Electronic control circuit

Claim 1

IN COMBINATION, A POWER TRANSISTOR HAVING A CONTROL TERMINAL, A LOAD TERMINAL, AND A COMMON TERMINAL, A FIRST SOURCE OF CURRENT HAVING FIRST AND SECOND TERMINALS, A LOAD IMPEDANCE CONNECTED IN SERIES WITH THE TERMINALS OF SAID SOURCE AND SAID LOAD AND COMMON TERMINALS, A GATE TURNOFF SWITCH HAVING AN ANODE, A CATHODE AND A FIRE GATE, A SECOND SOURCE OF CURRENT HAVING FIRST AND SECOND TERMINALS AT FIRST AND SECOND POTENTIALS WITH RESPECT TO THE POTENTIAL OF THE FIRST TERMINAL OF SAID FIRST SOURCE, A FIRST RESISTOR HAVING A FIRST TERMINAL CONNECTED TO ONE TERMINAL OF SAID SECOND SOURCE AND A SECOND TERMINAL, A SECOND RESISTOR HAVING A FIRST TERMINAL CONNECTED TO THE OTHER TERMINAL OF SAID SECOND SOURCE AND SECOND TERMINAL, THE ANODE AND CATHODE OF SAID GATE TURNOFF SWITCH BEING CONNECTED IN SERIES WITH THE SECOND TERMINALS OF SAID RESISTORS WHEREBY THE SECOND TERMINAL OF SAID SECOND RESISTOR IS AT A FIRST POTENTIAL OR A SECOND POTENTIAL WITH RESPECT TO THE FIRST TERMINAL OF SAID FIRST SOURCE ACCORDING AS CURRENT IS OR IS NOT FLOWING IN THE ANODE TO CATHODE PATH OF SAID GATE TURNOFF SWITCH, AN ELECTRICAL CONNECTION BETWEEN THE SECOND TERMINAL OF SAID SECOND RESISTOR AND THE CONTROL TERMINAL OF SAID POWER TRANSISTOR, THE POTENTIALS OF SAID SECOND SOURCE BEING SELECTED TO CAUSE THE POWER TRANSISTOR TO CONDUCT OR BE CUT OFF ACCORDING AS CURRENT IS OR IS NOT FLOWING BETWEEN THE ANODE AND CATHODE OF SAID GATE TURNOFF SWITCH, RESPECTIVELY, A THIRD RESISTOR AND A CAPACITOR CONNECTED IN SERIES ACROSS SAID FIRST RESISTOR, A UNIJUCTION TRANSISTOR HAVING AN EMITTER, A FIRST BASE AND A SECOND BASE, SAID EMITTER AND ONE OF SAID BASES BEING CONNECTED ACROSS SAID CAPACITOR, THE OTHER BASE BEING CONNECTED TO THE FIRE GATE OF SAD GATE TURNOFF SWITCH, AND SWITCHING MEANS OPERABLE IN RESPONSE TO AN APPLIED PULSE FOR APPLYING CURRENT TO THE FIRE GATE OF SAID GATE TURNOFF SWITCH TO CAUSE AVALANCHE CURRENT TO FLOW IN ITS ANODE TO CATHODE PATH TO TURN ON SAID POWER TRANSISTOR AND PRODUCE A VOLTAGE DROP ACROSS SAID FIRST RESISTOR, SAID UNIJUNCTION TRANSISTOR BEING CAUSED TO CONDUCT A PREDETERMINED TIME LATER BY THE CHARGE ACCUMULATING ON SAID CAPACITOR, SAID UNIJUNCTION TRANSISTOR BEING POLED TO APPLY A CUTOFF FLOW OF CURRENT TO THE FIRE GATE OF SAID GATE TURNOFF SWITCH TO CUT OFF CURRENT IN THE ANODE TO CATHODE PATH.