Patent GB-523266-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/58
Filed: 1938-12-29
Abstract: 523,266. Automatic and semi-automatic exchange systems. POLLAK, J. E. (Fides Ges. fur die Verwaltung und Verwertung von Gewerblichen Schutzrechten.). Dec. 29, 1938, No. 37783. [Class 40 (iv)] In a tandem R.C.X.U2, each of the finderconnector links AS-LW is provided with an auxiliary switch EW which, when the settings of the finder and connector indicate that the call is one between subscribers in one of the remoter offices such as U1, hunts for the junction over which the call arrived, the connector being stopped on the first terminals of the level concerned. Subsequent impulses are repeated over the wipers of switch EW. In a modification, not described in detail, the switch EW is reached over the connector wipers, the first terminals in all junction levels of the talking banks being multipled together and connected to the EW wipers instead of being left blank as in the system described. As shown, the exchanges are controlled by an operator but they may be controlled by a central office register-controller. Circuit details. An A.C. calling impulse received over the junction a2/b2 from U1 energizes the line relay R which locks up and energizes relay Mt in the first idle link. Relay S then energizes the forward-drive finder-magnet Das which interacts with R1(i) until the circuits of both are broken by the test relay P which pulls up in series with cut-off relay T and a holding winding of the line relay and switches through. The starting wire is then extended by Sp to the next link, and a relay An sends an A.C. signal over the junction ao/bo, which leads to the main office or to a similar tandem R.C.X., and causes a switch AW on the end of the junction to hunt for the link, which is marked by the connection of G to the d-bank, under control of Po. G pulls up in the test circuit, when the link is found, and releases An to terminate the calling signal. Po extends the talking circuit and marks the link busy. When the operator plugs in, J, C, C1 pull up. If the subscriber is still on the line, a relay like Y at the originating office is connecting battery to wire b2 and relay Y at U2 is energized and is connecting battery to junction wire bo to notify the operator. In the absence of this notification the operator energizes E over the wire bo and this signal is repeated to the originating exchange and causes the subscriber to be rung in known manner. Relay J repeats the first digit to vertical magnet H and to relays V, V1 of which the former follows. the impulses and the latter holds throughout the train. On levels containing junctions, shaft contacts 29dk energize Q which locks and completes a circuit for rotary magnet D when V1 falls at the end of the digit. Relay K pulls up when rotary springs 100 wlw change over and energizes B in place of Y over the junction wire b2. If the call is a reverting one, the switch is stopped on the first terminals by the operation of test-relay Pl in series with wiper d of the call finder and relay T1 and the latter energizes the driving magnet Dew which interacts with relay Rl (ii) to drive the auxiliary switch EW to the position marked by wiper e of the call-finder. In this position it is stopped by relay U which disconnects the answering end of the link talking circuit, releasing B, and switches the calling end through to the wipers of EW which is now standing on the calling junction. Subsequent digits are repeated by J over a2 and the reply signal is repeated over the various bwires involved by relays such as Y. When the operator withdraws relay J falls, V, V1 pull up momentarily shunting out C and then fall back together with P1, T1, U, P, R, T. The final selector is restored to normal but EW and the finder remain in the position to which they were set. On the restoration of the rotary off-normal springs, G, Po are released to free the junction ao/bo. At the originating office the relapse of J similarly energizes V, V1 but relay S which was energized by the called subscriber's reply prevents shunting out of relay C. In the case of calls to subscribers in U2 the switch LW responds to a second digit. In the case of calls to another R.C.X. the rotary magnet interacts with R1 (ii) until an idle junction is found, relay p in this case pulling up in series with the cut-off relay T of the junction. Unsuccessful calls. If the called party fails to reply the operator can release J and energize E. Release of the final selector end of the link takes place as before but the call-finder switching relay is held by E. The operator can then re-operate V, C, Cl to put herself in come munication with the calling subscriber.