Abstract: A control circuit for a flyback stepcharger comprising a source producing a urrent proportional to a power supply output in order to charge a capacitor. When the capacitor reaches a predetermined level the charging stops and switching transistors to the primary of the transformer of the stepcharger are turned on. When the primary current reaches another predetermined level the switching transistors are turned off. The source charging the capacitor is restarted a set time after the switching transistors are turned on. The stepcharging is terminated when the DC voltage of the power supply output reaches its set value as measured when the switching transistors are on.