the transceiver has completed the transmission of the emitted digits, a ground connected to wire 773 to draw the relay 710 under the action of its lower winding.

   When the relay 710 attracts, at contact 716 it keeps the occupancy lamp BL on, at contact 715 it earths wire 793, to release the junction, which ends at the selector, at contact 714 it opens the earthed circuit which ends in the emitting circuit, at contact 713 it completes its own blocking circuit through its upper winding, a resistor and the negative; contact 712 it connects the left windings of the RC translator coil to the conversation wires of the finder circuit, at contact 711 it connects the conversation wires 791 and 792 to the right windings of the RC translator coil and earths the relay 730 through wires 791 and 792.

   When relay 710 to contact 711 connects the excitation winding of relay 730 through wires 791 and 792 this relay pulls only if current is flowing in the desired direction in its upper excitation winding.

  <Desc / Clms Page number 39>

 



  In the present case, relay 730 attracts only during the time when the negative is connected to wire 791 and the positive to wire 792. When relay 730 attracts, at contact 731 it prepares the circuit which lights the call lamp and passes through the contacts at rest of the springs 746 of the key. When the called subscriber answers the polarities are reversed on the line wires 791 and 792 in the well known manner, the result is that the relay 730 releases since the current flowing through its excitation coil has an effect opposite to that. which runs through its lower winding. On contact 731, relay 730 opens the call supervision lamp ignition circuit.



   If the called line is busy or if the called subscriber does not answer, no polarity reversal occurs on wires 791 and 792, the result is that the polarized relay 730 remains engaged and that the circuitry of the call supervision lamp is not switched off.



   The attendant, when making a call sent by a prepaid set of this type, keeps her K2 conversation key activated until the called party answers or until the busy tone is returned by the connector to the telephone. 'operator.



   If the called line is busy the busy tone will be sent back to the connector wires and selector brushes 1171 and 1172 and from there through wires 791 and 792, contact 711 and the right coil winding. transmitter RC, from where it is induced in the left winding of the RC translator coil and returned through contact 712, wires 681 and 682, the working contacts of springs 652 and 654 of relay 650 for connection of the operator, the call head and neck wires 633 and 635, the springs 992 and 991 and their contacts at rest, the head and neck wires 644 and 646 to end at the operator's station.

   The op-

  <Desc / Clms Page number 40>

 Missing woman informs the subscriber of the prepaid set that the requested line is busy and repays the deposited change by activating the CFA answer and refund key, Following the activation of this key Relay 970 draws in the manner described previously to connect the negative at 110 volts to wire 632 and cause the pull of relay 520. As described previously, the attraction of relay 520 connects the negative through contacts 521 and 522 to the wires of the junction line 308 and 309 to cause the attraction of the differential relay 340 and to release the relay 370 of the circuit junction shown in FIG. 4.

   As previously described, the attraction of the differential relay 340 and the release of the relay 370 causes the attraction of the reimbursement relay REF of FIG. 3 and the latter causes the attraction of the relay 290 to connect the negative to the two wires of the calling line to reimburse the caller the change he has deposited.



   If it is assumed that the called subscriber instead of being busy has answered the call, the attendant activates the CCA cash-in and response key to cause relay 970 to be drawn through the intermediary of the springs 1023 of the key and wire 1015.



    At the key springs 1021 a circuit is prepared for pulling the relay 910, this circuit is not active for the in- at the key springs 1022 the negative polarity of 110 volts is connected to the wire 1018 and since the relay 970 is attracted at this moment this polarity borrows the wire 634, the spring 971 and its contact at work, the spring 653 and its contact at work, the contact G12, the brush 602, the wire 572, the right winding lower part of the RC translator coil, relay 510 to lead to grounded contact 523.

   When relay 510 attracts, at contact 513 it opens at a point

  <Desc / Clms Page number 41>

 the circuit passing through the relay 520, to the contacts 511 and 512 it connects the positive to the two junction wires 308 to cause the attraction of the differential relay 540 and the release of the relay 360.



   Relay 360 drops because it is shorted by the positive coming from wire 308 and differential relay 340 is pulling right now because its upper winding is shunted as well which allows the lower winding to energize the differential relay. At contact 341, relay 340 keeps the circuit of the release delayed relay 350 closed, at contact 343 it closes the circuit of the collection relay COL of fig. 3 via contact 363 of relay 360 and wire 239. At contact 298 the relay COL prepares the circuit connecting the positive of the battery to the calling line and at contact 296 it establishes the circuit at - pulling of relay 290. When relay 290 attracts, it connects the positive to the calling line by means of the working contacts, springs 292 and 294.

   Connecting a positive to both wires of the calling line causes the polarized relay of the coin collecting mechanism associated with the calling line to be drawn to cause the subscriber's deposited coins to be cashed in in the well known manner.



   After the cash has been collected, the operator replaces the conversation key K2 which prepares the circuit of the response supervision lamp AS to the springs 741 of the key, it opens the circuit of the connection relay 650 to the springs 744 and 745 and prepares the circuit from the supervision lamp CS to the springs 746. In the operator position, placing the CCA key in the normal position opens the circuit of relay 970 which consequently releases and the setting in the normal position of the key. K2 conversation key opens relay 850 circuit.

   When relay 850 releases at contacts 851

  <Desc / Clms Page number 42>

 and 852 it prepares the monitoring circuit and the relay circuit 840, to the spring 855 and its contact at work it disconnects the positive of the wire 891 and of the wire 696 which goes towards the circuit of the emitter, at the contact at the resting the spring 85 @ it grounds the test lead 753. At contact 854 the relay 850 disconnects the positive of the lead 892 to open the circuit of the relay 940 which therefore releases.

   On contact 941, relay 940 opens the blocking circuit of relay 880 which releases, on contact 942 it disconnects the positive of wire DS to open the blocking circuit of the selection relay which has drawn into the distributor DIS, at contact 943 it disconnects the positive from wire M to open the circuit of relay 822, at contact 944 it disconnects the starting wire 658 from wire PS which leads to the distributor.



   When relay 650 releases when the key K2 is restored to the normal position at contacts 651 to 654 inclusive, it disconnects the searcher circuit from the attendant position and connects the calling and called subscribers to the conversation wires, to the contact 655 opens the circuit of relay 720, at contact 656 it disconnects wire 637 from the upper winding of relay 710, at contact 657 it opens its own blocking circuit at one point, at contact 658 it disconnects the wire 638 of the upper winding of the start relay 640, at contact 659 it disconnects wire 639 from the lower winding of relay 640 which opens the circuit of relay 920 of the equipment of the operator position, at the contact 660 it opens at another point the circuit connecting the selector release wire 793 to the transmitter circuit.

   When relay 920 releases all relays in the operator position have returned to their normal position ready to serve another call. The relay 640 does not attract when the key K2 is returned to the rest position because this relay remains attracted

  <Desc / Clms Page number 43>

 through the earthed contact and under the action of its lower winding. The conversation circuit between the caller and the called party comprises the conversation wires and the translator coil. At any time during the conversation the operator can monitor it by activating the listening key K1 in fig. . 7. As a result of the lowering of the key k1 the head and neck wires 644 and 646 are connected to the conversation wires 681 and 682 by means of the springs 675 and 677.

   To the springs 676 the positive connected through the wire 645 and the contact 852 causes the attraction of the relay 840 which to the contacts 841 to 843 inclusive connects the operator's station to the RC translator coil of the pin 9 to allow the operator to follow the conversation. Following the resetting of the listening key of FIG. 7 relay 840 releases to open the circuit leading to the operator's station, at contacts 675 and 677 the researcher conversation circuit is disconnected from the operator's conversation circuit.



   End of communication supervision.



   ------------------------------------
After the conversation and the fact that the called subscriber hangs up his receiver the connector supply relay releases in the well-known manner and reverses the polarities on the conversation wires and through the upper winding of the polarized relay 730. The relay 730 attracts when the direction of the current changes, it closes its contact 731 to switch on the call supervision lamp CS via the key's 746 springs, which warns the operator that the subscriber called. has hung up.



   When the caller hangs up his receiver, relay 310 of FIG. 4 releases and at contact 311 opens the circuit of the delayed release relay 350. At contacts 351 and 352 the relay 350 reverses the polarities on the junction wires.



  He/

  <Desc / Clms Page number 44>

 308 and 309 to cause the release of the polarized relay 560 shown in fig 6. At contact 353 the relay 350 disconnects one of the multiple connections to the ground of wire 254, at contact 355 it disconnects one of the multiple connections to the ground of wire 247 release of the junction. When the polarized relay 560 of the junction circuit shown in. fig. 6 releases as a result of the reversal of the polarities on the junction wires 308 and 309 this relay at contact 561 connects a positive through contact 552 to wire 573 and from there through brush 603, wire 683 , key springs 741, filament of the AS response supervision lamp to negative.

   The AS lamp lights up in this circuit to draw the operator's attention to the fact that the caller has hung up his receiver. If desired, the operator at this moment can activate her conversation key K2 again to connect to the researcher circuit and can then activate the CCA collection key to cause the cash to be cashed in the way that has been described above if it is desired that this operation be carried out only when the two subscribers have hung up their receivers.



   Reminder.



   In the event that the operator wishes to call back the caller after he has hung up his receiver, she activates his conversation key K2 to attract the relay 650 which connects its position to the searcher circuit in the manner which has already been described. . The operator activates her RIA key to cause the attraction of relay 970 through contacts 1014 earthed and wire 1015, to contacts 1012 and 1013 he connects the earth and the generator to wires 1018 and 1017 and by through contacts at work

  <Desc / Clms Page number 45>

 from the springs 971 and 972 to the wires 634 and 632 which at this time are connected to the finder brushes 602 and 601 through the closed contacts 653 and 651.

   This ringing current application extends from the finder's brushes 601 and 602 to the translator coil RC of the junction circuit of FIG. 6, it then borrows the junction wires 308 and 309, the winding of the alternating current relay 380, the capacitor and the contact 391. The alternating current relay 380 draws under the action of the inrush current. and puts the release wire of junction 247 to earth at contact 381, at contact 382 it places wire 248 to earth to attract relay 210. When relay 210 attracts, at contact 213 it places wire 247 to earth, to contacts 211 and 212, it connects the positive and the generator GEN on the existing connection to activate the ringing of the calling subscriber and call him back.

   The operator can ring as often as she wishes, after having established the ringing circuit she will return the RIA key to the normal position to release the relay 210 and disconnect the inrush current of the calling line.



   Releasing the connection.



   ---------------------------
If it is now assumed that the attendant wishes to release the connection that has been established, after observing that the call supervision and answer lamps are on, she activates her conversation key K2 to provoke the pull. relay 650, it then actuates the RLC key to cause the release of the automatic switches of the switching train extending to the line of the called station.



  Following the actuation of the RLC key, the springs 1071 earth the wire 637 to attract the relay 930 - and to release the relay 710 by short-circuiting the upper winding of this relay. At contacts 1072 the earth is

  <Desc / Clms Page number 46>

 connected to wire 1016 to attract relay 990. Pulling relays 950 and 990 from the operator position has no effect at this time. In the circuit of the seeker of fig. 8 relay 710 releases because its upper blocking winding is short-circuited by the earth coming from the operator position and this relay on contact 711 opens the circuit of the automatic switches to cause the release of these from the switch. well known way.

   At contact 713, relay 710 opens its own blocking circuit at one point, at contact 714 it prepares the circuit which ends in the transmitter circuit at one point, at contact 715 it disconnects the earth of the release wire of junction 793 , at contact 716 it cuts one of the earth connections of the occupation lamp BL. When the earth is removed from the junction release wire 793 and the automatic switches in the office have returned to the rest position the relay 1140 of the selector shown in fig, 12 releases. On contact 1145, relay 1140 establishes the circuit of the release electromagnet RL3 as follows: positive, contact 1145, spring 1111 and its contact at rest, contact 1123 and its contact at rest, contact 1133 and its contact at rest, vertical shaft springs 1153, release solenoid coil RL3, negative.



  As a result of the attraction of the release electromagnet, the selector brushes are returned to the normal position and the vertical shaft springs are returned to the positions shown in the drawings. The selector in fig. 12 returns to idle shows the map and can be used for other calls.



   In order to release the link going to the caller's station, the operator actuates the RLA key to ground wire 1015 to the springs 1042 of the key, which causes the attraction of the relay 970 to the contacts 1041 he puts

  <Desc / Clms Page number 47>

 ground wire 639 to draw relay 920 and short circuit the lower blocking winding of relay 640. Operation of relay 920 in the operator position has no effect at this time, but the relay 640 releases as a result of the short circuit placed on its lower blocking winding.

