Firing angle control circuit for silicon controlled rectifiers

Claim 1

IN AN ALTERNATING CURRENT CIRCUIT INCLUDING A SILICON CONTROLLED RECTIFIER FOR INTERRUPTING FLOW OF CURRENT, A SOURCE OF DIRECT CURRENT SENSING VOLTAGE, AND A DIRECT CURRENT AMPLIFIER PROVIDING A TRIGGERING CURRENT OPERATING SAID SILICON CONTROLLED RECTIFIER, THE IMPROVEMENT COMPRISING: PHASE SHIFTING MEANS FOR PROVIDING A CURRENT ALPHA (A) DEGRESS OUT OF PHASE WITH SAID ALTERNATING CURRENT, HALF WAVE RECTIFIER MEANS CONNECTED TO SAID PHASE SHIFTING MEANS AND PROVIDING AN INHIBITING SIGNAL TO SAID DIRECT CURRENT AMPLIFIER, SAID INHIBITING SIGNAL BEING IMPOSED UPON SAID SENSING VOLTAGE TO LIMIT TRANSMISSION OF A TRIGGERING CURRENT TO SAID SILICON CONTROLLED RECTIFIER TO THAT PERIOD OF A GIVEN ALTERNATING CURRENT CYCLE IN WHICH THE VOLTAGE VARIES BETWEEN MINIMUM AND THAT OBTAINED AT ANGLE ALPHA (A); SAID PHASE SHIFTING MEANS INCLUDING A RESISTIVE-CAPACITIVE NETWORK.