Time delay circuit

Claim 1

A TIME DELAY CIRCUIT FOR CONTROLLING THE ENERGIZATION OF AN ELECTRIC DEVICE IN RESPONSE TO DIRECT CURRENT CONTROL VOLTAGES WHICH ARE APPLIED FROM POWER SUPPLY MEANS TO THE TIME DELAY CIRCUIT FOR VARYING LENGTHS OF TIME COMPRISING A PAIR OF CIRCUIT TERMINALS ADAPTED TO HAVE SAID CONTROL VOLTAGES APPLIED THEREACROSS, A NORMALLY NON-CONDUCTIVE SILICON CONTROLLED RECTIFIER HAVING ANODE, CATHODE AND GATE ELECTRODES, MEANS COUPLING SAID ELECTRIC DEVICE IN SERIES RELATION WITH SAID ANODE AND CATHODE ELECTRODES BETWEEN SAID PAIR OF TERMINALS TO EFFECT ENERGIZATION OF SAID ELECTRIC DEVICE WHEN SAID RECTIFIER IS FIRED INTO CONDUCTION, A TIME CONSTANT CIRCUIT INCLUDING RESISTANCE MEANS AND CAPACITANCE MEANS CONNECTED IN SERIES RELATION WITH EACH OTHER BETWEEN SAID TERMINALS WHEREBY SAID CAPACITANCE MEANS IN CHARGED THROUGH SAID RESISTANCE MEANS IN RESPONSE TO THE APPLICATION OF SAID CONTROL VOLTAGES TO SAID TERMINALS, DISCHARGE CIRCUIT MEANS FOR SAID CAPACITANCE MEANS INCLUDING A UNIJUNCTION TRANSISTOR HAVING AN EMITTER ELECTRODE AND A PAIR OF BASE ELECTRODES, MEANS COUPLING SAID EMITTER ELECTRODE TO ONE SIDE OF SAID CAPACITANCE MEANS, IMPEDANCE MEANS CONNECTED BETWEEN ONE OF SAID BASE ELECTRODES AND THE OTHER SIDE OF SAID CAPACITANCE MEANS, AND CIRCUIT MEANS COUPLED TO SAID SUPPLY MEANS FOR PROVIDING A VOLTAGE ACROSS SAID BASE ELECTRODES TO NORMALLY MAINTAIN SAID UNIJUNCTION TRANSISTOR NON-CONDUCTIVE, SAID UNIJUNCTION TRANSISTOR BEING FIRED INTO CONDUCTION TO DISCHARGE SAID CAPACITANCE MEANS THROUGH SAID IMPEDANCE MEANS WHEN SAID CAPACITANCE MEANS IS CHARGED TO A PREDETERMINED VOLTAGE VALUE, MEANS COUPLING SAID GATE AND CATHODE ELECTRODES TO SAID IMPEDANCE MEANS TO EFFECT FIRING OF SAID RECTIFIER IN RESPONSE TO THE DISCHARGE OF SAID CAPACITANCE MEANS THROUGH SAID INPEDANCE MEANS, AND OTHER DISCHARGE CIRCUIT MEANS PROVIDING A PREDETERMINED RATE OF DISCHARGE FOR SAID CAPACITANCE MEANS UPON THE CESSATION OF A CONTROL VOLTAGE APPLIED TO SAID TIME DELAY CIRCUIT FOR A TIME LESS THAN THAT REQUIRED TO CHARGE SAID CAPACITANCE MEANS TO SAID PREDETERMINED VALUE, SAID OTHER DISCHARGE CIRCUIT MEANS INCLUDING ONE-WAY VALVE MEANS CONNECTED IN PARALLEL CIRCUIT RELATION WITH SAID RESISTANCE MEANS AND IN SERIES RELATION WITH SAID CAPACITANCE MEANS BETWEEN SAID TERMINALS, AND OTHER RESISTANCE MEANS CONNECTED IN PARALLEL CIRCUIT RELATION WITH SAID TIME CONSTANT CIRCUIT.