Patent GB-271128-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/42
Filed: 1926-01-18
Abstract: 271,128. Standard Telephones & Cables, Ltd., Searle, A. M., and Baker, J. H. E. Jan. 18, 1926. Automatic exchange systems. - In a register controller which receives all three name digits one of the switches that receive the name code may be re-set in accordance with the whole code. If there are more codes than can be recorded on this switch others are provided the first digit determining which is to be used for recording the whole code. In the system described, the A and C digits are received on a Strowger switch and the B digit on the units register. The AC switch takes an automatic rotary step at the end of the A digit and in this position controls the routing of zero calls, releases itself if the digit is 1 and selects the switch which is to be set in accordance with the whole code. When the code has been registered, the sender control switch moves automatically to a position determined by the position of the AC switch which is then released and stepped vertically in synchronism with the units register until the latter reaches normal. Finally the AC switch receives rotary impulses synchronously with the sender control switch until the latter reaches a predetermined position. The sender control switch then takes a further step by itself and impulse transmission begins. Reception of name code. When the register controller is seized, relays A, B pull up, dialling tone is sent from DTW over PU, the interrupters on MS, LS are started over MST, and the twostep relays LC, CC in known manner move the sender control switch SC one step from normal if the springs are in order. The name digits are repeated over CO-11, A-5, C, wiper DD3 of the digit distributor DD to the vertical magnet V1 of the Strowger switch AC1, the magnet UM of the register UR and the rotary magnet R1. Relay C energizes a sluggish relay DS over BK and on falling back at the end of each digit energizes the digit distributor magnet DDM over DS-13, BK. At the end of the first digit it also energizes the magnet R1 over DS-11, DD2, BK, to bring the wiper 1 of the AC switch on to one of the first terminals shown at X. In the case of certain of A digits, this completes a circuit for a relay DC over SC4, DD2, BK, and relay DC locks up and arranges for the magnets V2, R2 of a second Strowger switch AC2 to be operated instead of magnets V1, R1 to register the whole code as described below. Setting office register. In position 4, the switch DD completes a self-interrupting circuit DD2, G-8 for magnet SCDM of the sender control switch which advances until this circuit is broken by relay G which pulls up in a circuit SC2, PTF (which is jumpered arbitrarily to the bank of wiper 6 of switch AC1), DD2, locks itself and energizes the release magnet Z1 of switch AC1. When the off-normal springs ON are restored, relay F pulls up over LC-31, G-11, locks itself and connects relay CC in circuit with springs MS. Relay CC pulls up in two steps locks up over SC3. F-14, K-6 and diverts the impulses over CC-11, K-15, DC-12 to the magnet VI (or V2 if relay DC is energized) and over CC-11, K-15, CC-8 to the magnet UM of the units register, which, on reaching its last terminals energizes relay B which locks up, unlocks relay CC, stops the vertical magnet, disconnects the upper winding of relay F and energizes the release magnet UZ of the register UR in series with the lower winding of relay F which is thus held until the off normal contacts UR1 change over. Relay K also completes circuits over the interrupters IS1, IS2 for the sender control magnet SCDM and the selected rotary magnet R1 or R2, which advance until wiper SC2 in position 14 energizes relay E which locks up, breaks the above driving circuits but at E-8 makes a further circuit over SC1 in which the sender control switch moves one step by self interruption. Transmitting route code. In position 15 wiper SC3 re-energizes relay CC which locks up and diverts the impulses from MS over CC-11, K-15 to the magnet SSDM of the sending switch which at its first step energizes the pick up relay SA which in conjunction with the stop relay SZ controls the transmission of the route code in known manner in accordance with the jumpering of the banks of the office register at the frame TS. Terminals for which no digit is to be sent are jumpered to 18 to extend the marking ground over LC-10 to the homing bank SC1 of the sender control switch. Numerical digits; normal release. The numerical digits are registered and transmitted in the usual wav after which the sender control switch over SC4 energizes the relay CO which cuts off relays B, LC and energizes the release magnets of the digit distributor and 'the number registers in a circuit ZP-11, B-19, CO-13. Relay B by removing ground from the test wire, cause the first code selector to switch through. Homing circuits are made over LC-10, LC-29 for the sender control and sending switches and, on the relapse of relay B, relays G, E. K fall back and the release magnet Z1, Z2 of the office register is operated. Relay CO falls back shortly after relay B, Zero calls. The AC switch on its tenth level energizes relay MB which energizes relay E and prepares for the transmission of a special code. The sender control switch is driven at once to 14 (in which relay G pulls up) over MB-15 and over E-8 to 15 in which impulse transmission begins. Relay G releases the AC switch. Accidental impulses. On its first level, the AC switch energizes relay ZP which releases the AC switch and the digit distributor and then falls back. Calls to coders. Relay D which is energized by reverse current until a coder is ready holds the stop relay SZ over D-6, SC-4 to delay transmission of the next code digit. Standstill release. Relay TP pulls up in two steps at each pulse in the wire TPW after the register controller is seized and connects the pulse wire to relay M which, unless the subscriber dials before the next pulse, opens the outgoing loop and grounds the wire PU to release the register controller from the first code selector. If the subscriber dials now, he gets NU tone as described in Specification 256,295. When the pulse goes off, the relays A, B release the register controller. Spare codes are jumpered to SN to energize relay M and release the register controller. Exchange attendants signals and alarms; statistical metering. The lamp LP glows while the register controller is off-normal except while it is receiving impulses. In case of spring failure the digit distributor at the end of the first digit completes a circuit DD2, SC4 for relay PA which locks up, flashes the lamp LP, puts an alternative busy mark on the register controller and connects rapidly interrupted ground IG to the time pulse relay TP which releases the register controller as in the case of delay in dialling. On the relapse of relay B after the register controller has finished, a short circuit at B-19 is removed from relay RA which pulls up in series with the release magnets of any switches that have failed to release, operates an alarm on AL and on the relapse of relay CO restores the guarding ground to the wire P. The meter TM is operated when relay CO pulls up to release the register controller.