   At contact 661, relay 640 disconnects the earth of the occupancy lamp BL to switch it off, at the spring 643 and its contact at work it disconnects the earth of the brush 604 and opens the blocking circuit of the switching relay 610, of this fact this one relaxes. At the spring 643 and its contact at rest, the relay 640 establishes the circuit of the releasing electromagnet RL2 of the searcher by means of the vertical shaft springs 674, therefore the brushes return to the rest position of the well known way. When the brushes reach their normal position the vertical shaft springs 674 open the circuit of the releasing electromagnet and the vertical shaft springs 671 at one point prepare the primitive supply circuit for relay 640.

   Releasing relay 610 disconnects the searcher brushes from the conversation wires of the connection circuit to contacts 611 and 612, at contact 617 it prepares at one point the primitive supply circuit of the ascent electromagnet VM2.



   The finder circuit finder is therefore returned to the rest position and can be used for other calls.



   As a result of the disconnection of the earth of the brush 604 following the release of the start relay 640, the blocking circuit of the cut-off relay 550 of the junction circuit is opened, as a result this relay releases after a short instant. At contact 551 the relay 550 reconnects the alternating current relay to the terminals of the junction wires 308 and 309, at contact 552 it disconnects the earth of the winding

  <Desc / Clms Page number 48>

 lower bias of relay 560 and ground wire 573 to turn off the seeker circuit response supervision lamp.

   Disconnecting the earth from wire 574 also opens the blocking circuit of relay 540, which at contact 541 opens the bridge placed at the terminals of junction wires 308 and 309, at contact 542 it disconnects the earth of wire 583 to make this junction circuit accessible by the selectors and prepare the circuit of the cut-off relay 550.



  At contact 545, relay 540 opens at one point the primary supply circuit of relay 550, at contact 544 it opens its own blocking circuit at one point, at contact 545 it opens at one point the starter wire 590. Because relay 550 is delayed on release releases after releasing relay 540, as a result, earth is not connected to the starter wire at contact 555 because the starter relay 540 is released and opens the starter wire circuit. at contact 545. When relay 540 releases, at contact 541 it opens the bridge placed on junction wires 308 and 309 and relays 360 and 370 release. When relay 360 releases, at contact 362 it disconnects one of the multiple ground connections of wire 234, at contact 363 it grounds wire 245.

   When relay 370 releases, at contact 371 it opens the blocking circuit of relay 330 which consequently releases, at contact 372 it disconnects the earth of wire 234 to open the circuit of the delayed release relay 250. When the relay 250 delayed on release releases, at contact 252 it disconnects the earth of wire 255 to open the blocking circuit of the reversing relay 240 and the blocking circuit of the relay 260 and to connect the negative through the winding polarization element from relay 230 to wire 215 for releasing the junction.

   At spring 254 and his contact at work on

  <Desc / Clms Page number 49>

 relay 250 disconnects the grounded wire 246 from the junction release wire 247 which opens the blocking circuit of relay 280 and releases the selector of fig. 3, the repeater of the prepaid station, shown in fig. 2 and the preselector of FIG. 1. When relay 280 releases, at contacts 281, 282, 284 and 285 it disconnects relay 300 from the bridge placed on the calling line and substitutes the upper windings of relays 220 and 230 placed at the terminals of wires 217 and 257. leading to the incoming selector of fig. 5.



  At contact 283, relay 280 opens at one point the call return circuit, at contact 276 it connects the negative through resistance as well as a direct negative, through the winding of relay 280, to the junction release wire 247 by means of the contacts at rest of the spring 254 to mark this junction circuit as free for the other selectors which have access to it.

   At contact 279 the positive is disconnected from wire 249, as a result of releasing relay 280, to open the circuit of relay 390. ' At contact 391, relay 390 when released, opens the circuit of AC relay 380 at one point, at contact 392 it connects the negative through the bias winding of relay 230 to the free wire 215. junction ration of the incoming selector, at contact 393 it opens at one point the circuit of the starting wire 256 of the calling machine. When relay 240 releases, at contacts 241 and 242 it returns the conversation wires to the normal position, at contact 243 it prepares its original supply circuit at one point, on, at contact 244 it opens at one point its own blocking circuit.

   All the relays and all the junction circuit devices shown in fig. 3 and 4 have now returned to their normal position and can be used for further calls.



   As a result of the disconnection of wire 247 from ground

  <Desc / Clms Page number 50>

 junction release, the selector shown schematically in fig. 5 releases in the known manner and disconnects the earth from the junction release wire 201. When ground is disconnected from junction release wire 201 the lower bias winding circuit of relay 132 is open, the blocking circuit of relay 134 is open, the blocking circuit passing through the lower coil of the relay polarized 128 is open, therefore these relays drop.



  When the relay 134 releases, at the contact 130 it prepares at one point the branch circuit mentioned above. With the earth removed from the junction release wire 201, the relays 128 and 132 of the repeater of the prepayment station release. When relay 132 releases it prepares the circuit of relay 131 for contact 175. When relay 128 releases it opens the circuit of relay 127 delayed in operation, but before this relay has had time to release a pulse of current is sent in the following circuit: positive, spring 152 and its contact at rest, contact 157, winding of the slow pull relay 125, negative.



  When the relay 125 attracts, it places at contact 146 an additional earth on the junction release wire 50 which extends towards the preselector C. As another consequence of the pulling of the relay 125 it can be pointed out that springs 145 and 144 and to their working contacts the two constituents of the line of station A are connected to the negative "collection", by the intermediary of the spring 155 and its contact at work, the contact 177 and the winding 'of relay 140.



  When this circuit is closed, the current flows from the negative "collection" to the earth, through the winding of the relay 140 and the polarized electromagnet of the prepayment station in series, which attracts the relay 140 and the electromagnet

  <Desc / Clms Page number 51>

 polarized cash collection. When the relay 140 attracts, on contact 195 it closes the circuit of the relay 126 delayed in operation. When the relay 126 attracts, on contact 150 it closes the blocking circuit of the relay 127, which being delayed on release has not yet released, it closes the circuit of the relay 131 which reverses the wires 200 and 202 with respect to to the wires of the calling line, at contact 152 it connects the wires of the incoming line to earth through the capacitor.

   Usually the polarized electromagnet will respond directly to the action of the current coming from the collection battery, it will attract to operate the collection of the deposited coins and to return the complete coin collection mechanism to the normal position. instantly at the same time as it disconnects from line wire 12.



   However, it sometimes happens that the armature of the polarized electromagnet will remain stuck, the relay 133 is provided to ensure the collection of the currency in this case.



  In the present case as the change has already been cashed, this operation has no effect at the time considered but will however be described in such a way that the operation of the repeater of the prepayment station can be known when local calls are established. Switch I causes the armature of relay 133 to vibrate rapidly which interrupts the circuit of the negative polarity "cashing" to ensure the cashing of the change and to prevent the polarized electromagnet of the mechanism. cashing does not come to stick.



  However if the armature of the polarized electromagnet continues to stick the relay 127 remains attracted. In this case, since the change has been collected beforehand by the operator, the circuit of the polarized electromagnet of the mechanism of the prepayment station opens and it follows that the relays 140

  <Desc / Clms Page number 52>

 and 126 do not attract, since relay 126 does not attract in the present case, relay 127 does not remain attracted in its blocking circuit, the result of which is that the latter finally releases. When the relay 127 releases it opens the circuit of the relay 125 at contact 157, at contact 156 it disconnects one of the earth connections of the junction release wire 50.

   When relay 125 releases at contact 146 it disconnects the ground of the junction release wire and causes the release of relay 25 from line 50 which releases the preselector in the well known manner. All the equipment that was used to make a call from station A has returned to the idle position and can be used for other calls.



   Call from a prepaid set connected to a manual office -------------------------------------- -------------------- to an automatic station.



   -------------------------
It will now be assumed that the subscriber A1 having a prepaid station in a manual network as shown in FIG. 14 wishes to get in touch with a subscriber A having a prepaid station such as that shown in FIG, 1.



  When subscriber A1 to make a call picks up his receiver and deposits the change required to close the springs 1309 of the well known way, the line relay 1310 draws in the following circuit: positive, winding of the. polarized electromagnet 1308 for collecting coins, the springs 1309 on the one hand, the lower conversation wire and on the other hand the microphone T, the fork springs and the upper winding of the induction coil, the upper conversation wire, and then in parallel the contacts 1331 and 1332 and their contacts at rest, the spring 1321 and its contact at rest, the upper winding of the line relay 1310, the negative.



  The relay 1310 attracts under the action of its upper winding, alone and through the two conversation wires in parallel.

  <Desc / Clms Page number 53>

 



  Aucontact 1311 the line relay 1310 completes its own blocking circuit which borrows the positive, its lower winding, the contact at rest and the spring 1322, the contact 1311 and the upper winding, the negative. At contact 1312, relay 1310 connects cut-off relay 1320 to the contact of bank 1304 via wire 1344 so as to mark this line as calling in the researchers' benches. At contact 1313, relay 1310 puts wire 1287 to earth to mark this line for occupancy for switches which have access to it.

   At contact 1314 the relay 1310 disconnects the earth of the contact 1303 of the researcher bench and at the contact 1315 earths the starter wire 1316 to attract the relay 819 and to mark the particular vertical bank contact corresponding to the level on which the manual prepayment set is connected, in this case it was assumed that it was the ninth, which marks in the researcher bank the group to which the calling line belongs. When relay 819 attracts, at contact 818 it turns on all the lamps L1 in all operator positions and at contact 846 it grounds the common starting wire CSC.



   In the case where the operator of one of the positions is free, she actuates the key K2 of a free seeker circuit in the manner which has been described previously. If we assume that the researcher circuit shown in Figs. 7 and 8 is the circuit whose key K2 has been activated, then the connection relay 650 draws into the circuit test lead 753 in the manner previously described. Since the operation from this point on will be the same as that described previously, only a brief description will be given here. As a result of the operation of the connection relay 650 the operator position is connected to the searcher circuit and the relay 850 draws in series with the lower winding

  <Desc / Clms Page number 54>

 relay 650.

   At contact 854, relay 850 closes the circuit of relay 940, therefore this relay at contact 942 puts the distributor selection relays in service through the DS wire, at contact 943 it marks the position represented, as being the one that responds ., at contact 944 it connects the PS wire to the starter wire 638. The distributor selection relays operate in the manner previously described until the relay 826 at contact 844 closes the circuit of relay 822. At contact 845 the Relay 826 connects the CSC grounded wire at contact 846 to the PS wire which is connected to the starter wire 638 which completes the circuit of relay 640 of the finder circuit. In the manner previously described, the starter relay 640 locks up and operates the ascending electromagnet.

   The finder ascender electromagnet operates until the vertical test brush 607 engages the marked vertical bench contact to which the starter lead terminates. When the seeker's vertical test brush meets the contact of the grounded vertical bench, relay 620 draws as before and connects the control circuit to the rotation electromagnet.



   The seeker rotating electromagnet is stepped to rotate the brushes until test brush 304 finds the seeker bench contact marked with a "call" polarity. When the brush 604 engages on the contact 1504 of the researcher's bench, the cut-off relay 1320 and the switching relay 610 attracts in series as follows: positiî, spring 343 and contact on, upper coil of excitation of the switching relay 610, 604 brush, 1304 contact, 1344 wire, 1512 contact, cut-off relay winding 1 @ 20, negative.

   At contacts 611 and 612, relay 610 at one point closes the conversation circuit between the calling subscriber

  <Desc / Clms Page number 55>

 and the operator position, at contact 615 it completes the blocking circuit through the lower winding of the starter relay 640, at contact 616 it earths the searcher brush 604 so that the cut-off relay 1320 attracts to background. and to mark this line as being occupied in the researchers' benches, at contact 617 it opens the blocking circuit of relay 620 which consequently releases.



   At contact 1321, relay 1320 connects the lower wire to the positive wire of the calling line to the lower winding of line relay 1310, at contact 1322 it opens the local loop placed at the terminals of relay 1510, at contact 1323 it closes its circuit blocking, at contact 1324 it opens the circuit of the lower winding of relay 1520 and prepares at one point the subsequent earthing circuit of the junction release wire 1287, at contact 1325 it disconnects the earth of the starter wire 1316 to release relay 819 in the event that no other call has been made.



