Patent GB-198413-A (GB)
Abstract: 198,413. Western Electric Co., Ltd., (Western Electric Co., Inc.). Feb. 27, 1922. Automatic and semi-automatic exchange systems; coin-freed systems.-In a system in which toll calls between automatic exchanges are established by operators at special toll positions over two-wire trunks connecting the toll position to the exchanges, the collection or refund of the coins deposited at the calling subscriber's station is controlled by the toll operator over the conductors of the two-wire trunk itself, so eliminating the provision of special trunks or special connectors for this purpose. Special tone signals indicate to the operator whether the collecting or refunding means is operating properly. In the system described, connections both to the subscriber desiring the toll call and to the wanted subscriber are established bv toll operators over apparatus to that similar to that shown in Figs. 1-5. Each toll operator inserts the plug TT of her cord-circuit, Fig. 1, in the jack TSJ of an idle two-wire trunk 302, 303 provided with a repeater set, Fig. 2, and leading to a first group selector, Fig. 3, the connection being completed over a second group seletcor, Fig. 4, and connector, Fig. 5. The group selectors, which with the connectors are of the twoco-ordinate step-by-step type set under the control of the operator's dial D, are so modified that if, during their hunting movement, all the trunks in the selected level are busy, the operator's supervisory lamp 100 is flashed at a definite rate, whilst if the wanted line A is busy the lamp 100 is flashed at a different rate. If the wanted line is idle, the lamp 100 burns continuously and the operator depresses her ringing key RK to cause the connector to commence ring- ing. When the called subscriber replies, the energization of a polarized relay F2 extinguishes the lamp 100. The operator at the calling subscriber's end then throws her listening key LK and requests the subscriber to deposit the necessary coins. The depression of collect key 181 or refund key 180 energizes relays C4, D4 respectively, which transmit current from positive battery 447 or from negative battery 452 over the two talking conductors in parallel to energize the polarized magnet P of the coin box to collect or refund the coins. The system described is identical with that described in Specification 199,337, which claims other features of the system. Toll operator's cord circuit, Fig. 1. The insertion of the plug T in the answering jack J energizes relays E156, B162. Ringing current applied by the distant operator energizes relay A196, which de-energizes relay B162, lights the lamp 101, and locks up slow-acting relay E162 under the control of the listening key LK. If the call is for a subscriber reached only over a toll line terminating at a toll position at a distant office, the operator inserts the plug TT in a jack (not shown) leading to such office and operates her key RK to ring the distant operator who completes the connection. On the insertion of the plug TT, relay E155 energizes in series with relay E99 and disconnects the bridged supervisory relay B43, but if key k<1> is operated to disconnect the right-hand side of the cord from the operator's head set OT, relay B43 is again bridged across the cord and will respond to ringing current received from the distant toll operator and flash the lamp 100. If, however, the call is for a subscriber in the near-by automatic exchange, Figs. 3-5, the plug TT is inserted in the jack TSJ of an idle trunk, the idle condition being tested for by touching the tip of the plug against the sleeve of the jack when the battery conneetion on a busy trunk will give a click in the receiver of the head-set OT. In this case relays E99, E156, B2 energize in series, but marginal relay E155 does not energize and the supervisory relay B43 remains bridged across the trunk. Relay E99 disconnects the test wire of the head-set OT from the top of the plug. Relay repeater set, Fig. 2 ; first selector, Fig. 3. Relay C2, energizing over the circuit 200, 202, 120, B43, 121, 103, 204 in series with marginal relay A2 which does not yet energize, completes a circuit for line relay A3 of the first group selector, this circuit including the conductors 302, 303 and a bridge 206, 207, C2, 208, 209, 210, 211. The toll operator throws her dialling and monitoring key DK, energizing relay B34 which connects the head-set OT in a monitoring position across the cord. The movement of the impulse dial D from normal short-circuits relay B34 so energizing relay E72 which locks up and connects the tip conductor 103 to the impulse springs 108. Relay A2 now energizes and connects relay 12 in bridge across the trunk. Relay 12 energizes slowrelease relay D2 which, in turn, locks up relay E2. The first series of impulses are repeated by relay A2 over the trunk 302, 303 to the first selector, where they are repeated in known manner by the relay