Smoke, flame, critical temperature and rate of temperature rise detector

Claim 1

AN ELECTRICAL CIRCUIT COMPRISING: A SOURCE OF REGULATED D.C. VOLTAGE; FIRST AND SECOND PHOTOCONDUCTIVE DEVICES CONNECTED IN SERIES ACROSS SAID SOURCE; A RESISTANCE LOWER THAN THE DARK RESISTANCE OF SAID FIRST PHOTOCONDUCTIVE DEVICE CONNECTED IN PARALLEL WITH SAID FIRST PHOTOCONDUCTIVE DEVICE; A GROUNDED EMITTER, TRANSISTORIZED DIFFERENTIAL AMPLIFIER ELECTRICALLY CONNECTED TO RECEIVE THE VOLTAGE ACROSS SAID SECOND PHOTOCONDUCTIVE DEVICE AS ONE INPUT THERETO; A THIRD PHOTOCONDUCTIVE DEVICE CONNECTED IN SERIES WITH A RESISTANCE ACROSS SAID SOURCE, THE VOLTAGE ACROSS SAID THIRD PHOTOCONDUCTIVE DEVICE BEING DIRECTED AS A SECOND INPUT TO SAID DIFFERENTIAL AMPLIFIER; MEANS FOR DIRECTING BEAMS OF LIGHT OF CONTROLLED INTENSITY UPON SAID SECOND AND SAID THIRD PHOTOCONDUCTIVE DEVICES; A CONTROL-RECTIFIER CONNECTED IN SERIES WITH AN INDICATING CIRCUIT ACROSS SAID SOURCE; A TRIGGER ELECTRODE EMBODIED BY SAID CONTROL RECTIFIER; MEANS FOR COUPLING THE ELECTRICAL OUTPUT OF SAID DIFFERENTIAL AMPLIFIER TO SAID TRIGGER ELECTRODE; CRITICAL TEMPERATURE RESPONSIVE SWITCHING MEANS; RATE OF RISE OF TEMPERATURE RESPONSIVE SWITCHING MEANS; AND MEANS CONNECTING SAID CRITICAL TEMPERATURE SWITCHING MEANS AND SAID RATE OF RISE OF TEMPERATURE SWITCHING MEANS BETWEEN SAID TRIGGER ELECTRODE AND A SOURCE OF ELECTRICAL ENERGY, WHEREBY CLOSING OF EITHER OF SAID SWITCHING MEANS WILL ENERGIZE SAID TRIGGER ELECTRODE TO RENDER SAID CONTROL RECTIFIER CONDUCTIVE.