Abstract: Presented is an electronic circuit composed of various cooperating semiconductor-type devices controlling the degree and timing of triggering of a power switching device to effect controlled electrical conduction through the device. The circuit achieves a "zero-voltage-switch" (ZVS) function where the triggering of the power switching device can occur only during an interval when the main power terminal voltage is less than a predetermined value. The circuit comprises a high-voltage current limiting resistor comprised of a depletion MOSFET or JFET device used as a current limited source to drive other transistor amplifiers and switching circuits, the means of diverting this limited current through application of an external control signal separate from the power terminals, and a means of providing a limited source voltage to the external control means for use if required.