   The attendant can currently speak with the subscriber of set A1 in the following circuit: line 1341 and 1542, bank contacts 1301 and 1502, brushes 601 and 602, contacts 611 and 612, contact 651 and 653, wires 632 and,? 34, spring 971 and '972 and their contacts at rest, conversation wires 646 and 644 associated with the operator's station. The supply current to the calling subscriber is supplied through the windings of the line relay 1310.



   It will now be assumed that the subscriber A1 informs the operator that he wishes to be put in touch with a subscriber A of the remote automatic office and that the operator acts on the digit keys to store the number in the. transceiver, after which the sender is switched on to transmit the digits of the called number. The sending of the impulses from the transceiver is carried out

  <Desc / Clms Page number 56>

 sons 772 and 771 to sons 791 and 792 as previously described. The selector shown in fig. 12 operates in the manner previously described, but in this case, since the call must be extended to the remote automatic office, the selector operates to select one of the trunk circuits to which a free trunk in that office terminates.

   If we assume that the junction circuit shown in fig. 6 is the junction circuit selected by the selector the selector relay 1140 draws into the following circuit: positive, contact 1122, secondary energizing winding of switching relay 1140, contact 1121, brush 1173, bank contact 1187, wire 583, spring 542 and its contact at rest, winding of cut-off relay 550, negative.



  To contacts 1141 and 1142, relay 1140 connects conversation wires 791 and 792 to wires 581 and 582 which are connected to wires 308 and 309. At contact 1143, relay 1140 earths brush 1175 to make the draw fully drawn. the cut-off relay 550 and to mark this junction as occupied for the other selectors which have access to it. When relay 550 attracts, at contact 551 it disconnects the upper winding of the alternating current relay from the bridge placed at the terminals of the junction wires, at contact 553 it grounds wire 574 to mark this junction circuit as being occupied, at contact 554 it opens the circuit of relay 540 at one point, at contact 555 it disconnects the positive to prevent the starter wire 590 from being grounded.



   When the selector makes the connection and places the transceiver pulse springs across the junction wires 308 and 309 the relays 360 and 370 draw in the following circuit: positive, line relay winding 360 of the junction, normally closed contacts checked by contact 352, lower coil of the relay

  <Desc / Clms Page number 57>

 differential 340, lower right winding of the RC translator coil, contact at rest and spring 302, wire 309, wire 582, brush 1172, contact on duty and spring 1142, wire 792, wire 772, impulse springs of the transmitter -register, wire 771, wire 791, spring 1141 and contact on, brush 1171, wires 581 and 308, spring 301 and contact at rest, upper right winding of the RC translating coil,

   differential relay top winding 340, springs normally closed controlled by spring 351, junction line relay 370 winding, negative.



   When the relay 370 attracts, at contact 372 it places wire 234 to the ground to attract relay 250. When relay 360 attracts to contact 362 it likewise places wire 234 to earth and to contact 361 it connects the upper winding of relays 220 and 230 in bridge on the windings of the line relay (not shown) of the incoming selector SEL2 in fig. 5.



  This selector is identical to the selector shown in fig, 12 and should not be described further. When relay 250 attracts, at contact 251 it prepares at one point the circuit of relay 270 delayed for operation, at contact 252 it grounds wire 235 to power the polarization winding of relay 230 and to connect a earth to the junction release wire 215 to attract the incoming selector relay SEL2 in fig. 5 corresponding to relay 1130 of fig, 12 via contact 392 and wire 215.

   At contact 253, relay 250 prepares at one point the blocking circuit of relay 220 delayed on release which is active during the period of sending the pulses, at contact 254 it opens the circuit of relay 280 and earths the wire junction release 247 via contact 332 and wire 246 to mark this junction circuit as busy for all selectors that have access to it. ,

  <Desc / Clms Page number 58>

 
Closing the bridge in the junction circuit at contact 361 causes the attraction of relay 220 as follows:

   positive and negative through the incoming selector line relay windings, wires 257 and 216, contact 361, contact at rest and springs 281 and 282, spring 292 and 294 and contact at rest, wires 218 and 219, left windings of the RC translator coil, wires 224 and 226, springs 284-and 271 and their contacts at rest, upper windings of relay 220 and relay 230. Relay 230 does not attract in this @ ir- cuit because the current flows in the unfavorable direction and the upper and lower windings currently have opposite effects.

   The relay 220 however draws in this circuit to open at one point the circuit of the relay 270 at the contact 221 before the relay delayed in operation can draw its armature fully, at the contact 222 it prepares its blocking circuit. through its lower winding.



   In the incoming selector SEL2 the release relay corresponding to the relay 1120 of fig, 12 attracts as a result of the attraction of the line relay and the incoming selector is ready to receive the pulses. When the second train is transmitted by the transmitter, the relays 360 and 370 release each pulse once. At contacts 362 and 372 the relays and 370 momentarily open the circuit of the relay delayed on release, but this relay is kept attracted during the. pulse period as a result of its characteristic.



  At contact 363, relay 360 immediately closes the circuit of the lower coil of relay 220 while sending the pulses to keep relay 220 engaged. At contact 361, relay 330 repeats the pulses to the incoming selector line relay, therefore this line relay releases once for each pulse received. In the incoming selector and under the action of the line relay. The electromagnet

  <Desc / Clms Page number 59>

 works step by step and raises the brushes of the incoming selector to the level corresponding to the first digit after which the selector relay corresponding to relay 1130 in fig. 12 releases and establishes the own control circuit of the rotation electromagnet.

   The rotation electromagnet therefore rotates the brushes 461 to 463 inclusive, of the selector entering the selected level until the test brush 462 has found a free connector, this one is charac- terized by a negative connected to the corresponding bank contact in the selector banks. When the test brush 462 finds the characteristic polarity the selector's polarized switching relay performs the switching in a known manner.



   If we now assume that the connector shown in fig. 5 is the first free connector accessible to the selector in the level the selector switching relay pulls in the circuit comprising: positive taken through its excitation winding, the brush 462, the bank contact 465, the springs of vertical shaft 471 and the contact working, the vertical shaft springs 472, the winding of the relay 410, the negative. When relay 410 attracts, at contact 447 it prepares its own blocking circuit at one point, at contact 448 it prepares the pulse circuit of the ascending electromagnet at one point, at contact 449 it prepares at one point the calling circuit.

   Line relay 403 draws in the following circuit: and negative through the lower and upper windings of line relay 403, normally closed contacts controlled by springs 418 and 417, normally closed contact and spring 415 and 413, contacts 467 and 464 selector debank, brushes 463 and 461, selector circuit, wires 257 and 216 and the bridge closing circuit described previously and comprising the upper windings of the

  <Desc / Clms Page number 60>

 relay 220 and 230 and contact 361. At contact 420, the line relay establishes the power supply circuit for relay 404 delayed on release by means of spring 414 and (its contact at rest.

   Release relay 404, when pulling to contact 421 grounds bank contact 403 through vertical shaft springs 471 to give an additional positive to mark that known selector being busy, the other earth being given by the junction circuit and by the intermediary of the contact 252 put to the. ground, wire 235, contact 392, wire 215, selector switch relay closed contacts and selector brush 462. At contact 422, relay 404 establishes the blocking circuit of relay 410 by means of the normally closed springs controlled by contact 429, of contact 436, of the lower winding of relay 409, of spring 447 and its contact on job.

   Relay 409 does not attract in this circuit because earth is connected to the two pins of the lower coil. At contact 423, relay 404 prepares the pulse circuit at one point, at contact 424 it opens at one point the circuit going towards the release electromagnet RL1 of the connector and the release electromagnet. ration of the call switch.



   Relay 360 at contact 361 repeats the next series of pulses which causes line relay 403 to be released once for each pulse received. Each time the line relay 403 releases, the contact 420 establishes the circuit of the connector electromagnet and the relay-series 406 as follows: positive, spring 420 and its contact at rest, contact 423, contact 428, contact 457, at this point the circuit divides, one branch goes to negative through the winding of the relay 406, the other branch comprises the spring 446 and its contact at rest, the contact 448 and its

  <Desc / Clms Page number 61>

 contact on, the winding of the connector's ascension electromagnet, the negative.

   The relay 406 being delayed on release remains attracted during the sending of the pulses, on contact 429 it opens the blocking circuit of the relay 410 described previously and substitutes for it a new blocking circuit by means of the spring 445 and of its contact at rest to keep relay 410 attracted. Contact 429 opens the circuit of relay 409. At contact 430, relay 406 prepares the circuit of occupancy relay 405 at one point and at contact 431 opens the call circuit at one point. The electromagnet works to bring the brushes of the connector to the level corresponding to the number emitted. At the first step of ascent of the connector brushes the vertical shaft springs 470, 471 and 472 are actuated.

   The vertical shaft springs 471 open the primitive supply circuit of relay 410 and removes one of the earth connections bypassing the lower winding of relay 409. At the vertical shaft springs 472 and theirs. contacts at work the relay 401 circuit is prepared and at the vertical shaft springs 470 the connector release solenoid RL1 circuit is also prepared.



   Shortly after sending this pulse train, relay 406 releases, at contact 429 it connects the lower winding of relay 409 in series with relay 410, which causes the attraction of relay 409 while relay 410 remains attracted.



  The circuit is as follows: positive, contact 422, normally closed contacts controlled by spring 429, contact 436, coil of relay 409, spring 447 and its contact on, coil of relay 410, negative. At contact 445, relay 409 prepares at one point its own blocking circuit through its upper winding, at contact 446 it connects the connector rotation electromagnet to the pulse circuit at the same

  <Desc / Clms Page number 62>

 time that it disconnects the ascension electromagnet.



   Under the action of the following train of pulses, relay 380 repeats again the pulses towards relay 403 which causes relay 406 to attract and now operates the rotation electromagnet as follows: positive, spring 420 and its contact at rest, contacts 423, 428, 457, spring 446 and its contact at work, the connector rotation electromagnet. When relay 406 releases, at contact 429 it closes its blocking circuit passing through the upper winding of relay 409 and opens the circuit passing through the lower winding of relay 409 and the blocking circuit of relay 410 to cause the release of it.

   When relay 410 releases, at contact 447 it prepares a new power supply circuit for itself, at contact 448 it prepares at one point the circuit for sending pulses to the control solenoid SI. the bell switch. The connector rotation electromagnet attracts once for each pulse received to bring the connector brushes to the contacts of the called line. When the relay 406 releases after sending the impulses it opens the blocking circuit of the relay 409 at contact 429, the result is that the latter now releases, at contact 446 it prepares the electronic circuit at another point. - ringing switch control magnet.



   In a manner identical to that which has been described above, the line relay 4u3 of the connector attracts under the action of the ringing digit transmitted to move the brushes 481 and 482 of the ringing switch. This control circuit is as follows: positive, spring 420 and contact at rest, contacts 423, 428, 457, springs 446 and 448 and their contacts at rest, winding of the control electromagnet SM of the bell switch, negative , when the broom 482 of the bell switch engages on the first contact

  <Desc / Clms Page number 63>

 from the bank the circuit of the busy test relay 405 is prepared.



   If the called line is busy, the connector test brush 492 engages on a pin of the grounded bench, it follows that the busy relay 405 attracts at the first time in the following circuit: taken at the pin of the grounding connector bank, brush 492, upper winding of the switching relay 412, contacts of the multiple bank on which the brush 482 is engaged, contact on and spring 430 in series with relay 406, resistance R and winding of occupancy relay 405, negative.

   As a result of the presence of resistance in this circuit, the occupancy relay 405 only partially attracts, it only closes its contact 427 to prepare the circuit which will make it fully draw when the relay 406 delayed in operation releases a little. after the end of sending pulses. Relay 412 is a marginal relay, it does not draw in series with relay 405 and resistor R. When relay 406 releases after sending the impulses it opens at contact 430 the primary supply circuit of the relay. 405 and substitutes a new circuit comprising the normally closed contacts controlled by, the spring 426 as well as the closed contact 427, which causes the closing of the other contacts of the relay 405.



  When relay 405 draws in the second time, at contact 425 it connects the busy tone, taken from the LV wire, to the upper conversation wire to transmit the busy tone to the operator through the conversation wires, at contact 426 it completes its own blocking circuit at earthed contact 422, finally at contact 428 it opens the pulse sending circuit at one point.



   Now returning to the operation of the transmitter and considering when the last digit is finally the /

  <Desc / Clms Page number 64>

 transmitted it can be seen that the finder circuit relay 710 operates in the manner previously described to prepare the talk circuit and to place the upper coil of the relay 730 across wires 791 and 792.

