Regulated power supply with plural outputs for tube filaments and transistors

Claim 1

A POWER SUPPLY CIRCUIT ADAPTED TO BE ENERGIZED FROM A SUPPLY VOLTAGE WHICH VARIES FOR CONTROLLING THE CURRENT APPLIED TO A HEATING ELEMENT WHICH HAS A RESISTANCE WHICH INCREASES WITH TEMPERATURE, SAID CIRCUIT INCLUDING IN COMBINATION, RESISTOR MEANS CONNECTING THE HEATING ELEMENT TO THE SUPPLY VOLTAGE FOR REDUCING THE VOLTAGE APPLIED THERETO, A SCHMITT TRIGGER CIRCUIT INCLUDING FIRST AND SECOND TRANSISTORS, SAID FIRST TRANSISTOR BEING NORMALLY NONCONDUCTIVE AND HAVING A CONTROL ELECTRODE AND OUTPUT ELECTRODES CONNECTED ACROSS SAID RESISTOR MEANS FOR SELECTIVELY SHORTING THE SAME, SAID SECOND TRANSISTOR HAVING A CONTROL ELECTRODE COUPLED TO THE HEATING ELEMENT AND OUTPUT ELECTRODES COUPLED TO SAID CONTROL ELECTRODE OF SAID FIRST TRANSISTOR AND OPERATIVE WHEN THE VOLTAGE ACROSS AT LEAST A PORTION OF SAID HEATING ELEMENT REACHES A PREDETERMINED VALUE TO CAUSE CONDUCTION OF SAID FIRST TRANSISTOR AND THEREBY INCREASE THE VOLTAGE APPLIED TO THE HEATING ELEMENT, WHEREBY THE CURRENT THROUGH THE HEATING ELEMENT IS REDUCED BY ACTION OF SAID RESISTOR MEANS AND HEATING OF THE HEATING ELEMENT INCREASES THE RESISTANCE THEREOF AND THE VOLTAGE THEREACROSS TO CAUSE OPERATION OF SAID SCHMITT TRIGGER CIRCUIT TO SHORT SAID RESISTOR MEANS AND INCREASE THE VOLTAGE APPLIED TO THE HEATING ELEMENT.