Patent GB-276706-A (GB)
Title: Improvements in automatic telephone systems
IPC: H04Q3/00
Filed: 1926-04-30
Abstract: 276,706. Standard Telephones & Cables, Ltd., Wright, E. P. G., and Wain, D. H. April 30, 1926. Automatic exchange systems. - In a codetranslating register-controller, a Strowger-type switch set vertically by one of the exchange digits hunts rotarily to a position determined by a second Strowger-type switch set by the other two exchange digits, and the translated number is sent under control of the wipers of one or the other switch, or in some cases of both switches. In the circuit shown in Figs. 4 and 6, the switch W1 is operated by the A digit and W2 by the Band C digits, and translation is effected under control of the wipers W1 (maximum 5 digits) or W2 (4 digits) or both in turn (9 digits), the sending operations being started in the 2nd or 7th position of the switch SC. The automatic rotary setting of the A switch and the determination from which switch translation shall be effected are governed by the cross-connection of terminals engaged by the wipers W1 (6) and W2 (5 and 6). The number of codes that can be translated from the BC switch is increased by making the setting of this switch dependent on the A digit, a unit being subtracted from the vertical and rotary settings if the A digit has a value 2-5 and a unit being added to the rotary setting if the A digit has a value 6-9. This makes the 11th rotary positions of the BC switch available for translation, and also makes the 1st level and 1st rotary positions available in areas where code digits are precluded from having the value 1. In the modification shown in Figs. 7-9, provision is made for two-letter as well as three-letter exchange codes. The switch W1 is operated by the A and B digits and W2 by the C digit. Values 2-6 of the A digit correspond to twoletter codes and cause the switch DD to be driven automatically through the position in which the C switch is set, so that the 3rd digit operates the thousands register MR. Translation is effected either from the switch W1 or from W2, and since the translating wipers of the two switches are multipled the switch not required for translation is released before sending commences. Another modification is described in which some of the special features indicated above are omitted. In all cases a first digit of value 1 products a self-cancelling effect and a single digit 0 sets the A switch to the first terminals of its 10th level and routes the call to an operator. These and other discriminations dependent on the first digit are taken care of by the thousands register MR, which is operated in step with the vertical setting of the A switch and is released in time to record the thousands digit. Specification 271,128 is referred to. Figs. 4-6. Relay A is energized over the impulse wire PU and energizes B. Relay LC is partially and fully energized at the next closing and opening of the loop springs LS, and CC at the next closing and opening of the magnet springs MS. Relay CC drives the switch SC offnormal and is thereby unlocked. Action of the A, Band C digits. The A digit is repeated at R (5) through relay C and DD3 (1) to the vertical magnet V1 of the A switch and to magnet MR of the thousands register. Relay C unlocks TP and energizes DS, and C and DS relapse successively at the end of the digit. Assuming first that the digit has a value 2-5, the magnet DDM is energized, in the interval between the relapse of C and DS, over MR2, F (17), DS (11), C (7), PA (11), BK and drives the switch DD to 2nd position, and relay F is energized over F (12), K (7), DD2 (2), BK and locks itself and energizes magnet MZ to release the thousands register. The B digit is repeated over DD3 (2) to the vertical magnet V2 of the BC switch, but the first impulse is used up in energizing relay K, which is partially energized over its left winding by the arrival of the impulse and upon its cessation locks up fully over both windings and transfers the impulse circuit to V2. The relapse of relay C at the end of the digit unlocks K and advances DD to 3rd position. The C digit is repeated to the rotary magnet R2 of the BC switch, one impulse being deducted as before by the relay R, and the switch DD goes to 4th position, subsequent digits being recorded on the numerical registers MR - - UR. If, however, the A digit has a value 6-9, upon its termination the relav K is energized at once over MR2 and locks itself over K (18), F (8) and energizes DDM to drive DD to 2nd position. The B digit is repeated without deduction of an impulse to magnet V2, and upon the relapse of relay DS relay F is energized over F (12), DS (13) ,K (6), DD2 (3), BK and locks up, relay K remaining locked over K (14), DS (10), F (7), DD2 (3). In the interval between the relapse of relay C and the energization of F the magnet R2 is energized over F (5), K (6), DD2 (3), BK and gives the BC switch an extra rotary step. The C digit is repeated to magnet R2 and subsequent digits