   As no reversal of the polarities has been carried out on the junction wires 308 and 309, the current which traverses the upper excitation winding of the relay 730 flows in the desired direction to cause this relay to be attracted, the result of which is that it at the contact 731 prepares the ignition circuit of the call supervision lamp CS which is however only established when the conversation key K2 of the searcher circuit is returned to the normal position. When the attendant hears the busy tone, she informs the subscriber of set A1 and asks him to hang up the receiver and tells him that she will establish the call later.



   The attendant then reimburses the change that has been deposited by activating the CRA reimbursement key to close contacts 1051, 1032 and 1033. At springs 1031 the circuit of relay 910 of the operator position closes in series with the switch. calling line relay 1330, as follows: positive to spring 1051, wire 1019, relay coil 910, wire 752, key springs 742, wire 686, contact 624, brush 605, bank contact 1305, wire 1345 , upper winding of relay 1330 ,, negative.

   At springs 1033 the positive is connected to wire 1015 to attract relay 970, at contacts 1032 the negative polarity of 110 volts is connected to wire 1017. Response relay 910, when pulling, to contact 911 connects the 110 volt negative to wire 1018 and when relay 970 draws to contacts 971 and 972 it connects the 110 volt negative to the finder brushes through wires 632 and 634.



   When relay 1330 attracts, at rest contacts of

  <Desc / Clms Page number 65>

 springs 1331 and 1332 it disconnects the line relay 1310 from the calling line, to the working contacts it short-circuits the capacitors to allow the passage of the current at 110 volts through the searchers brushes, the wires 1341 and 1342 and the windings of the polarized electromagnet 1308 for collecting. At contact 1333, relay 1550 keeps cut-off relay 1320 attracted. The connection of the current at 110 volts to the relay 1308 causes the operation of this relay which draws its armature in the desired direction to reimburse the deposited parts, after which the springs 1309 return to the normal open position.

   When the line relay 1310 releases, to the spring 1313 and its contact at rest it connects the grounded contact 1324 to the junction release wire 1287 to keep this line occupied, at the contact 1314 it places the wire 1343 to the ground for Prepare the seeker circuit AS response supervision lamp circuit. When the attendant returns the reimbursement key to the normal position, relays 910, 970 and 1330 release.



   - Now returning to the operation of the connector shown in fig. 5 and assuming that the called line is free instead of being busy, we can see that the busy relay 405 does not attract and that when the relay 406 releases after sending the pulses, the relay 412 attracts in the following circuit: positive, contact 422, normally closed contact and spring 427, normally closed contacts controlled by spring 450, bell switch brush 482, relay top winding 412, test brush 492, bank contact 495, wire 498, winding of relay 25, winding of control solenoid 27, negative. Relay 412 attracts and closes contact 456, relay 25 attracts and disconnects line relay 26 and puts the called party's line to earth.

   Relay 412 first closes its contact 456 to establish its control circuit.

  <Desc / Clms Page number 66>

 blocking through its lower winding and earth at contact 422 and to cause the closing of the other contacts.



   When relay 412 draws fully, at contacts 451 and 456 it prepares at various points the conversation circuits and sending inrush current, at contact 452 it establishes the circuit of relay 401, at contact 454 it closes a new one. relay 410 power supply circuit, at contact 455 it earths brush 492 and wire 498 to occupy the line called for the other connectors which have access to it, at contact 457 it opens at one point the local pulse circuit.



   Relay 401 draws in the following circuit: positive to grounded junction release wire 215, passing through the incoming selector and terminating at brush 462, bank contact 465, shaft spring 971 and its contact at work, contact 452, winding of relay 401, negative. At contacts 413 and 415, relay 401 short-circuits the conversation capacitors and disconnects the windings of relays 402 and 403 from the connector's conversation wires, at springs 414 and its contact at rest it opens the circuit of relay 404 at one point, on contact to work it establishes the circuit of the relay 402 through its lower winding in series with the relay 404 which remains attracted.



   The supply circuit of relay 410 is as follows: positive at contact 454, contact 455, normally closed contacts controlled by spring 447, winding of relay 410, negative, When relay 410 attracts to contact 447 it is blocked through the lower winding of relay 409, at contact 449 it prepares the call circuit at one point. Relay 409 draws in series with relay 410. Relay 409 at contact 444 establishes the @B relay callback circuit. When the relay 402 attracts to the contact 419 it opens at one point the circuit of the RLI release electromagnet.

  <Desc / Clms Page number 67>

 connector and the RL4 release solenoid of the bell switch.



   Relay 408 attracts only if the inrush current send number is an odd number, i.e. if we assume that this number is 1, brush 481 establishes the following circuit to attract the relay 408: generator Gl, first contact of the bank and brush 481, multiple contacts and contact 431, contacts normally closed and controlled by spring 441, lower winding of relay 408, negative.



  At contacts 439 and 442, relay 408 reverses the ringing wires, at contact 440 it is blocked through its upper winding than contact 422 earthed, at contact 441 it opens its original supply circuit and completes the circuit. ringtone. The ringing circuit in the present case is as follows: Gl, first contact of the bank, brush 481, multiple contacts, contact 431, contact at work and spring 441, contact 449, contact at work and contact 439, contact at rest and contact 432, conversation wire, ringing of the called station, spring 438 and contact at rest, spring 442 and contact at work, upper winding of the inrush cut-off relay 407, negative.



   If the inrush current sending number is an even number, relay 408 does not attract and the inrush current sending circuit is as follows: from generator and brush'481, multiple bank contacts, contact 449, contact at rest and spring 442, contact at rest and spring 438, contact 458, brush 493, wire 499, subscriber's line and ringing of his set, wire 497, brush 491, contact 451, spring 432 and its contact at rest, winding. upper relay 407, negative.



   When the called subscriber answers the relay 407 draws in the circuit described for sending the inrush current, it closes its contact 437 which establishes its blocking circuit through

  <Desc / Clms Page number 68>

 its lower winding and pulls it fully in to close its other contacts. This circuit is as follows: positive, contact 422, spring 456 and both contacts closed, lower winding of relay 407, negative. At springs 432 and 438 and their contacts at rest, relay 407 disconnects the inrush circuit from the inrush current, at the contacts at work it establishes the conversation circuit.

   At contact 434, relay 407 connects contact 453 earthed to the earth wire through contact 416, at contact 435 it opens the primary supply circuit of relay 410, at contact: 56 it opens the circuit of relays 409 and 410 which release.



   Returning now to the junction circuit of figs, 3 relays of and 4 at the moment when the relay 401 disconnects the / line 405 from the bridge placed on the wires 257 and 216, we can see that the circuit of the relay 220 is open and that this one releases. At contact 221, relay 220 closes the circuit of relay 270 as follows: positive, wire 234, spring 288 and its contact at rest, contact 251, spring 231 and its contact at rest, contact 221, spring 262 and its contact at rest. rest, normally closed contacts controlled by spring 275, winding of relay 270, negative.

   At contact 271, relay 270 opens the circuit of the upper windings of relays 220 and 230, to contacts 271 and 273 it connects the upper and lower windings of line relay 310 to the terminals of wires 257 and 216, i.e. to the terminals of the wires of the line called, at contact 273 it disconnects the negative connected to the left side of relay 370, at contact 274 it prepares the circuit of relay 290 at one point, at contact 275 it completes its blocking circuit at contact 252 earthed . The line relay is now connected to the terminals of the line wires of the called subscriber, when the latter answers the relay 310 attracts.



  * @

  <Desc / Clms Page number 69>

 At contact 311, relay 310 establishes the circuit of relay 350.



  When the relay 350 attracts, at the contacts 351 and 352 it reverses the direction of the current in the junction wires 308 and 309 which causes the release of the relay 730 of the circuit of the finder, this relay when it releases opens the circuit prepared previously for the call supervision lamp CS.



   The operator can proceed to the cashing of the change now or at the end of the communication. To collect the cash, the operator activates the CCA key which closes the contacts 1021, 1022 and 1023. The springs 1021 put the wire 1019 to the ground to attract the relays 910 and 1330 in the circuit described above. At contacts 1023 wire 1015 is grounded to attract relay 970, at contacts 1022 the positive polarity of 110 volts is connected to wire 1018. When relay 910 attracts, at contact 911 it connects current to 110 volts from wire 1017 to wire 1018 so that when relay 970 pulls to close its contacts 971 and 972 the current at 110 volts is connected to the two searcher brushes.

   As previously described, relay 1330 to contacts 1331 and 1332 short-circuits the capacitors and opens the circuit of line relay 1310, at contact 1333 it keeps relay 1320 attracted. At the springs 1331 and 1552 and their contacts at work, the current at 110 volts is connected to the circuit of the station to attract the polarized electromagnet 1308 and cause this collection. when the operator
CCA returns the key / to the normal position relays 1330., 910 and 970 release as before.



   After the called party answers the operator returns the K2 conversation key of the searcher circuit to the normal position to connect the calling and called subscribers in the following conversation circuit: sender and receiver of the set

  <Desc / Clms Page number 70>

 Al, conversation wires, capacitors, wires 1541 and 1342, brushes 601 and 602, contacts 611 and 612, normally closed contacts controlled by the springs 652 and 654 of the connection relay released, this relay releases when the attendant gives the key K2 in rest position, wires 681 and 682, windings of the RC translator coil, wires 791 and 792, brushes 1171 and 1172, wires 581 and 582, wires of junction 508 and 309, spring 501 and 302 and their contacts at rest, RC translator coil, wires 218 and 219,

   contacts at rest and springs 292 and 294, contacts and springs 281 and 282, wire 217, contact 361, wires 257 and 216, brushes 461 and 463, springs 413 and 415 and their contacts at work, contacts at work and springs 432 and 438 , contacts 451 and 458, brushes 491 and 495, wires 497 and 499, wires 11 and 12, called station circuit. The supply current is given to the caller through the windings of line relay 1310, the supply current is given to the called party through the windings of line relay 310. uand the called subscriber hangs up its receiver, line relay 310 releases and at contact 311 opens the circuit of relay 350 which consequently releases.

   When the relay 350 releases, at the contacts 351 and 552 it reverses the direction of the current in the junction wires 308 and 309 which causes the attraction of the relay 730 of the searcher circuit. When relay 730 attracts, on contact 731 it closes the ignition circuit of the call supervision lamp CS, which indicates to the operator that the called party has hung up his receiver.



   When the subscriber calling from set Al hangs up his receiver, line relay 1310 releases, at contact 1314 he places wire 1343 to earth to switch on the AS supervision lamp, as follows: positive, contact 1314, wire 1434, contact 1303 of the researcher bench, brush 603, wire 683, springs 741 of the key and their contacts at rest, supervision lamp

  <Desc / Clms Page number 71>

 AS, negative. By switching on the AS lamp, the attendant is informed that the caller has hung up his receiver. The operator can now actuate the key K2 to cause the pulling of the connection relay 650. After having actuated the key K2 the operator actuates the release key RLC to put the wires 637 and 1016 to the ground at the springs. 1071 and 1072 of the key.

   Relay 930 remains attracted due to grounding of wire 637, at the same time the upper blocking winding of relay 710 is short-circuited by the positive of communication release wire 637, contact 656 , wire 685, contact 713, the top winding of relay 710, the positive. Relay 710 therefore releases, at contact 711 it opens the circuit of relay 730 and of the junction line relays 360 and 370. At contact 712, relay 710 opens the conversation circuit at one point, at contact 713 it opens at another point its own blocking circuit at contact 715 it disconnects the positive of the junction release wire 793, at contact 716 it disconnects a connections to the earth of the occupancy lamp BL.

   When the relay 730 releases, at contact 731 it opens at one point the circuit described above for supplying the supervison lamp CS. Disconnecting the positive from junction release wire 793 as a result of releasing relay 710 at contact 715 releases selector relay 1140 and also releases relay 550 of the junction circuit shown in FIG. 6. The selector relay 1140, on releasing, releases the selector in the manner which has already been described.

   When relay 550 releases, at contact 551 it reconnects the upper winding of AC relay 530, at contact 552 it disconnects the earth of the bias winding of relay 560 and wire 573, in this way the circuit joint shown in FIG. 6 has now returned to normal condition.

  <Desc / Clms Page number 72>

 



   When line relays 360 and 370 release at contact 361 they open the contact conversation circuit at one point they remove one of the earth connections of relay 250, at contact 372 they disconnect the remaining earth of relay 250 to release. this one. When relay 250 releases at contact 252 it disconnects the earth of wire 235 and wire 215 to release the input selector and to release relay 401. At contact 252, relay 250 opens the blocking circuit of relay 270 and disconnects the earth from the winding of relay 230.

