Patent GB-328610-A (GB)
Title: Improvements in or relating to switching arrangements for use in automatic or semi-automatic telephone systems
IPC: H04Q3/42
Filed: 1929-01-31
Abstract: 328,610. Standard Telephones & Cables, Ltd., and Baker, J. H. E. Jan. 31, 1929. Automatic exchange systems. - In a single-motion switch responsive to two trains of impulses, the consecutively-numbered lines of each of two or more groups are connected at regular spaced intervals in the terminal banks, and the impulses of the first train advance the wipers one step per impulse, or one step each alternate impulse in the case of a switch with two sets of wipers, while the impulses of the second train cause the wipers to advance, directly from the position they occupy as the result of the first train, two or more steps per impulse depending on the number of groups. All the steps are of uniform length. In the simple twogroup arrangement shown in Fig. 1, lines numbered 11, 12, 13, &c., are connected to the even terminals commencing at 4, and lines numbered 21, 22, 23 &c. are connected to odd terminals commencing with 5. Relay, A responds to the first train (1or 2) and magnet S operates in series with relay C which completes an initial circuit for two-step relay E. At the end of the train, C falls back and E operates fully over E5. If the digit is 1, D energizes over wiper C and locks up before E operates. The first relapse of A during the second train operates S over A1, B1, C, E1, D (1 or 2), and on the re-energization of A, S again operates over A1, E2, D (2 or 1), so that the switch advances two steps per impulse. The arrangement shown in Fig. 2 comprises a switch with two sets of wipers (only the control wipers are shown), each having access to five groups of lines. In the case of one set giving access to lines having an odd first digit, lines 11, 12, 13 - - 19, 10 are connected to terminals 7, 12, 17 - - 47, 2, the remaining groups being similarly connected to series of terminals commencing at 8, 9, 10 and 11 respectively. When relay A falls back on receipt of the first impulse, relays S and E (lower), energize in parallel and two-step relay G operates over its upper winding to close contacts G5. Relay C holds during the train, and when A pulls up again E holds over its upper winding, D and F (upper) operate in parallel circuits, and F opens the original circuit of E. When relay A falls back at the next impulse, E relapses and opens the original circuit of F which, however, holds over its lower winding. The next operation of A releases F which again prepares the circuit of E. Relays E, D are thus simultaneously in operated condition when A re-operates at the end of each odd impulse, and the back-stroke magnet S operates when its circuit G6, E2, B3 is opened by the relapse of E at the commencement of each even impulse or at the end of the train. Relay D is a wiper switching relay discriminating between odd or even digits and, when G operates. fully on the relapse of C, remains locked over G4, D1 if the digit is odd. Relay G also connects ground from C1 to wiper C and thence to one or a combination of relays J, H, I according to the value of the first digit and any relay so operated locks up over B(2), ground being connected from B3 over E2 and contacts of relays J, H, I to the terminal on which wiper D is resting and thence over G7 to operate relay M which at M2 opens the self-interrupting circuit of magnet S. Assuming the dialled number to be 63, the switch at the end of the first digit will be standing on its fourth terminals and relay H operated. When relay E responds to the first impulse of the second digit, it transfers the ground from terminal 4 to. terminal 9, M falls back and the switch steps on until M re-energizes when it reaches terminal 9 and opens the driving circuit. Relay E falls hack and transfers the ground to terminal 14 so that M relapses and the switch steps on once more. The switch then takes five steps for each impulse, and when the third impulse comes in, E operates and the switch steps and stops on terminal 19 which corresponds to lines 53 or 63. As the wanted line is assumed to be 63, relay D is not operated and the wiper set of the even-firstdigit lines remains connected up. If the second digit is 0 the switch makes a complete revolution and drives over the home or first terminal to the marked one of terminals 2 - - 6. On release, B falls back and releases M which closes the circuit of S, and when the switch reaches the home terminal, which is now grounded at B3, M reoperates and short-circuits G over wiper C so that D and M fall back.