Alternating current silicon controlled rectifier switch

Claim 1

A CIRCUIT FOR CONTROLLING WHETHER CURRENT FLOWS BETWEEN AN A.C. SOURCE AND A TEMPERATURE CHANGING DEVICE, COMPRISING: A PAIR OF OPPOSITELY-POLED SILICON CONTROLLED RECTIFIERS CONNECTED IN PARALLEL BETWEEN SAID SOURCE AND SAID DEVICE, EACH OF SAID SILICON CONTROLLED RECTIFIERS HAVING AN ANODE, A CATHODE, AND A CONTROL ELECTRODE; A VOLTAGE DIVIDER CONNECTED BETWEEN SAID ANODES, SAID VOLTAGE DIVIDER HAVING A MIDPOINT; MEANS, COMPRISING A PAIR OF SIMILARLY POLED DIODES FOR APPLYING THE POTENTIAL AT SAID MIDPOINT TO SAID CONTROL ELECTRODES OF SAID SILICON CONTROLLED RECTIFIERS; A CONNECTION COMPRISING A PAIR OF OPPOSITELY-POLED FRONT-TO-FRONT DIODES CONNECTED IN SERIES BETWEEN SAID ANODES, SAID CONNECTION HAVING A MIDPOINT; A TRANSISTOR HAVING ITS COLLECTOR-EMITTER CIRCUIT BETWEEN SAID MIDPOINT OF SAID VOLTAGE DIVIDER AND SAID MIDPOINT OF SAID CONNECTION; DISABLING MEANS, FOR APPLYING A D.C. POTENTIAL TO THE BASE ELECTRODE OF SAID TRANSISTOR, SAID MEANS COMPRISING; A METER WHEREIN THE POINTER CLOSES A CONTACT AND COMPLETES A CIRCUIT THROUGH A HOLDING COIL;