   At contact 254, relay 250 disconnects ground from junction release wire 247 and reconnects the negative of transfer relay coil 280 to it to mark this junction circuit free in the selector banks. When 1c relay 270 releases, at contacts 271 and 272 it disconnects line relay 310, at contact 271 it reconnects the upper windings of relays 220 and 230 to wires 218 and 219. when the earth is disconnected from the release wire of junction 215 following the release of relay 250, relay 401 releases and at contact 414 opens the circuit of relays 402 and 404. When relay 402 releases, at contact 419 it prepares at one point the circuit of release electromagnets 1L1 and 1L4 of the connector and the ringer selector.

   When the relay 404 releases, at contact 422 it disconnects the earth of the ground wire to release relay 12 and relay 407 as well as relays 409, 410, 408 and 405 if they have attracted. At contact 424 the relay 404 completes the circuit of the release solenoid RL1 of the connector and of the release solenoid RL4 of the ring selector at the contact 419 grounded and through the springs of the ring selector. tree of the respective switch sets. By moth of the operation of the switch release solenoid

  <Desc / Clms Page number 73>

 strike the brushes 481 and 482 are returned to the normal position, thereby the shaft springs 480 open the circuit of the release solenoid of the bell switch.

   As a result of the operation of the connector release electromagnet, the brushes thereof are returned to the rest position in the well known manner and the vertical shaft springs 470 of the connector open the circuit of the electromagnet. release thereof, to vertical shaft springs 471 and 472 the negative taken through the coil of relay 410 is connected to contact 465 of the selector bank to mark this wire as free in the banks of the switches. incoming selectors. When relay 412 releases, on contact
455 it disconnects the positive of wire 498 to release relay 25 of preselector C and when this relay is released all the equipment put into service to establish communication to the called station has returned to its normal position and is ready to sell other calls.



   In order to release the connection established to the calling station, the operator actuates the RLA release key, thereby grounding the wires 1015 and 639 by means of the springs 1042 and 1041. The connection of ground to wire 1015 causes relay 970 to operate and connection to ground of wire 639 short-circuits relay 640, so the latter releases in the manner previously described. When the relay 640 releases, to the spring 643 and. when the contact is on, it disconnects the earth of the researcher's brush 604 to release the relays 610 and 1320.

   At the spring 643 and its contact at rest, the relay 640 causes the searcher release electromagnet RL2 to be drawn in to release the searcher brushes as described previously, at contact 661 it turns off the occupancy lamp BL. When relay 1320 releases, at contact 1321 it reconnects the en-

  <Desc / Clms Page number 74>

 upper bearing of line relay 1310 to the lower conversation wire of line Al through contact 1332 ,, to contact 1324 it connects the lower winding of relay 1330 to the junction release wire 1287 to mark this line as free for connectors that have access to it.



  All devices that have been put into service to establish communication have returned to idle and can be used for further calls.



   One of the new features of the line circuits shown in fig, 14 is that in the event that the operator forgets to reimburse or to collect the change deposited at the end of the corallunication, the circuits are designed to cause a false call which alerts the operator, when she wants to answer and she gets no answer she has been instructed to cash the change.

   For this purpose, it will be assumed that the operator forgot to cash the change at station A1. Therefore, when the communication is finished, line relay 1310 remains drawn into the following circuit: positive, windings of the electro- polarized magnet 1308, change control springs 1309, closed at the moment since the change has not been cashed, lower conversation wire, spring 1332 and its contact at rest, contact 1321, upper coil of the line relay 1310, negative.



  Since the line relay 1310 remained attracted after the subscriber hung up his receiver the release of the relay 1320, when the connection was cut, the starter wire 1316 grounded, which caused the sending of a call to the operator as described previously. When the operator replies she causes a searcher to search for this line, when she receives no response she realizes that an operator forgot to collect the change or refund it, so she activates the key of-

  <Desc / Clms Page number 75>

 CCA checkout to cause the cash to be cashed as described above.



   The operation of the junction circuit of fig. 3 and 4 is somewhat different for an incoming call on wires 308 and 309 when a subscriber other than a subscriber with a prepaid extension makes a call. As described previously, the special connector of fig. 5 was brought into service because the previous call was requested by a prepaid station, but in the case where an ordinary subscriber makes a call a regular connector is put into service through the banks of the incoming selector. The ordinary connector instead of cutting off the power and giving direct switching reverses the direction of the current on wires 357 and 316 in the well known manner.

   This reversal of the current direction causes the junction circuit to operate slightly different in that the relay 230 is now attracting while in the case previously described the circuit of the relays 230 and 220 was cut off.



   At this moment the relays 350, 370, 250 and 220 are pulled and the reversal of the current in the wires 257 and 216 causes the relay 230 to pull up. Since the relay 220 does not release in this kind of communication the relay 270 does not release. do not attract.



  When the relay 230 attracts, the spring 231 and its contact at rest it opens at another point the circuit of the relay 270; on contact on, it establishes the circuit of line relay 310, on contact 232 it also establishes the supply circuit for relay 260. When relay 260 attracts, on contact 262 it opens the relay circuit at another point. 270, at contact 261 it disconnects the negative on the left side of relay 370. The circuit of relay 310 is as follows: positive, wire 234, spring 288 and its contact at rest, contact 251, spring 231 and its contact on, wire 225, top winding

  <Desc / Clms Page number 76>

 ùu line relay 310, negative.

   At contact 311, relay 310 completes the circuit of relay 350 and the latter at contacts 351 and 352 reverses the direction of the current on wires 308 and 509 to cut the circuit of supervision lamp CS as described previously. Because the called subscriber has hung up his receiver, the direction of the current is reversed in the wires 257 and 216 to release the polarized relay 230. When the relay 230 releases, at contact 231 it opens the circuit of the relay 310 and this at contact 311 opens the circuit of relay 550. When relay 350 releases at contacts 351 and 352 it reverses the current in wires 308 and 309 to give the desired signal to the attendant.



  The operator cuts off the communication established in the manner described above.



   Deferred calls.



   ----------------
It will now be assumed that the operator wishes to set up a deferred call from set To set A1 because during a previous call the operator was not able to establish communication to set A1. the operator activates the DLC deferred call key to close the springs 1051 and 1052, The springs 1052 earth the contacts of the first level of the vertical searcher bench through the wires 399 and the springs 1051 put the wire 1024 to earth to attract relay 960 and relay 9 @ 0 through the normally closed contacts controlled: s by spring 955.

   When relay 960 attracts to contact 961 it connects the marking negative to wire 764 to mark this position as establishing a deferred call, in the banks of researchers associated with the circuit of the researcher, At contacts 962 and 933, relay 960 prepares at certain points the pulse circuit coming. transmitter, on contact 964 it puts wire 966 to earth to start the search.

  <Desc / Clms Page number 77>

 cheur the transmitter circuit to find this position, marked by wire 764; at contact 965 it attracts relay 970, at contact 966 it grounds starter wire 638 with the aim of attracting starter relay 640 from the searcher circuit when the conversation key K2 is actuated.

   The transmitter circuit finder therefore works, it searches for the marked contact in the bank, that is to say the contact to which the wire 764 ends. When the transmitter circuit finder finds the marked contact in the bank the transmitter circuit performs the switching and associates the transmitter with this position. Relay 920 draws in series with relay 960, at contact 921 it prepares another circuit to subsequently start the searcher of the transmitter circuit and to associate the transmitter with the part of the searcher circuit comprising the selector, at contact 922 it opens the circuit of relay 940 at one point to prevent the operation of this relay when the key K2 is actuated.



  When the relay 970 attracts to the contacts 9'71 and 972 it prepares at other points the circuit of pulses coming from the circuit of the transmitter.



   The operator then activates the conversation key K2 of a free seeker circuit to attract the connection relay of this circuit and to associate her position with it. If we assume that the key K2 of the finder circuit of fig. 7 and 8 has been activated, it is the connection relay 650 which attracts under the action of its upper winding via the test lead 753 grounded and the springs 744 of the key.

   When the connection relay 650 attracts to its upper contacts it associates circuit 4 with the operator position, with contact 657 it locks itself by means of its lower winding in series with relay 850, with contact 658 it blocks itself. connect wire 638

  <Desc / Clms Page number 78>

 earthed to the top winding of relay 640 to cause it to pull.

   When relay 640 attracts it causes the operation of the retort seeker described previously but in this case as the first level of the vertical test bench has been marked as calling through the 699 grounded wire the brushes of the emitter step vertically, relay 620 circuit is as follows: wire 699 grounded, first level contact of vertical bench, vertical brush 607, contact 622, lower relay 620 winding, spring 631 and its contact at work, spring 623 and its contact at rest, winding of the ascent electromagnet, negative.

   In a manner identical to that which has already been described, the operation of relay 620 causes the searcher brushes to rotate in the first level until an LED circuit reserved for deferred calls is found free, at this moment. switch relay 610 pulls to connect the finder circuit to the selected LED circuit.

   Assuming that the LED circuit shown in the lower part of FIG. 6 is the first that was found free in the first level, the circuit of the switch relay 610 of the finder circuit is as follows: positive at contact 643, upper excitation winding of relay 610, test brush 604, contact of Bank 504, Relay 579 winding, negative, Relay 579 draws in series with relay 610 and the latter connects the call to this special circuit to the delayed calls.

   When the relay 579 attracts to the contact 597 it connects the windings of the line relay of the selector SEL3 shown in the lower part of the pin 6 to the terminals of the wires 761 and 762 of the emitter, to the contact 598 it prepares the circuit of blocking of relay 578 and the bias circuit of the lower winding of relay 577, at contact 599 it prepares at a point

  <Desc / Clms Page number 79>

 the circuit of relay 578, at contact 500 it earths the junction release wire of selector SEL3 to attract the series relay thereof and to prepare the selector for operation.



   The attendant then activates the transmitter's digit keys in accordance with the digits of the requested number, she then actuates the start-up key so that the transmitter transmits the digits corresponding to station A. The circuit for sending pulses by the emitter is as follows: emitter pulse springs, wires 761 and 762, contacts 963 and 962, NO contacts and contacts 972 and 971, wires 632 and 634, contacts 651 and 653, contacts 611 and 612, brushes 601 and 602 of the finder, contacts at rest 501 and 502, contact 597, normally closed contacts controlled by springs 587 and 585, upper and lower windings of the selector line relay (not shown), negative and positive.

   The selector line relay draws into this circuit and releases with each transmitted pulse to cause the selection of a free trunk circuit which leads to the remote automatic office. If we assume that the junction circuit of Figs. 3 and 4 is the junction circuit selected by the selector of FIG. 6 we see that when this selector performs the switching the line relays 360 and 370 of the junctions attract in the circuit of pulses coming from the transmitter and ending at the selector through the junction wires 308 and 309.

   Under the action of the remaining pulses transmitted by the transmitter, the line relay 360 from the junction to the contact 361 repeats pulses towards the incoming selector and the connector relay shown in fig. 5 to pull / of the trunk circuit, the incoming selector and the connector, in a manner identical to that previously described for an incoming call intended for station A.

  <Desc / Clms Page number 80>

 



   After the transmitter transmits the entire series of pulses from station number A the wire 763 is grounded in the transmitter to cause the pull of relay 950.



  When relay 930 attracts to contact 951 it closes a bridge, including the DC shock coil, placed at the terminals of wires 332 and 6 @ 4 to keep junction circuit relays 330 and 370 attracted, at contact 952 it completes the circuit of relay 578 of the delayed call junction circuit, at contact 953 it opens the circuit of relay 960 and also closes its blocking circuit to wire 1024 earthed.



  When relay 960 releases, at contact 961 it disconnects the marking polarity of the transmitter's researcher banks, at contacts 962 and 963 it opens the transmitter pulse circuit at certain points, at contact 964 it removes a connections to the earth of wire 696, the latter however remains connected to earth at contact 853 by relay 850 which is attracted. At contact 963, relay 960 opens the circuit of relay 970 to cause the release of the latter and at contact 966 it disconnects the earth of the starter wire 638.



  Relay 920 does not release when the relay 960 circuit opens because it remains attracted by the action of its lower winding in series with the lower winding of start relay 640 of the seeker circuit.



