| 摘要 |
1,185,296. Automatic exchange systems. SIEMENS A.G. 19 Aug., 1968 [21 Aug., 1967], No. 39558/68. Heading H4K. An electric circuit arrangement for a telephone system includes a current responsive device, such as a relay, in series with a rectifier and an inductive device connected across said current responsive device and rectifier so that when a D.C. supply is connected to the circuit current flows in the inductive device and when the supply is broken a self-induced voltage derived from the inductive device renders the rectifier conductive and the current responsive device is operated. The figure shows speech wires 1, 2 with relay contacts lha, lhb, 2ka, 2kb of a multi-stage switching arrangement therein. When a source U is connected to wires 1, 2 current flows through the closed contacts, rectifiers 11, 21 and inductors L1, L2, but the coils RKA and RKB of the relays controlling the contacts are not energized. When the connection of the voltage source U is broken the induced voltages of the inductor terminals energize relay coils RKA and RKB to open the contacts. |
