Phase control circuits for light activated switches using a variable resistor with an a. c. voltage across it as the phase control

Claim 1

A PHASE CONTROL CIRCUIT FOR A LIGHT ACTIVATED SWITCH INCLUDING A PAIR OF SUPPLY TERMINALS FOR CONNECTION TO A SOURCE OF PULSATING VOLTAGE, A LIGHT ACTIVATED SWITCH HAVING AN ANODE AND A CATHODE TERMINAL, SAID ANODE AND CATHODE TERMINALS BEING COUPLED TO SAID SUPPLY TERMINASL WHEREBY SAID LIGHT ACTIVATED SWITCH IS ENERGIZED BY THE SAID PULSATING VOLTAGE SOURCE, SAID LIGHT ACTIVATED SWITCH HAVING A THRESHOLD RADIATION LEVEL FOR FIRING AND A LOW RESISTANCE WHEN FIRED THEREBY PRESENTING ESSENTIALLY A SHORT CIRCUIT BETWEEN SAID SUPPLY TERMINALS WHEN FIRED, A SOURCE OF RADIATION LOCATED TO IRRADIATE SAID LIGHT ACTIVATED SWITCH, SAID SOURCE OF RADIATION BEING COUPLED TO SAID SUPPLY TERMINALS WHEREBY SAID SOURCE OF RADIATION IS ENERGIZED BY THE SAID PULSATING VOLTAGE SOURCE AND DE-ENERGIZED BY SAID LIGHT ACTIVATED SWITCH IS FIRED, CONTROL MEANS CONNECTED IN CIRCUIT RELATION WITH SAID SOURCE OF RADIATION AND CONTROLLING THE MAGNITUDE OF THE VOLTAGE APPLIED TO SAID SOURCE OF RADIATION THEREBY CONTROLLING THE INTENSITY OF SAID SOURCE OF RADIATION AND PROVIDING PHASE CONTROL FIRING OF SAID LIGHT ACTIVATED SWITCH.