Patent GB-265666-A (GB)
Title: Improvements in automatic and semi-automatic telephone systems
IPC: H04Q3/42
Filed: 1925-11-03
Abstract: 265,666. Standard Telephones & Cables, Ltd., Baker, J. H. E., Chanter, A. J., and Moscrip, W. R. Nov. 3, 1925. Automatic and semi-automatic exchange systems.-In a system employing register-controllers of the code-translating type, in the case of any irregularity of operation due to the dialling of an incomplete or non-existent designation or to the seized register-controller being faulty, the register-controller is released, and a second register-controller is seized with the line leads thereto reversed, so that a predetermined code is sent out to route the call to an operator, who may complete the call manually or explain to the subscriber the nature of his error. A first code selector having two sets of wipers which hunt simultaneously is described. Normal operation. When the selector is seized, line relay L and release relay B energize, and impulse relay G and change-over relay C (upper winding) are connected up. Relay P energizes and connects up the magnet (over lead RO) and switching relay K of the finder switch to the test wiper (over lead PR). On an idle registercontroller being found, relay K energizes, being no longer short-circuited, and the calling loop is now connected over lead PU to the impulse relay of the register-controller, while impulse relay G is connected across the line leads +OL, -OL. When a sufficient number of dialled digits have been received, the register-controller starts to send out the first train of impulses, which are repeated by relay G to the vertical magnet V. Change.over relay C (lower winding) holds in parallel during the train, and then falls back, connecting up the rotary magnet R. If test wiper P1 encounters ground on the first contact, relay Q energizes and lecks over a resistance to render it fast in releasing. If test wiper P2 encounters ground, relay G then re-operates, and acts as a stepping relay. If wiper P1 finds a free link, relay Q releases and removes the short-circuit over wiper P2 from test relay H, which energizes in series with relay G (now inoperative) and extends the connection. If wiper P2 finds a free link, test relay H energizes in the same way, and locks relay Q. The connection is completed in the usual manner, and relay D responds to reversal of line current to effect metering. Routing to an operator. This is initiated by the connection of ground to lead PU in the register-controller. Line relay L is consequently short-circuited and falls back, releasing relay B. Relay M (upper winding) now energizes. At the same time, the loop across leads +OL, -OL is broken, and relay G falls back, causing the switch to take one vertical step. Relay C relapses slowly, allowing test relav H to energize as if an idle link were found. Relay M locks up, and completes a fresh circuit for relay L over the calling loop, and relay B energizes again. When the register-controller releases, relay K falls back and connects up the release magnet Z to restore the selector to normal, and relay M relapses. Two-step relay O operates partially at the energization of relay M, attracting its armature 11, and on the relapse of this relay, operates fully and reverses the connection to leads +OL, -OL. The selector is now in the same condition as if it had just been seized, except that relay O is operated, so that a second register-controller is taken into use, and this, due to the reversal of leads +OL, -OL, sends out a predetermined code which routes the call to an operator's position. Such a register-controller is described in Specification 256,295.