   The circuit of relay 578 is as follows: positive, contact 952 of relay 950, wire 751, contact on and spring 741 of the key, wire 683, brush 603, bank contact 503, contact 599, contacts normally closed controlled by springs 595, winding of relay 578, negative, When relay 578 attracts to contacts 592, 593 and 594 it connects the RC translating coil, to spring 594 and to its working contact it places the upper winding excitation of the relay 577 to the terminals of the junction wires 308 and 309 for main-

  <Desc / Clms Page number 81>

 keep line relays 360 and 370 drawn.

     At contact 595, relay 578 closes its blocking circuit and establishes the circuit of the lower bias winding of relay 577, at contact 596 it prepares the supervisory circuit at one point.



  Relay 577 attracts since the direction of current flowing through wires 308 and 309 of the junction in the direction intended to support the action of the bias winding. At contact 590, relay 577 connects a resistor in series with its polarization winding, at contact 591 it grounds the finder brush 603 through contacts 596 and 599 to prepare the lamp circuit. of supervision AS.



   When communication has been established to set A and the subscriber has answered line relay 310 of fig. 4 draws the relay described previously into the circuit of the subscriber's loop in the manner. At contacts 311 310 establishes the circuit of relay 350, this at contacts 351 and 352 reverses the current in the line wires of junction 308 and 309 to cause the release of relay 577 of the delayed call junction circuit. When relay 577 releases, at contact 591 it disconnects the earth of the search engine brush 603 to open the circuit prepared for the AS supervision lamp.



   The operator puts the DLC key for deferred calls back in the rest position, so the springs 1052 remove the positive from wire 699 to remove the earth from the contact of the first level of the vertical bench, the springs 1051 cause the release of relay 950. When the relay 950 releases at contact 951 it opens the bridge which was described previously for the blocking of the junction line relays 360 and 370 but these relays remain attracted under the action of the excitation winding of the relay 577, at the contact 952 it disconnects the earth of the wire 751 by which the relay 578 attracted at the beginning

  <Desc / Clms Page number 82>

 
When relay 960 has released and removed from contact 964 the marking polarity of wire 764,

   the seeker circuit finder was released and as the finder circuit relay 650 connected a tag polarity across wire 774 to the transmitter seeker bench, the transmitter finder is working again to find and connect the transmitter circuit to the researcher circuit in the manner described above, The attendant can now activate the digit keys corresponding to the digits of the telephone number of the A1 set, after which she activates the corresponding start key.



  The transmitter transmits pulses through wires 772 and 771 to operate the selector of Fig. 12 in the manner previously described. In the present case, the first digit transmitted by the transmitter causes the operation of the selector which selects a free control circuit towards a prepayment station, one of them is shown in fig, 13.



   If we assume that the control circuit of a prepayment station of FIG. 13 is the circuit entered by the selector, the relay Il ': 1: 0 draws in series with the buzzer relay of the connector CON in fig. 13, this relay corresponds to relay 410 of the connector shown in FIG. 5. The attraction circuit of relay 114C is as follows; positive, contact 1122, brush winding 1173, Upper relay excitation slowdown 1140, contact 1121, / bank contact 1183, wire 1193, wire 1207, vertical shaft springs and connector bell relay winding, negative.



  Relays 1230 and 1240 now attract in the sending circuit: pulses coming from the transmitter, as follows: emitter pulse springs, wires 771 and 772, wires 791 and 792, springs 1141 and 1142 and their working contacts, brushes 1171 and 1172, wires 1191 and 1102., left windings of the RC translator coil, upper and lower windings of the differential relay 210, normally closed contacts controlled by the springs 1221 and 1222, windings of the relays 1240 and 1230, positive and negative, respectively, When relay 1230 attracts, at contact 1231

  <Desc / Clms Page number 83>

 it opens the circuit of reimbursement relay 1296 at one point,

   at contact 1232 it causes relay 1250 to attract. When relay 1240 attracts, at contact 1243 it establishes the same circuit of relay 1250, at contact 1241 it places the upper winding of relay 1290 to the terminals of the conversation wires 1205 and 1; 06 to attract the line relay from the connector. When relay 1250 attracts, at contact 1251 it puts the junction release wire 1193 to earth to keep relay 1140 attracted in the selector, at contact 1152 it prepares the circuit of relay 1280 at one point.

   The line relay of the connector and the relay 1290 of the control circuit of the prepaid station draws in the following circuit: positive and negative through the windings of the line relay in the connector, contacts controlled by the relays corresponding to relays 02 and 401 of FIG. 5, wires 1206 and 1205, contact 1241, springs 1202 and 1201 and their contacts at rest, straight windings of the RC translating coil, spring 1261 and its contact at rest, upper winding of relay 1290. At contact 1291, relay 1290 prepares its own blocking circuit while the pulses are being sent, at contact 1292 it closes the circuit of relay 1280 through contact 1252 which is earthed.

   When relay 1280 attracts, at contact 1281 it prepares at another point the circuit which keeps relay 1290 attracted while sending pulses, at contact 1282 it prepares the circuit of relay 1260 at one point and at contact 1283 it completes its blocking circuit via the 1252 earthed contact. In the connector the operation of the bell relay corresponding to the relay 410 and the line relay prepare the connector so that it operates in a manner identical to that described for fig. 5.



   Under the action of the next series of pulses from the transmitter, line relays 1230 and 1240 release once on each pulse. At contacts 1232 and 1243 the circuit of the delayed release relay 1250 is momentarily interrupted but this relay remains attracted during the sending of the pulses due to its special characteristic. At contact 1242 the shoe shine

  <Desc / Clms Page number 84>

   passing! by the lower winding of relay 1290 closes via contact 1281 to keep this relay attracted, at contact 1241 relay 1240 repeats the pulses to the line relay of connector CON.

   Operation of the connector line relay operates the ascending electromagnet which raises the connector brushes one step vertically with each pulse received. After this series of pulses the connector rotation electromagnet circuit is prepared and under the action of the following train of pulses transmitted by the transmitter the line relay and 1 rotation electromagnet will cause the rotation. brushes of the connector which will engage on the pins of the called line.

   Under the action of the last digit or ringing digit transmitted by the transmitter, relay 1240 to contact 1241 repeats the pulses again to operate the line relay of the connector and for the selector control electromagnet bell operates its brushes to select the appropriate inrush current generator in a manner identical to that described for the connector at pin 5.



   Under the action of this last digit the connector's switching relay attracts, if the line is free, the connector switches and disconnects the line relay from the wires 1205 and 1206 of the connector, which causes the release of relay 1290 after sending the pulses.



  When relay 1290 releases, spring 1292 and its contact at rest completes the circuit of relay 1260, as follows: positive, contact 1252, spring 1292 and its contact at rest, contact 1282, winding of relay 1260, negative. When relay 1260 attracts, to spring 1261 and its contact at rest it opens at another point the circuit of the upper winding of relay 1290, to the working contacts of springs 1251 and 1262 it connects the upper and lower windings of the relay 1270 at the terminals of the conversation wires of the called line '. On contact 1263, relay 1260 removes a partial branch circuit placed at the terminals of the relay winding

  <Desc / Clms Page number 85>

   1230, at contact 1264 it establishes its own blocking circuit through contact 1252 earthed.

   



   When the transmitter has finished transmitting the last digit, a positive is connected to wire 773 to attract relay 710, as previously described. When relay 710 attracts, at contacts 711 and 712 it inserts the translating coil and completes the conversation circuit. It connects the upper winding of relay 730 to the terminals of wires 791 and 792 to cause this relay to pull under the action of the positive and negative taken through the windings of relays I230 and 1240. On contact 731 relay 730 prepares the supply circuit of the supervision lamp CS at one point.



   When the called subscriber answers, he causes the relay of the connector corresponding to the relay 407 of FIG. 5, the called line is connected to the terminals of the windings of relay 1270 to cause the attraction of the latter.



  This circuit is as follows: negative and positive taken through the windings of relay 1270, springs I26I and 1262 and their working contacts, right winding of the RC transfer coil, rest contacts and springs 1202 and 1201, contact 1241, wires 1206 and I205, closed contacts in the connector, brushes 1276 and 1275, wires 1286 and 1285, station fork springs, microphone and station induction coil called Al.



  On contact 1271, relay 1270 closes the circuit of relay 1220.



  When relay 1220 attracts, at contacts 1221 and 1222, it reverses the direction of the current in wires 1191 and 1192 to cause the release of relay 730 in the finder's circuit, at contact 1223 it prepares its control circuit at one point. clean blocking, at contact 1224 it prepares another blocking circuit for relay 1250, at contact 1225 it prepares the blocking circuit keeping relays 1260 and 1280 attracted.



  The conversation circuit between the set A1 and the operator's position is established through the conversation wires

  <Desc / Clms Page number 86>

 and the translator coil RC of FIG. 13. It also borrows the translating coil RC from fig. 8 and terminates via contacts 652 and 854 at the operator's station.



   The operator can now activate the CCA coin collection key to cash the coins that have been deposited. After the key is operated, the springs 1023 ground wire 1015 to energize relay 970. Springs 1022 connect the positive polarity of IIO volts in the circuit comprising wire 1018, the on contact and the spring. 97I of relay 970 attracted, wire 634, contact 653, contact 612, brush 602, bank contact 502, contact 593, the lower right winding of the RC translator coil of the junction circuit reserved for deferred calls , contact 589, windings of relay 575 and earth.



   Relay 575 draws in this circuit and, at contacts 584 and 585, grounds the two jumper wires 308 and 309 through selector brushes 563 and 564 to cause the pull of differential relay 540 and releasing the line relay 360 from the junction, in a manner identical to that described previously.



  When the differential relay 340 attracts and the line relay 360 of the junction releases to the contacts 363 and 343, it closes the supply circuit of the collection relay COL of fig. 3 through wire 239. At contact 298 the collection relay connects the positive polarity of 110 volts to the working contacts of springs 292 and 294. At contact 296 it completes the supply circuit of relay 290. The circuit of this relay borrows the 234 grounded wire and contacts 274 and 296. At contacts 292 and 294, relay 290 connects the positive of the 110 volt battery to the wires

  <Desc / Clms Page number 87>

 257 and 216 through contact 291.

   At contact 295, relay 290 closes the blocking circuit of relay 350 which is attracted since the circuit of line relay 310 is open to springs 292 and 294 and their contacts at rest.



   Connecting a positive polarity of 110 volts to wires 257 and 216 causes the cash deposited in station A to be cashed in in the well known manner.



   The attendant then returns the conversation key to the rest position to disconnect its position from the finder circuit and to connect the lines of the calling and called subscribers in the following conversation circuit: set A and wires II and 12, wires 497 and 499, brushes 491 and 493 of the connector, contacts 451 and 458, contacts 432 and 438, contacts 413 and 415, brushes 461 and 463, wires 257 and 216, contact 361 and wire 217, contacts at rest and springs 281 and 282, contacts 292 and 294, wires 218 and 219 and transla- trioe RC coil, contacts at rest and springs 301 and 302, junction wires 308 and 309, wires 581 and 582, brushes 563 and 564, normally closed contacts controlled by springs 587 and 585, contact 594, translator coil RG of the junction circuit for deferred calls, contacts 592 and 593,

   contact 597, bank contacts 501 and 502, finder brushes 601 and 602, contacts 6II and 612, normally closed contacts controlled by springs 652 and 654, wires 681 and 682, contact 712 and normally closed contacts controlled by res - output 721, translating coil of the seeker circuit, contact 711 and normally closed contacts controlled by spring 722, wires 791 and 792, springs II4I and II42 and their contacts on, brushes 1171 and II72, wires II9I and II92, RC translator coil of the station control circuit, prepayment, contacts at rest and springs 1201 and 1202, contact 1241, wires 1205 and 1206, closed contacts of the connector and brushes 1275 and 1276, wires 1285 and 1286, circuit of

  <Desc / Clms Page number 88>

 manual prepayment station Al.

   The supply current for station A is supplied through the windings of relay 310 and the supply current for station Al is supplied through the windings of relay 1270.



   If, for some reason, Empress wishes to refund the change instead of cashing it, she can do so by activating the CRA refund key while the seeker's K2 conversation key is still activated. Closing springs 1033 places wire 1015 to ground to pull relay 970. Closing springs 1032 connects negative polarity of 110 volts to the following circuit: wire 1017, spring 972 of relay 970 attracted and its contact to work, wire 632, contact 651, contact 6II, brush 601, bank contact 501, contact 597, contact at work and spring 592, upper right winding of the RC translator coil of the delayed call junction circuit, relay winding rebate 576 and contact 586 grounded.

