GB898181A - Bi-stable control circuits for electromagnetic relays - Google Patents

Abstract

898,181. Transistor bi-stable circuits. ERICSSON TELEPHONES Ltd. March 29, 1961 [May 5, 1960], No. 15857/60. Class 40(6). A bistable control circuit for an electromagnetic relay having a coil of the relay connected into the load circuit of one or both of two switching elements includes a core of "square loop" material having two output windings, one end of each being connected to the control electrode of a separate switching element. The two windings 1, 11 of a polarised relay are connected into the collector circuits of transistors T1, T2 which forms a bi-stable trigger circuit to switch the current through either one or other of the windings. Triggering pulses are applied via diodes D1, D2 to the bases of the transistors from output windings on a square loop core when the state of the core is switched by any suitable means. The relay may be polarised as shown by a third winding or by a permanent magnet. A single winding relay, Fig. 2 (not shown), may be used, connected into the collector circuit of only one transistor. Valves may be used in place of transistors.