Abstract A stable electronic trigger circuit having a predetermined DC hysteresis in the operation of the circuit is formed as an integrated circuit including three NPN transistors: an input transistor and a pair of output transistors connected in a Darlington amplifier configuration directly driven from the collector of the input transistor. Operating potential for the trigger circuit is obtained from the voltage drop across a string of series connected transistor diodes, and the input transistor has collector and emitter resistors connected to it, with the collector resistor having an impedance many times that of the emitter resistor. The switching levels of the trigger circuit are determined by the ratio of the collector and emitter resistors in the input transistor circuit and/or by the base-emitter voltage drops across the transistors.
The combination according to claim 1 wherein all of the transistors are NPN transistors and wherein the transistors, and the collector and emitter resistors all are formed in a single integrated circuit.
Claim 2
Dependent Claim
24 words
The combination according to claim 1 wherein the plurality of output transistors include first and second output transistors interconnected as a Darlington amplifier pair.
Claim 3
Dependent Claim
19 words
The combination according to claim 1 wherein the regulated direct current operating potential is a predetermined constant operating potential.
Claim 4
Dependent Claim
27 words
The combination according to claim 4 wherein the predetermined constant operating potential is obtained from the voltage drop across a predetermined number of series-connected, forward-biased semiconductor diodes.
Claim 5
Dependent Claim
37 words
The combination according to claim 5 wherein the plurality of output transistors includes first and second output transistors interconnected as a Darlington amplifier pair and the predetermined number of semiconductor diodes is three series-connected, forward-biased semiconductor diodes.