   Relay 576 draws in this circuit and at contacts 587 and 588 connects negative to two jumper wires 308 and 309 through selector brushes 563 and 564 and wires 581 and 582.



   Connecting a negative to the two wires 308 and 309 causes the pull of the differential relay 340 and the release of the line relay 370 from the junction. At contacts 373 and 342, relays 370 and 540 earth wire 238 to attract the refund relay REF which at contact 297 completes the supply circuit of relay 290 and at contact 299 connects the negative polarity of IIO volts to the working contacts of the springs 292 and 294 of the relay 290 attracted and to the circuit described above, resulting in the polarized collection electro of the station A, to cause when

  <Desc / Clms Page number 89>

   this electromagnet works the reimbursement of the deposited currency.



   If it is now assumed that for some reason the charge for a deferred call has to be paid again, and if the subscriber to station Al agrees to make this payment, the Empress will ask him to deposit the required currency, after which she will activate the Another CCC payment key.

   As a result of the actuation of this key, the springs 1091 put the wire 1025 to the ground to attract the relay 980, the springs 1092 put the wire 63 to the ground to make the relay 720 attract, the springs 1093 put the wire 1026 to ground to prepare a circuit that grounds wire 792 also, springs 1094 ground wire 1028 to prepare the circuit that grounds wire 791, springs 1095 ground wire 1016 to attract relay 990. The supply circuit for relay 720 is as follows: spring 1092 grounded, wire 636, contact 655, wire 684, winding of relay 720, negative. At contacts 721 and 722, relay 720 cuts off the RC translator coil finder circuit and directly connects wires 791 and 792 to wires 681 and 682.

   At contact 723, relay 730 opens at one point the circuit of the bias winding of relay 730. When relay 980 attracts to contact 982, it connects wire 1026, grounded, to wire 1027. When relay 990 attracts, to contacts 991 and 992, it connects the positive of wires 1027 and 1028 to wires 791 and 792 through wires 681 and 682. of contacts 712 and 7II and of the working contacts of springs 721 and 722.

   Wires 791 and 792 are both grounded and this ground extends through brushes 1171 and 1172, wires II9I and 1192, differential relay windings 1210, and line relays 1230 and 1240; Relay

  <Desc / Clms Page number 90>

 differential 1210 is unbalanced in this circuit; it therefore attracts its armature and relay 1240 is short-circuited, which causes it to release. The differential relay 1210 being attracted and the relay I240 being released, the following circuit is established to cause the relay I295 to be attracted; earth, contact 1242, contact 1211, relay winding 1295, negative.



   At contact 1213, relay 1210 closes the blocking circuit of relay 1220 through closed contact 1223.



  Relay I240, at contact I24I momentarily opens the circuit of relay 1270 but this has no effect at the moment since relay 1220 is kept attracted through contact I2I3 earthed. When relay 1295 attracts, at contact 1297, it completes the supply circuit of relay 1200, at contact 1293 it connects the positive polarity of IIO volts to the working contacts of springs I20I and 1202. When relay I200 attracts, on contact 1204 it closes another blocking circuit of relay I220, at contact 1208 it short-circuits the open contacts of spring I24I, at contacts I20I and 1202 it connects the positive polarity of 110 volts to wire 1206.

   This polarity is extended through the closed contacts of the connector, the brushes 1275 and 1276; the wires 1285 and 1286 to the coin-operated station A1 through the springs 1309 and the windings of the collection electromagnet I308 to earth. Applying polarity across the windings of the 1308 cashing relay causes the cash to be cashed in the well-known manner, if, for some reason, the change must be refunded to the subscriber. A1, the appropriate redemption key CRC should be activated. Springs 1081 ground wire 1025 to attract relay 980. Springs 1083 ground wire 636 to attract relay 720.

   Springs 1083 connect negative polarity to wire

  <Desc / Clms Page number 91>

 1028, springs 1084 connect the battery to wire 1026, and springs 1085 ground wire 1016 to attract relay 990. When relay 980 pulls, at contact 982 it connects the negative of wire 1026 to wire 1027.



   When relay 990 pulls, at contacts 991 and 992, it connects the negative polarity of leads 1027 and 1028 to seeker leads 681 and 682 through the circuit that was previously described. Relay 720 draws in this circuit, and at contacts 721 and 722 removes the trans-latrioe RC coil and connects wires 681 and 682 to wires 791 and 792.



   Negative polarity is now connected across wires II9I and 1192, to pull differential relay 1210, to release relay 1230, and to keep relay 1240 pulled. At contacts 1212 and 1231 the supply circuit of the reimbursement relay 1296 closes following the attraction of the differential relay 1210 and the release of the line relay 1230. When the relay 1296 attracts, at contact 1298, it establishes the relay circuit 1200 and to contact 1294 it connects the negative polarity of IIO volts to the working contacts of springs 1201 and 1202 When relay 1200 attracts, to springs I20I and 1202 and their contacts at rest, it disconnects relay 1270, at contact 1204 it establishes the blocking circuit of relay 1220 while relay 1270 remains attracted.

   At contacts I20I and 1202, relay 1200 connects the negative polarity of 110 volts to the talk wire to cause the collecting electromagnet 1508 to be drawn in the desired direction and refund the money which has been deposited. After returning the reimbursement CRC key to the normal position, the attendant puts the K2 key back at rest and thereby completes the conversation circuit between the subscribers in an identical manner to that which was

  <Desc / Clms Page number 92>

 previously described.



   At the end of the conversation and the fact that the subscriber of station A hangs up his receiver, line relay 310 releases, at contact 311 it opens the circuit of relay 350 which, when it releases, at contacts 351 and 352 reverses the direction of the current in the wires 308 and 309 of the junction to cause the attraction of the relay 577 in the junction circuit of the deferred calls. When relay 577 attracts, at contact 591, it powers the AS supervision lamp in the following circuit: earth, contact 591, contacts 596 and 599, bank contact 502, researcher brush 603, wire 683, spring 741 and its contact at rest, filament of the AS supervision lamp, negative. When the subscriber to set Al hangs up his receiver, the relay circuit 1270 opens; this relay releases and on contact 1271 it opens the circuit of relay I220.

   When relay 1220 releases, at contacts 1221 and 1222 it reverses the direction of the current in wires II9I and II92 to attract relay 730 from the finder circuit.



  Relay 730, at contact 731, completes the circuit which was established previously to cause the ignition of the lamp CS in the searcher circuit.



   Due to the fact that the calling and called subscriber supervision lamps have come on, the operator will again actuate the key K2 of her seeker circuit to cause the relay 650 to attract once again as described previously. The operator then activates the RLCA release olef. Springs 1061 ground wire 637 to short the top winding of relay 710 which releases the relay as described previously. Springs 1062 ground wire 639 to short the lower winding of start relay 640 which therefore releases as previously described. When the

  <Desc / Clms Page number 93>

 relay 710 releases, on contact 711 it opens the circuit of relays 1230 and 1240 which causes their release.

   At contacts 1232 and 1243, relays 1230 and 1240 open the circuit of relay 1250 which therefore releases after a short time. At contact 1251, relay 1250 disconnects the earth of wires 1193 and 1207 to release the selector in fig. 12 and the connector of FIG. 13 as described above. On contact 1252, relay 1250 opens the power supply circuit for relays 1280 and 1260 and they release. All the equipment which had been put into service for the establishment of the connection to the station A1 has returned to idle and can be used for carrying out another call.

   When the start relay 640 releases the finder, as described previously, and qutl disconnects the earth of the brush 604 and of the bank contact 504, it causes the release of the relay 579. When the relay 579 releases, at contact 500 it releases the selector associated with the junction circuit for deferred calls, at contact 598 it opens the starting circuit of relay 578 and the latter releases. At contact 594, relay 578 opens the loop placed at the terminals of wires 308 and 309 of the junction to cause the release of line relays 360 and 370 of the junction and to release, in the manner which has been described previously, the devices which have been used to establish the connection to station A.



   Deferred call from A1 to A.



   A brief description of a deferred call from set A1 to set A will be given below: It will therefore be assumed that the operator in order to establish this communication first activates the deferred call DLC key to close the contacts of the I05I and 1052 springs. The 1052 springs

  <Desc / Clms Page number 94>

 ground wire 699 to mark the first level of the finder's vertical bench and the I05I springs establish the power supply circuit for relays 960 and 920 through wire 1024.

   When relay 960 attracts, at contact 961 it marks the transmitter's finder-finder bench, at contact 964 it puts wire 696 to earth to start the transmitter's finder-finder in search of the marked contact in the bench, at contacts 962 and 963 it prepares the pulse circuit coming from the transmitter at one point, at contact 965 it attracts relay 970 and at contact 966 it puts starter wire 638 to earth to attract the relay of start 640 when the key K2 of a free seeker circuit is operated. The transmitter finder searches for the marked bank contact and when found it connects the transmitter to wires? SI through 764 inclusive.



  When the relay 920 attracts, at the contact 921 it prepares at another point the starting circuit towards the transmitter. On contact 922, it prevents the attraction of the starting relay 940 if the key K2 has been actuated. Relay 970, at contacts 971 and 972, prepares the transmitter pulse circuit at another point.



   The operator then activates the key K2 of a free seeker circuit to attract the connection relay thereof, which links its position to the connection circuit considered. If we suppose that the key K2 of the circuit of the researcher of figs. 7 and 8 has been actuated, the connection relay 650 attracted under the action of its upper winding as previously described. When the connection relay 650 attracts, with its upper contacts it associates the finder circuit with the operator position, on contact 657 it remains pulled in series with relay 850

  <Desc / Clms Page number 95>

 on contact 658 it closes the power supply circuit of the starter relay 640 through the starter wire 638 which is grounded.

   The start relay 640 attracts and causes the finder to operate as previously described to select a delayed call junction circuit, thereby the relay 610 and the relay 579 attract. The relay 610 attracts in a manner identical to that which has been described previously;

   it connects the finder to the junction circuit for deferred calls and locks on itself. When relay 579 attracts, at contact 500 it puts the selector release wire to earth to prepare it for operation as 'it has been described previously, at contact 597 it connects the windings of the line relay of the selector to the terminals of the pulse springs of the transmitter,
The attendant then actuates the digit keys in accordance with the set number A1 and then actuates the transmitter start-up key to cause the transmission of the digits of the registered number. Under the action of the first digit, the selector in fig. 6 operates to select a free control circuit of a prepayment station in the well known manner.

   If we assume that the control circuit of FIG. 13 is the circuit that has been selected, we can see that the relays 1230 and 1240 attract in the following circuit: positive and negative, taken through the windings of the relays 1240 and 1230, normally closed contacts controlled by the springs 1221 and 1222, winding of the differential relay 1210 and left windings of the RC translator coil in fig.

   13, wires 1191 and II92, bank contacts 1181 and 1182 on which selector brushes 563 and 564 are engaged, normally closed contacts controlled by springs 587 and 585, normal contacts

  <Desc / Clms Page number 96>

 closed controlled by springs 592 and 594, contact 597, finder-finder bank contacts 501 and 502, finder-finder brushes 601 and 602, contacts 651 and 653, wires 632 and 634, springs 972 and 971 and their working contacts, con - tacts 973 and 972, son of pulses 761 and 762 leading to the transmitter. The control circuit of the prepayment station and the connector in fig. 13 now operate in the manner which has been described previously under the action of the digits transmitted by the transmitter to establish the communication to the line of set A1.



   When the transmitter has finished sending the last digit the relay 950 attracts in a manner identical to that which was previously described when the wire 763 is grounded. At contact 951, relay 950 closes a point which keeps relays 1230 and 1240 attracted. At contact 952, it places wire 751 to earth to attract relay 578 as described previously; at contact 953 it establishes its own blocking circuit and at the same time opens the circuit of relay 960 which consequently releases. When relay 960 releases, it removes control from the transmitter.

   When relay 578 draws to contacts 592, 593 and 594, it inserts the RC translator coil of the delayed calls into the circuit and places the upper winding of relay 577 across the terminals of jumper wires 1191 and 1192 to hold relays 1230 and 1240 attracted and to attract relay 577. At contact 595, relay 578 locks at grounded contact 598 and establishes the circuit which grounds the bias winding of relay 577. When the relay 577 attracts, at contact 591 it prepares the circuit of the AS supervision lamp at one point.

   When the subscriber of the set A1 answers, the relay 1270 draws into the loop of the line of the called subscriber in a manner identical to that which was previously described.

