Patent GB-225630-A (GB)
Abstract: 225,630. Relay Automatic Telephone Co., Ltd., Inman, T. M., and Vanneck, R. G. Sept. 6, 1923. Automatic exchange systems.-In a districtoffice system employing impulse recorders, in the case of a non-local call, the recorder responds to the first digit or first two digits of the wanted number to select a trunk to the main exchange and transfers the digit or digits to a recorder thereat by the successive connection of battery and earth to one or other or both of the A and B wires. This operation may be repeated at the main exchange if the wanted line is in a distant exchange. Alternatively, a calling line may become connected over a trunk to a main exchange recorder, which in the case of a local call controls a recorder in the district office. In the arrangement described, a calling line in the district office is connected to a feed-relay group ABF, Fig. 2, and an idle recorder R1, Fig. 3, is taken into use, and extends the connection through the trunk connecting group CJ, Fig. 4, to an idle trunk terminating in a repeater REP, Fig. 5, at the main exchange. The first digit is transferred by means of the apparatus IT, Fig. 4, to an idle recorder R2, also shown in Fig. 3, at the main exchange, which then responds to the subsequent digits and controls the completion of the connection in the usual manner. The recorder is connected up ever the leads AF, BF, &c. when seized by a feedrelay group, and over the leads AR, BR, &c. when seized by a repeater. Additional relays shown on the left are provided for receiving the repeated first digit. Specifications 181,119, 211,231 and 212,682 are referred to. Extension of call to the main exchange. In the feed-relay group ABF, relays I, G, GX energize in turn, and relay FI operates in circuit 6, locks in circuit 4 and closes circuit 7 for relay RC1 corresponding to the first idle recorder R1 in series with relay PF, Fig. 3, which supplies battery to the recorder. Relays BK energize and connect up relay DM1 in circuit 9, whereupon relay ME1 energizes in circuit 10 and releases relay BK1. In response to the first dialled digit 5, say, relay BK5 becomes de-energized, and relay DC1 energizes and closes circuit 11 for relay MX2, thus energizing relays MC, MCX in the usual way. Relay SR5, Fig. 4, is connected up in circuit 12. Relay MCX closes circuit 19 for relay OTM, Fig. 4, which energizes relay OLM. Circuit 13 is completed for relay OJM associated with the first idle trunk to the main exchange, which locks and energizes connecting relays OJC, OLC. Switching relay IPH energizes in circuit 14 and connects the outgoing trunk to the apparatus IT. Repeating of the first digit. Relay SR5 is wired so as to connect battery to the A wire, and, when relay MCO is energized, earth to the A and B wires. Relay 1M therefore operates over the A wire in series with relay CIA, Fig. 5, locks and connects up relay 1MR. Relay RSS, Fig. 5, energizes in circuit 17 and completes circuit 21 for relay RC2 associated with an idle recorder R2 in series with relay PR, Fig. 3. Relay RC2 locks in series with relays PR, BY in circuit 22 and releases relay RSS. Relay PR prepares the recorder in the same way as relay PF, but in addition operates relay DC in circuit 23 and relay CH, to connect up the part of the recorder which receives the repeated first digit, and opens the energizing circuit of relay PF to prevent seizure by a feed-relay group. Relay RC2 extends the A and B wires to relays 1IA, 1IB, Fig. 3, which respond to the first marking condition, so that relay 1IA energizes in circuit 24 in series with relay HA, Fig. 5, which locks and connects up relay G to maintain circuit 22 independently of relay CIA. Slow relay LS does not operate. Relay HA also releases relays CIA and 1M, Fig. 4, so that relay MCO energizes and changes over the A and B wires in readiness for the second marking operation. Relay 11M, Fig. 3, is connected up by the energization of relay 1IA and completes circuit 29 for relay b, which locks. Relay 1ICO energizes in circuit 30 and locks, breaking circuit 24. Relay 1IA thereupon relapses, releasing relay 1IM and connecting up relay ICO, which switches over the A and B wires to relays 2IA, 2IB which respond to the second marking-condition. The release of relay CIA closes circuit 32 for change-over relay LSCO, which connects battery instead of earth to relays CIA, CIB. Marking earth on the A and B wires now causes the energization of relay CIA in circuit 36, and relay CIB in circuit 33 in series with relay 2M, which locks and connects up relay 2MR. Relay CI closes circuit 37 for relays HA, 2IA, while relay CIB close circuit 35 for relays HB, 2IB. Relays HA, HB locks and release relays CIA, CIB, 2M. Relays 2IA, 2IB complete circuit 38 for relay ICM, which closes a local circuit for relays 2IA, 2IB, short-circuits relays HA, HB, disconnects relay ICO and closes marking circuit 40 for relay HD 5.0, which locks. The contacts of relay DM1 are connected up differently in the recorders R1, R2, as indicated by broken lines. Relays DCC, DM1 are thus released. Relay DCC releases the part of the recorder which receives the repeated first digit, and relay DM1 releases relay DM2, closing circuit 41 for relay CH which locks and switches over the A and B wires to the part of the recorder responding to dialled impulses. Relay LSCO, Fig. 5, relapses, and relay LS operates in circuit 26 and switches through the A and B wires to the repeater REP. Release relay KBR, Fig. 4, energizes on relapse of relay 2M, and releases relay 2MR which disconnects relay KBR. Relay IPH also releases and circuit 20 is closed for relays OJB, OJC, OLB, OLC, RCO, Fig. 2. Relays OLM, OJM fall back and the recorder R1 at the district office is released, so that relays OTM, MX2, SR5 relapse. The feedrelay groups ABF is now connected to the repeater REP. Battery at a contact of relay I, Fig. 2, is connected over the A and B wires to relay I, Fig. 5, and the subsequent digits of the wanted number are repeated to the recorder R2, and the connection is completed in the usual manner. The marking conditions for different first digits are allotted arbitrarily. If, for example, the first digit is O, battery and earth are connected successively to the B wire, and the corresponding energization of relays 1IB, 2IB operates relays c, ICM, and the latter closes circuit 145 for relays 6CM, HD5.0. Relay 6CM connects up relay HD 6.C in circuit 146. Only one marking condition corresponds to the first digit 9. In this case battery is connected to the A and B wires, and relays 1IA, 1IB connect up relays 1IM, a, 1ICO, and then release, connecting up relay ICO. Relays 1IM releases slowly, and relay ICM does not operate since neither of the relays 2IA, 2IB is energized, so that circuit 191 is closed for relay d, which completes marking circuit 148 for relay 6CM, connecting up relay HD6C. In the apparatus IT, relays SR9, 1M, 1MR, MCO operate, whereupon release relay KBR energizes in circuit 193 to release the district office recorder R1 and extend the connection to the repeater R1 and extend the connection to the repeater REP. The relays SRO-9 may correspond to several distant exchanges.