Inverter unit with automatic output interruption upon associated equipment failure

Claim 1

TRANSISTOR OSCILLATOR UNIT FOR CONVERTING A D.C. VOLTAGE INTO AN A.C. VOLTAGE, COMPRISING, IN COMBINATION, A PAIR OF TRANSISTORS CONNECTED IN PUSH-PULL RELATION, A TRANSFORMER WITH A PLURALITY OF PRIMARY WINDINGS AND A SECONDARY WINDING CONNECTED TO A LOAD CIRCUIT, THE COLLECTORS OF SAID PAIR OF TRANSISTORS BEING CONNECTED TO THE ENDS OF A FIRST PRIMARY WINDING AND THE BASE ELECTRODES OF SAID PAIR OF TRANSISTORS TO THE ENDS OF A SECOND PRIMARY WINDING OF SAID TRANSFORMER, EACH OF SAID PRIMARY WINDINGS BEING PROVIDED WITH A CENTER TAP, A TIME CONSTANT MEMBER CONNECTED BETWEEN THE CENTER TAPS OF SAID FIRST AND SAID SECOND PRIMARY WINDING, A D.C. VOLTAGE SOURCE BEING CONNECTED BETWEEN THE CENTER TAP OF THE FIRST PRIMARY WINDING AND THE EMITTERS OF SAID PAIR OF TRANSISTORS, AN AUXILIARY SWITCHING TRANSISTOR OF OPPOSITE CONDUCTIVITY TYPE BEING CONNECTED IN SERIES WITH SAID TIME CONSTANT MEMBER, WITH ITS EMITTER CONNECTED TO THE CENTER TAP OF SAID FIRST PRIMARY WINDING AND WITH ITS COLLECTOR TO THE CENTER TAP OF SAID SECOND PRIMARY WINDING, A POWER SUPPLY SOURCE DELIVERING A SWITCHING VOLTAGE INDEPENDENT OF SAID LOAD CIRCUIT, SAID POWER SUPPLY SOURCE BEING CONNECTED TO A PROTECTING CIRCUIT SERVING TO PUT A MEMBER OF SAID LOAD CIRCUIT IN AN INOPERATIVE STATE IN CASE OF EMERGENCY, SAID POWER SUPPLY SOURCE BEING COUPLED TO THE BASE-EMITTER CIRCUIT OF SAID AUXILIARY TRANSISTOR, SO THAT UNDER NORMAL OPERATING CONDITIONS SAID AUXILIARY TRANSISTOR IS DRIVEN CONDUCTIVELY, BUT IN CASE OF A FAILURE OF SAID SWITCHING VOLTAGE SAID AUXILIARY TRANSISTOR IS BLOCKED AND THEREBY THE OSCILLATION INTERRUPTED.