Control circuits employing unijunction transistors for firing controlled rectifiers

Claim 1

A CONTROL CIRCUIT COMPRISING A FIRST AND SECOND INPUT LEAD FOR CONNECTION IN CIRCUIT WITH A SUPPLY HAVING A PREDETERMINED VOLTAGE, A UNIJUNCTION TRANSISTOR HAVING A BASE-ONE, A BASE-TWO AND EMITTER ELECTRODES, A CAPACITOR CONNECTED IN CIRCUIT WITH SAID EMITTER ELECTRODE AND SAID BASE-ONE ELECTRODE, A FIRST RESISTIVE MEANS CONNECTED IN CIRCUIT WITH SAID FIRST INPUT LEAD AND SAID BASE-TWO ELECTRODE OF SAID UNIJUNCTION TRANSISTOR, A SECOND RESISTIVE MEANS, A ZENER DIODE HAVING A CATHODE AND AN ANODE, SAID ZENER DIODE HAVING A PREDETERMINED BREAKDOWN VOLTAGE, CIRCUIT MEANS CONNECTING SAID SECOND RESISTIVE MEANS AND SAID ZENER DIODE IN CIRCUIT WITH SAID FIRST RESISTIVE MEANS AND SAID SECOND INPUT LEAD SO THAT SAID FIRST AND SECOND RESISTIVE MEANS PROVIDE A VOLTAGE DIVIDER ACTION THEREBY CAUSING THE INTERBASE VOLTAGE OF SAID UNIJUNCTION TRANSISTOR TO BE SUBSTANTIALLY EQUAL TO THE BREAKDOWN VOLTAGE OF SAID ZENER DIODE AND A FRACTIONAL PART OF THE SUPPLY VOLTAGE, A THIRD RESISTIVE MEANS, SAID SECOND AND THIRD RESISTIVE MEANS BEING CONNECTED IN CIRCUIT WITH THE CATHODE OF SAID ZENER DIODE, SAID THIRD RESISTIVE MEANS AND SAID CAPACITOR BEING SERIALLY CONNECTED ACROSS SAID ZENER DIODE, SAID VOLTAGE DIVIDER ACTION OF SAID FIRST AND SECOND RESISTORS COMPENSATING FOR VARIATIONS IN THE SUPPLY VOLTAGE BY VARYING THE INTERBASE VOLTAGE OF THE UNIJUNCTION TRANSISTOR.