Patent GB-191202671-A (GB)
Title: Improvements in Automatic and Semi-automatic Telephone Circuits.
Filed: 1912-02-01
Granted: 1913-02-03
Abstract: 2671. Siemens Bros. & Co., [Siemens & Halske Akt.-Ges.]. Feb. 1. Automatic exchange systems.-When two interconnected automatic exchanges comprise, say, 3,000 and 6,000 subscribers, so that all the subscribers can be represented by numbers having no more digits than would be required for either exchange separately, arrangements are provided by which the impulses representing the first digit of the wanted subscriber's number operate a selector in each exchange. This enables all connexions from one exchange to the other to be made over a single set of junction lines, without prefixing an extra digit to distinguish the two exchanges. In the arrangement shown in Fig. 1, a selector GW at the exchange of the calling subscriber T is set simultaneously with a selector at the end of the leads av, bv, which run to a distant exchange. One or other selector is then automatically released according to the level to which they are raised. In the arrangement shown in Fig. 2, a selector is actuated at both exchanges only when the wanted subscriber is at the distant exchange. Certain levels of the bank terminals of the selectors W at the exchange I are allotted to the service of the distant exchange II, the other levels being appropriated to local connexions. When a selector W occupies a set of terminals in one of the " junction " levels, a distributing-switch WS selects a disengaged junction-line av, bv. Each junction-line terminates in a two-co-ordinate call-finding switch W1 at the exchange I, and in a selector W2 at the exchange II. The call-finder W1, under control of a testswitch ZS, raises itself to the same level as the selector W and then hunts round until it finds the line occupied by the selector W. The impulses which raise the switch W, are repeated to the distant selector Wz, which is thus raised to the same level as the selector W. First arrangement, Fig. 1. A calling subscriber T is connected by his preliminary selector VW to an idle trunk which branches to two other preliminary selectors VW1, VW11, the former of which connects him to an idle selector GW at his own exchange while the latter connects him to a junction line av, bv ending in a selector at a distant exchange. The first set of impulses sent by the subscriber T is repeated by a relay set Ue to both selectors, and raises them to the same level. The selector GW has a contact S which partakes only in the vertical motion of the switch-shaft and which engages a set of contacts p0, p1, &c., of which p0 corresponds to a first idle step and p1 &c. to the various levels of bank terminals. At the first vertical step, a circuit is closed over an off-normal contact 38, contact p0, S, relay E, and contacts 33, 26 in parallel. The relay E locks itself up and closes circuits through both windings of the differential relays F and G, which do not respond. At the first rotary step of the selector GW, contacts i1, i2 are closed, connecting ground and battery respectively to the contacts p1 &c. which are connected in two groups corresponding to local and junction-line connexions. Thus, according to the level to which the selector GW has been raised, either ground or battery is connected to the contact S and leads d1, d, and thereby one winding of one of the relays F, G is shortcircuited, and one of these relays is consequently energized, open circuiting the relays C1, P1, or C2, P2 so as to release the preliminary selector VW1 or VW11 and the selector seized by it. Second arrangement, Fig. 2. If the selector W at the exchange I is raised to one of the levels allotted to the distant exchange II, a relay R is energized and closes the circuit of a relay J, which closes a circuit through a switch WS to the relay G of a disengaged junction-line av, bv. The relay G locks itself in series with a relay K and solenoid Z1, both of which are consequently energized. The solenoid Z1 now rotates a testing switch ZS under control of an escapement-magnet Z, which receives current-impulses from an interrupter U over contacts of the relays J1, K. These impulses also pass through a vertical magnet H1 of the call-finder W1 and through a relay A, which controls the vertical magnet H2 of the distant selector W2. At the first vertical step of the call-finder W, the off-normal contacts 25, 26 are closed, energizing the magnet S, which moves the switch WS forward until it comes to the next disengaged junction-line. When the switches W1, W2 have been brought to the same level as the selector W, a circuit is closed through the relays J1, K1, the testing-switch ZS, and the relays R and P. The relay J1 is energized, stopping the switches ZS, W1, and W2. and closing a circuit for the rotary magnet D1. The call-finder W1 now rotates until it reaches the line occupied by the selector W, whereupon the relay Tr is energized, which short-circuits the relay R and thereby increases the current in the circuit of the relays J1, K1, sufficiently to energize the relay K1, which did not previously respond. The relay K1 opens the circuit of the relays G and K and of the solenoid Z1. The testing-switch ZS therefore restores itself, and the relay G, by cutting out the rotary magnet D1, brings the call-finder W, to rest. The rotary motion of the selector W2 is initiated by a relay B, which is energized in parallel with the magnet D, and locks itself up over the off-normal contact k. When an idle line is reached, the test-relay P, is energized and cuts out the rotary magnet D2. Specification 6654/10 is referred to.