Patent GB-261465-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/42
Filed: 1925-08-18
Abstract: 261,465. Standard Telephones & Cables, Ltd., (formerly Western Electric Co., Ltd.)., (Deakin, G.). Aug. 18, 1925. Automatic and semi-automatic exchange systems.-In a system in which some subscribers set up calls automatically while others need the help of an operator, both kinds of call are extended over the same second line finders 2LF to a connecting circuit from which a lateral connection is made to an idle register controller R which in the case of one kind of call is set in known manner by the subscriber, and in the case of the other kind of call automatically extends the call to an operator's position OP. The operator then sets the register controller by means of her key set KS and sender S1(S2 or S3). The circuits of the finders, connecting circuit CC and register chooser RC may be similar to those described in Specification 256,554. In the system described the register controller is used in setting up the connection only as far as the wanted office, the call being completed by an operator, but the invention is applicable to systems in which the whole call is set up automatically. Each first line-finder 1LF gives access only to subscribers of one class, and those giving access to the semi-automatic class are indicated by grounded terminals in the bank of an extra wiper X on the second line-finders. When an idle register controller is seized, the connecting circuit sequence switch moves from position 3 to position 5, and the sequence switch in the register moves from position 1 to position 3. When a semi-automatic call is made, therefore, the relay X1R disconnects the dialling tone coil and connects up the test relay X3R, and driving magnet Ps of the sender selector SC. When an idle sender is found, relay X3R shunts the high-resistance winding by a low-resistance winding in series with relay X4R which pulls up. Relay JAR in the sender energizes relays X5R, X2R which lock up and starts the switch TS. Relay X2R. switches over the impulsing wires from the instepping relay ISR over wipers o, p, to terminals in the two upper banks of the switch TS and connects the relay ISR over wipers m, n, to the impulse circuit of the sender. When the switch TS finds the calling sender, relay TR stops it, lights lamp PL, and energizes relay OTR to connect the operator's telephone set to the calling line. The operator on enquiry presses the key OK corresponding to the wanted office energizing relay KAR which locks up in series with relay AR. Relay AR energizes the impulse sequence switch RA and releases relay JAR, whereupon relays TR. OTR fall back, and if either of the other registers has a waiting call the switch TS hunts for it. In the register controller, relays X3R, X4R fall back, but the sender is still non- selectable because relay AR is energized. As the switch RA rotates, it first, in position 4, energizes relay S1R which locks up and puts the instepping relay under control of the cams B - - F. These are arranged to send out from 1 to 10 impulses over the correspondingly numbered leads between position 5 and 15 of the switch RA. The first digit depends on the jumpering of terminal 13. In the silent period between positions 15 and 5 the register switches over. In position 3 at the second revolution, relay S2R locks up to control the sending of a further, digit in accordance with the jumpering of terminal 12. Relay S3R similarly controls the transmission of a third digit. In position 16 of the third revolution, relay RAR unlocks the relays S1R - - S3R, KAR and AR and energizes relay X6R which unlocks relays X2R, X5R and then falls back. The register controller is thus disconnected from the operator's sender. Relay RAR holds up over G and disconnects the q terminal to keep the sender non-selectable until it reaches normal. If fewer than three digits are to be sent, the terminals 11 or 11 and 12 are connected directly to the m terminal to hold 1SR during the unnecessary rotation of the switch RA. Automatic subscriber neglects to dial. The timing device TA by which, ordinarily, the register controller is released when a subscriber fails to dial may be arranged as indicated to energize the relay X1R to cause the call to be switched through to the operator as in the case of non- automatic subscribers.