GB413065A - Improvements relating to automatic telephone systems - Google Patents

Abstract

413,065. Automatic exchange systems. SIEMENS BROS. & CO., Ltd., Caxton House, Tothill Street, and DIXON, R. G., 162, Westmount Road, Eltham Park, both in London. March 7, 1933, No. 6888. [Class 40 (iv).] In a single-motion group selector provided with two sets of double-ended staggered wipers co-operating with four levels or rows of terminals W, X, Y, Z, the level to be used is determined by a preliminary digit which may effect wiper-selection or movement of the wipers through 180‹ or both. A second code selector driven by an electromotor DM and controlled by common apparatus including a digit switch DS is shown. After responding to the preliminary digit, the digit switch moves to a subnormal position and in accordance with the setting digit marks the group to be searched over by the selector, a single set of marking wires being connected to the appropriate terminals in the four levels. In the case of the level W, since no preliminary operation is required in the selector, a preliminary digit is unnecessary provided the setting digit always comprises a sufficient number of impulses to step the digit switch beyond its subnormal position. In all cases the setting digit may comprise up to 15 impulses. For the preliminary digit 1, relays G, P(i) energize over wipers DS 3, 4 and lock on the relapse of dialling relay C. Latch magnet LM operates and the selector rotates through 180‹ to the first terminals of levels X, Z, when test relay T pulls up in series with TA(ii) P(ii), and connects up TA(i). The windings of TA, P are in opposition, so that the former does not operate while the latter now falls back and in turn disconnects T. The digit switch steps to its subnormal position 5, in which relay E operates and completes a fresh circuit for dialling relay C in readiness for receiving the setting digit. If the preliminary digit is 2, relays G, F energize, and the digit switch moves to position 5 on the relapse of C. Relay E operates and connects up wiper-switching relay WS. If the preliminary digit is 4, relays F, P energize and the selector rotates through 180‹ as described above, while in addition wiperswitching relay WS energizes upon the operation of E. If the preliminary digit 3 is used to determine the level W, none of relays G, F, P energizes, and the digit switch merely advances to position 5. Otherwise, the digit switch advances to this position in response to the first five impulses of the setting digit, the group being determined by the succeeding impulses. After the setting digit has been received, the selector searches in the usual manner for an idle outlet in the marked group. If no idle outlet is found, the selector stops on the last terminals of the effective level, test relay T energizing in series with LC, which sends back a signal to the register-controller to effect rerouting and initiates release of the control circuit. The overflow meter of the appropriate group is actuated over one of wipers DS 4-7 in accordance with the condition of G, F. Specifications 388,173 and 411,456 are referred to.