Dc series voltage regulator with gating means for output to remain off

Abstract

A series voltage regulator for producing a regulated direct output voltage from a direct input voltage that is subject to variations, such as gradually increasing with time upon application of source voltage, with first and second transistors of opposite polarity where the collector emitter path of the first transistor is in series relation between the input and output terminals and the emitter-collector path of the second transistor is in series relation between the input terminal and the base electrode of the first transistor. A voltage limiter such as a zener diode is connected between the base of the second transistor and a common input-output terminal. As source voltage increases from zero, the first transistor remains off until it is supplied base drive, which occurs only after the second transistor becomes conductive. The second transistor will conduct when the input voltage exceeds the sum of the second transistor's base emitter voltage drop and the voltage drop of the zener diode. Saturation of the second transistor will cause the regulator to produce a steady output equal to the sum of the voltage drops of the zener diode and the base collector junction of the second transistor, minus the voltage drop of the base emitter junction of the first transistor.