Relay circuit with chattering make contact - has electronic contact operated by optical coupler in parallel with relay contact

摘要

A winding in the circuit can be connected to a control d.c. voltage. An electronic contact is operated by at least one optical coupler (7). It is connected in parallel with the relay make contact. A light emitting diode (7) in the optical coupler lies in the relay control circuit. The electronic contact is conducting only at voltages above a specified threshold higher by an order of magnitude than the voltage across the current carrying contact. The apparatus has four terminals (1, 2, 3, 4). The photocell (72) in the optical couples is connected to the base of a Darlington pair (51).