Abstract: Shunt regulation for a high-voltage circuit including a ferroresonant transformer has control circuitry associated with a low-voltage control winding on the transformer, the control winding being magnetically coupled with the high-voltage secondary winding thereof. The control circuitry includes a zener diode for clamping peak voltages on the control winding and a sub-circuit including a voltage-divider and a capacitor. An averaged voltage from the divider/capacitor is compared with a reference by a comparator. Both the comparator and the zener diode serve to turn on a transistor connected across the control winding output, thereby allowing current to flow through the control winding, dropping the output voltage thereof. Regulation of the output voltage on the transformer high-voltage secondary results.