to MR &c. as before, the relay K being unlocked when DD goes to its 4th position. Automatic rotary setting of the A switch. The switch DD in its 4th position closes a circuit G, H (9), E, R1 (6), DD2 (4), energizing relay E (but not G) which energizes the rotary magnet R1 of the A switch, and the relay E and magnet R1 interact to rotate the A switch. If translation is to be effected from the A switch or from both A and BC switches, the terminal on which the wiper W2 (6) has been set is cross-connected to a terminal in the path of the wiper W1 (6), and when the A switch reaches this terminal it closes a circuit G, H (9), W1 (6), W2 (6), F (10), BK, so that relay E is short-circuited to stop the rotation, and relay G is energized, locks itself, and prepares a circuit for relay CC which is energized partially and fully at the next closing and opening of springs MS. If, however, translation is to be from the BC switch alone, the terminal engaged by the wiper K2 (5) is connected to a terminal in the path of the wiper W1 (6), and a circuit is closed G, H (9), W1 (6), W2 (5), H (left winding), F (10), BK. In this case also relay E is shunted out to stop the rotation but relay H is energized instead of G. Relay H locks itself, completes at contact 10 a self-interrupting circuit for magnet SCDM to drive the switch SC to its 7th position, and at contact 6 prepares a circuit for relav CC which is energized partially and fully at the next closing and opening of springs MS after the switch SC reaches its 7th position. Sending translated digits. Assuming first that translation is to be effected from the A switch or from both A and BC switches, the energization of relay CC closes a circuit SSDM. CC (9), MS, SC3 (2), G (6), F (10), BK to drive the switch SS. Relay SA is energized over the offnormal bank SS1, LC (9 and 11), BK and connects the springs LS across the outgoing loop + - in place of the right winding of relay D. When the wiper SS2 reaches the terminal grounded through G (6), SC3, SC2, W1 (1) and the usual cross-conecting frame, relay SZ is energized, locks itself, unlocks CC, reconnects the right winding of D across the outgoing loop, and closes a homing circuit for the switch SS. Relay SA then relapses and de-energizes SCDM so that the switch SC goes to its 3rd position, and relay SZ also relapses, restoring the circuit of relay CC so that the sending of the next digit begins. The interval between digits may be prolonged by the shunt-field relay D, which may be energized by reversal of the outgoing loop, e.g. when a coder is in action, and keeps the relay SZ locked up. Succeeding digits are sent under control of the wipers K1 (2-5) and W2 (1-4). Unrequired digits are skipped by jumpering the corresponding terminals to a wire TS12 to energize the right winding of relay H, which locks up and closes a self-interrupting circuit for SCDM over SC1 to drive the switch SC to its 7th position, whence it is driven by co-operation of the relays G and H to its 11th position, in which the sending of the numerical digits begins. If translation is to be effected from the BC switch alone the operations are similar except that sending starts in the 7th position of the switch SC and certain circuits are closed as a consequence of relay H being energized and G de-energized instead of vice versa. Release of register-controller. After the last numerical digits has been sent the switch SC2 grounds the wire TS11 to energize relay CO, which locks itself and unlocks relays B, LC, F &c, The register release magnets Z1 &c. are energized, and homing circuit closed for the switches SS, SC, in series with relay RA. The relays B, CO relapse successively and in the interval ground is taken off the wire PR to cause the disconnection of the register-controller, but ground is then re-imposed through CO (9), RA (7) until release is completed. Irregular releases. If the impulse springs MS or LS, are faulty the switch SC stays in its 1st position and the energization of relay F closes a circuit PA, SC4 (1), F (21), K (7), DD2 (2), BK. The relay PA locks up, grounds the busy wire PR independently of relay B, flashes the lamp LP, and connects the interrupter wire IE to relay TP which connects it to the right winding of relay M. Relay M grounds the impulse wire PU to cause the disconnection of the register-controller and then relapses, causing the release of relays A, B and consequently of all parts of the register-controller except relay PA. In the case of a non-existing code being dialled, the A switch rotates to its 11th position without relay G or H becoming energized, and the shaft-springs S short-circuit relay E, which sluggishly relapses and energizes the left winding of relay M to release the register-controller. In case of delayed dialling the relay TP is energized partially and fully by the closing and opening of the time pulse circuit TPW and connects this circuit to relay M. Release of A switch and thousands register if first digit = 1. The release magnet Z1 is en