Patent GB-264565-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/42
Filed: 1925-10-16
Abstract: 264,565. Standard Telephones & Cables, Ltd., (formerly Western Electric Co., Ltd.), Searle, A. M., Baker, J. H. E., Cameron, A. H., Moscrip, W. R., Chanter, A. J., and Wyndham, P. I. Oct. 16, 1925. Automatic and semi-automatic exchange systems; metering.-In a switch used in extending a call to an operator's position at which battery is applied to one of the speaking conductors to hold the switch against release upon the opening of the calling, line, an auxiliary holding relay is connected to the said conductor as a result of the de-energization of two slow-release relays on the opening of the calling loop. The invention is described as applied to a first code selector provided with supervisory arrangements for dealing with (1) the omission of the calling party to hang up, (2) a permanent loop on the calling line or delayed dialling, (3) forced release from the registercontroller, and (4) premature dialling. General operation. When the first code selector is taken into use the line relay L energizes the release relay B, which grounds the release wire RT and closes a circuit for a change-over relay C. Relay C energizes a combined impulsereceiving and stepping relay G which completes a circuit for an auxiliary holding relay P which in turn energizes a relay A, a starting circuit now being closed for the rotary magnet DM of the register-controller finder. When an idle registercontroller is engaged, connecting relay K energizes, locks up, closes an in-impulsing circuit over the lower winding of relay L, the calling loops, and the pulse wire PS, and transfers the circuit of relay G to the out-impulsing loop from the register. controller. The calling party receives the usual dialling signal, and the register-controller is set in the usual manner and subsequently transmits the first impulse series to the relay G, which repeats it to the vertical magnet V, the relay C being held during these impulses over the offnormal springs N3, 4. At the end of the digit, relay C relapses and energizes.the rotary magnet R which interacts with the relay G in the usual manner until an idle trunk is seized, whereupon the switching relay H locks energized and cuts through the out-impulsing loop. When all the digits have been sent, relay K is de-energized, frees the register-controller, unlocks relay P, reconnects both windings of relay L to the calling line, and completes a back-bridge supervisory circuit over relay A and the right-hand winding of a supervisory relay D. On the reply of the called party relay D pulls up and grounds the metering wire. Calling party omits to hang up. When the called party hangs up, relay D relapses and ground returned over the metering wire energizes the upper winding of a supervisory two-step relay M, which only closes its contacts 5, 6 and lights a supervisory lamp LP over the alarm wire SP. If the fuse in the common alarm wire SP blows this will not affect the metering circuit. Normal release and operator hold. On the calling party hanging up, the line and release relays L, B are de-energized, but before the relapse of relay B relay P pulls up and energizes relay C, and a circuit is closed for relay A which holds relay P over the homing wiper H independently of relay B, the subsequent relapse of which de-energizes relay C. Relay C de-energizes relay A which opens the circuit of relay P the relapse of which energizes the release magnet Z. If the call is to an operator's position the relay A is held) by battery on the positive speaking conductor and holds up relay P which maintains the release trunk RT grounded and the release circuit open. When the holding battery is removed relays A, P relapse and release occurs. All trunks busy. The wipers are rotated to eleventh contacts and cam springs S are operated. The switching relay H energizes in series with relay G, the register-controller discharges its remaining impulses and releases, and busy flash on the lead BF gives the calling party a disconnect signal. Permanent loop. If a fault develops, or the caller omits to dial, relays L. B, C. G, P. A and K become energized as before, but when time pulse ground is applied to the wire PS, relays L, B de-energize and a circuit is completed for the lower winding of relay M, which locks to the release wire, lights lamp LP, and connects the two windings of the line relay to the calling loop: relays L, B again energize. An attendant may force release by manually opening the circuit of the line relay. Normal release occurs if the subscriber hangs up, but if he dials, on the first relapse of relay L, relay G is de-energized, and the vertical magnet V steps up the wipers one step; the relay G however does not energize when the line relay pulls up since its circuit is opened by relay M. At the end of the digit, relay P relapses and opens the circuit of the relays C, A and the vertical magnet. Number obtainable tone NUT is now connected to the positive line and the caller hangs up to effect release. Forced release from the register-controller. This occurs consequent upon the breakage of the loop from the register-controller and the simultalleous grounding of the pulse wire PS. If no digits have been sent out from the register-controller the code selector is raised a step before the relapse of relay B. The subsequent relapse of relay B energizes relay M and de-energizes the relay C and the vertical magnet V. Relay C causes the relapse in turn of relays A and P, and a circuit is completed for the release magnet Z. When the offnormal springs 6, 7 close, the line relay L is connected to the calling loop and re-energizes relays B and P. Relay K relapses when the registercontroller clears, and energizes relay A, opens the circuit of relay P and energizes the vertical magnet V to raise again the wipers one step. When relay P relapses, relay A is de-energized and number obtainable tone NUT is connected up. If the register-controller has sent out one or more digits the operation is the same with the exception that the response of relay M de-energizes the switching relay H. On the relapse of relay H the test wiper P is grounded over the homing wiper H to hold the succeeding switch train busy for an interval. Premature dialling. In this case relays L, B, C, G, P and A are energized but the subscriber dials before relay K pulls up. On the first relapse of the line relay L, relay G de-energizes and closes a circuit for the vertical magnet V and for relay M, which opens the circuit of relay G and of the rotary magnet DM of the register-controller finder. At the end of the digit relays P, A, C relapse and number obtainable tone is connected up. Specifications 257,645 and 260,022 are referred to.