  <Desc / Clms Page number 97>

 and at contact 1271 it attracts relay 1220. Relay 1220 at contacts 1221 and 1222 reverses the direction of the current in wires 1191 and 1192 to cause the release of relay 577 of the delayed call junction circuit.



   The attendant then puts the deferred call key back in the rest position, which removes the first level marking from the researcher's vertical bench and releases relay 950 by disconnecting the earth from wire 1024. The researcher from the transmitter circuit operates to find the bank contacts that lead wires 771 to 774 inclusive and it associates the transmitter with the selector of the finder circuit in a manner identical to that previously described. The Operator then activates the keys of the digits corresponding to the number of set A and starts the transmitter as before. The operation from this point is identical to that which has been described previously and therefore only a brief description will be given.

   The first digit transmitted by the transmitter operates the selector of fig. I2 to enter a junction circuit, for example the junction circuit of fig. 6; the 2nd. figure operates the incoming selector in fig. 5 and the remaining figures operate the connector of fig. 5 to select station A. The relay 710 attracts when the transmitter has finished sending the pulses, it connects the converter coil Ra and places the upper winding of the relay 730 to the terminals of the junction wires 308 and 309 for cause the pull of this relay as described previously.



    When subscriber A responds, relay 310 draws into the subscriber's loop circuit and attracts relay 350 which reverses the direction of the current in wires 308 and 309 to release relay 30 and give supervision. as described above.

  <Desc / Clms Page number 98>

 



   In order to proceed with the collection of change at station A1, the operator operates the CCA collection key. Springs 1021 ground wire 1019, springs 1023 ground wire 1015 to pull relay 970. Springs 1022 connect the positive polarity of 110 volts to wire 1018.



  When relay 970 attracts, at contact 971 it connects the positive polarity of 110 volts to the following circuit: wire 634, searcher brush 602, bank contact 502, contact 593, lower right winding of the RC translator coil, contact 589, earth taken through the winding of the collection relay 575. Relay 575 draws into this circuit and at contacts 584 and 585 it grounds wires 1191 and 1192 through selector bays 563 and 564. When earth is connected to wires 1191 and 1192, differential relay 1210 attracts and relay 1240 releases, relay 1230 remains attracted.



  When the differential relay 1210 attracts, at contact 1211 it prepares the circuit of the collection relay 1295 at one point and at contact 1213 it keeps relay 1220 attracted.



  When relay 1240 releases, at contact 1242 it establishes the supply circuit for relay 1295. When relay 1295 attracts, at contact 1293 it prepares at one point the circuit which connects the "collection" battery to the wire. conversation, at contact 1297 it completes the circuit of relay 1200. When relay 1200 attracts, at contact 1204 it keeps relay 1220 attracted, at contact 1208 it bypasses contact 1241 to prevent the cut of the established connection, at contacts 1201 and 1202, it connects the positive polarity of 110 volts to the line wires 1285 and 1286 of the A1 station through the brushes 1275 and 1276 of the connector to attract the electromagnet 1308 and collect the deposited change.

  <Desc / Clms Page number 99>

 



   If Empress wishes to reimburse the change to the subscriber of the Al set, she momentarily activates the CRA reimbursement key, instead of the CCA collection key, to attract relay 970 and connect the negative polarity of 110 volts to the wire 1017. Relay 970 to contact 972 connects negative polarity of 110 volts to wire 632 to draw reimbursement relay 576 from the delayed call trunking circuit as follows: contact 586 grounded, reimbursement relay- ment 576, upper right winding of the trans- latrioe RC coil of the delayed call junction circuit, spring 592 and its contact on, contact 597, bana contact 501, researcher's brush 601, contact 611, contact 651, wire 632, contact 972, wire 1017, negative polarity of 110 volts.

   When the reimbursement relay 576 attracts, to contacts 587 and 588, it connects the negative to wires 1091 and 1092 through the selector brushes 563 and 564 to attract the differential relay 1210 and to make release relay 1230.



  When the differential relay 1210 attracts and the relay 1230 releases at the contacts 1212 and 1231, the supply circuit of the reimbursement relay 1296 is established.



  At contact 1298, relay 1296 attracts relay 1200 and the latter to contacts 1201 and 1202 connects the negative polarity of 110 volts in the following circuit: contact to work of spring 1294, contact to work of springs 1202 and 1201 , contact 1208, wires 1205 and 1206, brushes 1275 and 1276 of the connector, wires 1285 and 1286, station Al through the springs 1309 and the coil of the cash register relay 1308, earth. The electromagnet 1308. operates in the circuit described above and operates in the well-known manner for the reimbursement of the deposited change.

  <Desc / Clms Page number 100>

 



   After having established the link between the two subscribers, the operator returns the key K2 to the idle position and thereby completes the conversation circuit between the two subscribers. At the end of the call, when the subscriber hangs up his receiver, relay 310 releases and releases relay 350 which, at contacts 351 and 352, reverses the polarities on the junction wires 308 and 309 to make attract the polarized relay 730 in a manner identical to that which has already been described.



   On contact 731, relay 730 causes the OS supervision lamp to light. When the subscriber of set Al hangs up his receiver, relay 1270 releases, at contact 1271 it opens the circuit of relay 1220 and when the latter releases, at contacts 1221 and 1222, it reverses the polarities on wires 1191 and 1192 to cause the pull of the polarized relay 577 of the delayed call circuit. At contact 591, relay 577 completes the power supply circuit of the supervision lamp AS as described previously. The operator then actuates the key K2 and the release key RLCA again to release the relays 710 and 640 as described previously.

   Relay 710 at contact 711 opens the circuit of junction line relays 360 and 370 to release equipment at the remote automatic office as previously described. When the start relay 640 releases, it releases the relay as described previously and opens the circuit of relay 579. When the relay 579 releases, at contact 500 it releases the selector with which it is associated and at contact 598 it releases. releases the relay 578. When the relay 578 releases, at contact 594 it opens the circuit of the relays 1230 and 1240 as explained previously and due to the release of these relays the connection to the line of the station A1 is cut as described above.

  <Desc / Clms Page number 101>

 



   The circuit of figs. 1 to 14 having been described in detail, it did not seem necessary to explain the schematic circuit of FIGS. 15 to 17 inclusive since the devices and circuits of these figures have the same characteristics as the corresponding devices and circuits of Figs. 1 to 14 inclusive, the detailed descriptions which have been given above can therefore immediately apply to these diagrams.



   Figs. 15 to 17 inclusive give a diagram of the essential circuits for collection and. the reimbursement of, / currency, all other details relating to the establishment and supervision of the various connections having been intentionally omitted. It is believed that this way of representing the redemption and collection circuits in a schematic form will aid in understanding the invention.
 EMI101.1



    

Claims (1)

CLAIMS. ---------------------------- 1. A telephone system comprising two central offices linked by a trunk line and making it possible to establish the calls requested by a prepaid station via an attendant position located in one of the offices, in which the equipment is designed to give the operator the possibility of controlling the collection or reimbursement of change at the prepaid station connected to any of the offices, whether the prepaid station in question is the called station or the calling station. 2. A telephone system comprising two central offices linked by a trunk line and making it possible to establish the communications requested by a prepaid station via an attendant position located in one of the offices using a connection circuit comprising a finder and a connector associated with the operator position in which the necessary equipment is provided to allow the operator to control the collection or reimbursement of change at a connected prepayment station at any of the two offices. 3. A telephone system comprising prepaid stations in which one or the other of the two relays connected to a different talk wire through the winding of a third relay works in conjunction with the third relay to control the collection or reimbursement of change at the prepaid post. 4. A telephone system comprising two central offices linked by a trunk line and having in one of the offices a post repeater at <Desc / Clms Page number 103> prepayment intended to control the collection or reimbursement of change at a prepaid station for calls made in this office in which if a communication has been established from one prepaid station to an operator position of the other office the repeater of the prepaid station is automatically released from the circumstance? collection and reimbursement being controlled directly by the operator position. 5, A telephone system in which a prepayment station repeater is individually associated with the final selector by means of which the prepayment station is called and which is provided to control the receipt and reimbursement of change to the customer. prepaid station called. 6. A telephone system as claimed in claim 5 wherein communication is established between two prepaid stations via a prepaid station repeater associated with the calling station, an operator position, and a prepaid station. prepayment set repeater associated with the set called in series, means being provided in the operator position to allow this operator to control one or the other of the repeaters at will to cause the collection or reimbursement of change deposited at any calling or called station. 7. In a telephone system as claimed in claim 3, a trunk circuit connecting two central offices and operated in both directions in which the relays control the collection or reimbursement of change for incoming or outgoing calls. 8. A telephone system as claimed in claim 3 wherein the third relay <Desc / Clms Page number 104> is a differential relay which operates when a polarity is applied to the line which is used to release one or the other of the two relays to which it is connected and which works in conjunction with the released relay to control the collection or the reimbursement of the deposited currency. 9. A telephone system as claimed in claim 8 in which when the differential relay and one of the two relays are working in connection a determined polarity is applied to the two wires of the line while when the differential relay and the other of the two relays work in connection a different polarity is applied to the two wires of the line to respectively cause the collection or the reimbursement of the change at the prepayment station. 10. A telephone system as claimed in claim 1 or 2 wherein the repeater equipment / provided in the junction circuit between the offices and controlled by the operation of a key to the position of the operator for cause the inrush current to be sent to the remote prepayment station after the receiver has been hung up at this station. 11. A telephone system as claimed in claim 1, 2 or 3 in which a special tone at the prepaid station is sent to the operator when the short circuit normally placed at the terminals of a winding is temporarily removed. 'a voice coil by means of a group of relays placed under the control of a key from the operator's position which causes a new transmission of the tone on the line if the operator does not did not hear the first sending of this tone. 12. A telephone system as claimed in claim 1 or 2 wherein the line circuit <Desc / Clms Page number 105> a prepaid set designed to be connected to an operator's position through a searcher when a call is made, allows sending, in the event that the operator forgot to reimburse or collect the money deposited, a false call to the operator position when the communication is terminated, signaling this omission to the operator. 13. A telephone system as claimed in claim 12 wherein when the operator forgets to cash or refund the deposited change, the line relay of the prepaid station remains attracted such that when the receiver of the prepaid station is On hooked up, the searcher start circuit closes again to cause a false call to be sent to the attendant. 14. A telephone system as claimed in claim 1 or 2 in which the trunk circuit is provided with switching means causing a transient pulse of alternating current to be sent to the remote office to establish the link between. the two offices and to reverse the direction of the current at the junction later for the needs of the supervision. 15. A telephone system as claimed in claim 3, comprising a trunk circuit terminating in an automatic office in which one of the two relays serves to repeat the pulses received on the trunk when calls are received from that office. 16. A telephone system as claimed in claim 14. wherein the AC pulse transmitted over the trunk line attracts an AC relay connected to it. <Desc / Clms Page number 106> the arrival of the junction, this relay by attracting marks the junction as being calling in the seeker's bank of a seeker circuit associated with the operator position and completes a circuit starting the seeker in question so that it connects to the calling line. 17. A telephone system as claimed in claim 16 in which the finder has access to other lines in addition to trunk lines in which the tag circuits associated with some of the finder levels can be cut off by the finder. operation of a key so that only certain categories of calls can be directed to the operator position. 18. A telephone system as claimed in claim 16 in which a transceiver can be associated with the finder and the connector of a connection circuit to allow the operator to establish links between the calling and called subscribers. in the case of deferred calls. 19. A telephone system as claimed in claim 17 wherein as a result of the operation of a key from the operator position a deferred call circuit is marked in the searcher bank of the operator searcher circuit and in which the finder starts to search for this marking, the pulse wires coming from the recording transmitter being connected to the conversation wires which pass through the seeker to put in position a selector to which the deferred call circuit gives access. 20. A telephone system allowing the establishment of calls with prepaid sets in principle as described and shown in the attached plan. <Desc / Clms Page number 107> 21. A junction circuit connecting two offices and operated in both directions in principle as described and shown in the attached plan. 22. A telephone system in which researchers belonging to the series of researchers have access to different classes of subscriber lines, in order to give access to an operator's position, the researcher being chosen under the control. of an operator while the contact marking in the researcher bench is under the control of the subscribers, means being provided under the control of the operator to prevent calling lines, in some of these classes, from marking the lines. benches of researchers, which prevents finding these researchers and connecting them to these lines. 23. A telephone system in which researchers belonging to a series of researchers have access to different classes of calling lines and in which means are provided under the control of the operator to restrict the connection of these researchers to certain types at will. Only classes of calling lines.