Patent GB-191408800-A (GB)
Title: Improved Circuit Arrangements for Telephone Systems.
Filed: 1914-04-07
Granted: 1915-07-08
Abstract: 8800. Siemens & Halske Akt.-Ges. April 7, 1913, [Convention date]. Automatic and semi - automatic exchange systems.-In systems involving the temporary association of auxiliary devices, such as registercontrollers, with the selectors which establish the talking-connexions, a number of auxiliary devices are arranged to be available in common to a number of groups of selectors, the first auxiliary device being available to the frst selector in each group, the second auxiliary device being available to the second selector in each group, and so on, and means are provided for preventing an idle selector from being taken into use unless the auxiliary device to which it has access is also idle. By this arrangement, the auxiliary devices are made more widely available. The Specification refers to the application of the invention to (1) registercontroller and translating systems, (2) systems in which separate setting and speaking paths are made use of, (3) systems with means for preventing the release of a subscriber's line, over which a fire-alarm signal is being sent, until the fire-call has been noted at the exchange, (4) systems with auxiliary devices for controlling the subscriber's meter in junction and trunk working, and (5) call-finder systems in which two-coordinate finders are employed, the vertical movements of which are controlled by auxiliary tens-testing switches. The last of these applications is shown in Fig. 2. The first tens-testing switch ZS1 is connected by leads 26, 12, 27 to the first call-finder AS, in each of a number of groups, the second tenstesting switch (not shown) being connected to the second finders, and so on. In each group a distributing-switch WS1 pre-selects an idle call-finder which has an idle tens-testing switch associated with it. When the subscriber N25 lifts down his receiver, the group relay An1 energizes the relay F of the pre-selected callfinder AS1. The relay F (1) locks itself up, (2) short-circuits the relay An1 so that the line relay R25 receives more current and becomes energized, and (3) completes an interrupter circuit through the rotary magnet Dz of the tens-switch ZS1 and the vertical magnet H of the can-finder. The closure of the contact k3, when the call-finder leaves its normal position, sends the distributor WS1 forward in search of the next idle finder associated with an idle tens-switch, and the closure of the offnormal contact 23 of the tens-switch ZS1 grounds the wire 27 so as to prevent the other callfinders associated with the same tens-switch from being selected for dealing with calls in other groups. After the first vertical step of the call-finder the locking-circuit of the relay F is opened at the contact k1, but the relay F is kept energized by a slow-release relay V, which is now connected in series with the magnets Dz, H. When the call-finder reaches the level in which the calling line is connected, the relay Pz is energized over the contact 29 of the relay R25 and opens the circuit of the magnets Dz, H, V. After a moment, a sluggish magnet Mz in parallel with the magnet Dz releases its armature and restores the tensswitch ZS1 to normal, and, in consequence of the opening of the contact 23, the other finders associated with the switch ZS1 become again available for service. At the same time, the relay V de-energizes, completing the circuit of the rotary magnet D and unlocking the relay F so that the connexion between the switches ZS1, AS1 remains severed. When the call-finder reaches the terminals of the calling line, the relay P open-circuits the magnet D, and the relay T25 cuts out the relay R25' The relay A is now energized and closes the circuit of a slow-release relay U1, which remains energized until the release of the connexion. When the subscriber N25 hangs up his receiver, the relay A energizes relay D2' which energizes the release magnet M.