Protective circuitry for an ignitron firing circuit

Claim 1

IN A CIRCUIT FOR APPLYING SUCCESSIVE AT LEAST PARTIAL HALF-CYCLES OF ALTERNATING POLARITY TO A LOAD FROM A POWER SOURCE AND THROUGH A PAIR OF INVERSE PARALLEL CONNECTED IGNITRONS, EACH OF SAID IGNITRONS HAVING AN SCR CONNECTED BETWEEN THE ANODE AND THE IGNITOR THEREOF FOR CONTROLLING THE CONDUCTION THEREOF, PROTECTIVE CIRCUITRY COMPRISING IN COMBINATION: REVERSE TRANSIENT CONTROLLING MEANS CONNECTED BETWEEN THE ANODE OF EACH SAID SCR AND THE CATHODE OF ONE OF SAID SCR AND SAID IGNITRON CONTROLLED THEREBY, SAID REVERSE VOLTAGE CONTROLLING MEANS BEING OF A TYPE BLOCKING FORWARD CURRENT FLOW THERETHROUGH AND CAPABLE OF PASSING ONLY REVERSE VOLTAGES ABOVE A PREDETERMINED VOLTAGE LEVEL FOR PREVENTING APPLICATION OF SAID REVERSE TRANSIENT VOLTAGES ABOVE SAID VOLTAGE LEVEL ACROSS SAID SCR''S; CHARGEABLE MEANS AND MEANS CONNECTING SAID CHARGEABLE MEANS BETWEEN THE ANODES OF SAID SCR''S SO THAT EXCESSIVE FORWARD VOLTAGE TRANSIENTS APPEARING ON THE ANODES OF SAID SCR''S CHARGES SAID CHARGEABLE MEANS RATHER THAN CAUSING CONDUCTION THROUGH SAID SCR''S; WHEREBY SAID SCR''S ARE PROTECTED AGAINST EXCESSIVE REVERSE AND FORWARD VOLTAGE TRANSIENTS.