A3 to the vertical magnet 310. At the end of this series, the selector hunts in the usual manner under the interaction of stepping relay 314 and rotary magnet 318. When an idle trunk 351, 334 leading to a second group selector, Fig. 4, is reached, relay D3 energizes in series with relay 314, disconnects relay A3 and extends the impulse circuit over wipers 350, 333. If all the trunks in the selected level are busy, upon the eleventh rotary step the contacts 307 are operated to open the circuit of relay A3, whereupon the selector releases. Bridged relay 12 also falls back, causing the short-circuiting of relay D2, which falls back and completes a circuit 228, 282, 220, 222 for relay H2 which energizes, locks up, and opens the bridge across the trunk to prevent the repetition of further impulses. Relay H2 also connects up the interrupter 223 to the circuit C2, 201, 222. thus intermittingly short-circuiting the resistance 200 so that when, at the conclusion of the dialling operation, key DK is restored and relay E72 deenergizes to connect up relay B43, the lamp 100 is flashed at 60 times per minute to inform the toll operator of the failure to find an idle trunk. Second selector, Fig. 4. Upon the extension of the connection over brushes 350, 333, line relay 4 energizes over the circuit 400, 402, 405, 302, 303, 406, 408, 453, 409 in series with relay 12 and energizes the slow-release relay Q4. Relay J4 energizes over the circuit 413, 411, 403. The second series of impulses is repeated by relays A2, 04 to the vertical magnet V4, and at the end of the series, the wipers hunt over the selected level in known manner under the interaction of stepping relay S4 and rotary magnet R4. When an idle trunk is reached, relay M4 energizes in series with relay S4, grounds the test wiper 425 and extends the connection to the connector, Fig. 5. If no idle trunk is found, contacts Y4, operated upon the eleventh rotary step, release the selector, de-energize relay 12, and cause the flashing of lamp 100 in the same way as described above for the first selector. Connector, Fig. 5. The connector shown serves for both local calls which are completed over the three upper conductors and for toll calls completed over conductors 510, 546, 500, 550. When relay M4, Fig. 4, operates, relay J4 remains energized over the circuit 413, 432, 433, 500, 502, 550, 425. Line relav A5 energizes over the circuit 505, J5, 507, 546, 430, 428, 440, 441, 442, 429, 510, 512. Slow-release relay J5 also energizes in this circuit and locks up over the front contact of slow-release relay B5, which also grounds the test wire 517 connected to terminals in the banks of local selectors. The tens impulses are repeated by relays A2, 04, A5 to thevertical magnet 518 in series with a slow-release relay 519 which at the cessation of the impulses prepares a circuit for the rotary magnet 528 to which the units impulses are repeated in the usual manner. Busy test and release. During units selection, slow-release relay E5, energized in parallel with the rotary magnets, connects the test relay G5 to the test wiper 527, and if the wanted line is busy, the test relay energizes and locks up. (In the case of a local call, this relay would connect up busy tone from the transformer 545, but in the case of a toll call, this tone is not used, being cut off by relay J5). When the toll operator restores the key DE, interrupter 233 is connected up to flash the lamp 100 at 120 times per minute, in response to which the operator removes the plug TT, so releasing the automatic switches, operates key R<1>K<1> to ring the distant operator and withdraws the plug T. Ringing arrangements. If the wanted line is idle, relay G5 is not energized and relay H5 energizes over the circuit 516, 531, 530, 529, 527 and battery connection to the test terminal 526 of the wanted line A. Relay H5 locks up and relay K5 energizes over armature 532 and the grounded conductor 550, the energization of relay K5 opening the previously-traced circuit for relay J4 which releases. Relay B4 energizes over the circuit 344, 422, 403 and completes a new ground connection over conductors 345, 413, 500 to hold up the slow-release relay F5, which was energized over the front contact of relay 519 during the tens selection and locked up over the back contact of armatures 502. The restoration of key DK at the conclusion of the impulses connects relays B43, C2 in series with relay A2, which thereupon de-energizes to disconnect the bridged relay 12, leaving a bridge through the polarized relay F2. The reversal of battery and earth connections to the line conductors produced by the operation of relay B4 causes relay F2 to energize and complete a circuit for relay G2 which energizes and locks up. Relay B43 now energizes over conductors 204, 303, 350, and 202, 302, 333 and lights the lamp 100, in response to which the operator throws her ringing key RK, which applies ringing current to energize the rela