Temperature sensing and control system

Claim 1

A TEMPERATURE SENSING AND CONTROL SYSTEM INCLUDING: AN ALTERNATING CURRENT SOURCE, MEANS FOR RECTIFYING THE ALTERNATING CURRENT INTO DIRECT CURRENT, SAID RECTIFYING MEANS COUPLED TO SAID SOURCE, A FREE RUNNING MULTI-VIBRATOR INCLUDING AT LEAST A UNIJUNCTION TRANSISTOR AND DRIVEN BY SAID DIRECT CURRENT FOR PROVIDING A PULSED OUTPUT, A TEMPERAURE SENSISTIVE BALANCED BRIDGE CIRCUIT INCLUDING A THERMISTOR IN EACH OF TWO OPPOSING LEGS FOR SENSING TEMPERATURE, A VARIABLE RESISTOR IN THE THIRD LEGS FOR RESISTIVELY BALANCING SID BRIDGE CIRCUIT WHEN SAID THERMISTORS SENSE A PREDETERMINED TEMPERATURE AND A FIXED RESISTOR IN THE LEG OPPOSITE THE THIRD LEG. MEANS FOR COUPLING THE PULSED OUTPUT TO THE INPUT OF SAID BALANCED BRIDGE, MEANS FOR COUPLING THE OUTPUT OF SID BALANCED BRIDGE TO SAID UNIJUNCTION TRANSISTOR, MEANS FOR SENSING THE POTENTIAL DIFFERENCE ACROSS SAID BALANCED BRIDGE FOR PROVIDING A FIRST SIGNAL REPRESENTATIVE OF A CHANGE IN TEMPERATURE IN ON DIRECTION FROM SAID PREDETERMINED TEMPERATURE AND FOR PROVIDING A SECOND SIGNAL REPRESENTATIVE OF A CHANGE IN TEMPERATURE IN THE OTHER DIRECTION FROM A PREDETERMINED TEMPERATURE AND FOR PROVIDING A THIRD SIGNAL REPRESENTATIVE OF SAID PREDETERMINED TEMPERATURE, MEANS FOR AMPLIFYING SAID FIRST SIGNAL, MEANS COUPLED TO SAID AMPLIFIER MEANS FOR PROVIDING TWO IDENTICAL SIGNALS EACH PROPORTIONAL TO THE AMPLIFIED SIGNAL, A TEMPERATURE VARYING ELEMENT HAVING FIRST AND SECOND INPUTS, SAID FIRST INPUT COUPLED TO ONE OF THE SAID ALTERNATING CURRENT SOURCE, A PAIR OF PHASE SENSITIVE ELEMENTS COUPLED IN PARALLEL BACK-TO-BACK TO THE OTHER SIDE OF SAID SOURCE, MEANS FOR COUPLING ONE OF SAID TWO IDENTICAL SIGNALS TO ONE OF THE PHASE SENSITIVE ELEMENTS, MEANS FOR COUPLING THE OTHER OF SAID TWO IDENTICAL SIGNALS TO THE OTHER OF THE PHASE SENSITIVE ELEMENTS, SAID SECOND INPUT OF SAID TEMPERATURE VARYING ELEMENT COUPLED TO SAID PAIR OF PHASE SENSITIVE ELEMENTS FOR COMPLETING THE ALTERNATING CURRENT CIRCUIT FOR OPERATING SAID TEMPERTURE VARYING ELEMENTS THROUGH SAID PHASE SENSITIVE ELEMENTS.