Abstract: An electric energy conversion apparatus comprising a.d.c. - a.c. conversion unit with a first solid state controllable power switch arrangement and a second solid state controllable auxiliary switch arrangement. Said first and second switch arrangements have their respective outputs connected to the respective ends of a primary winding of a transformer for providing at its secondary winding an a.c. voltage derived by the recurrent on-off switching action of said first power switch arrangement from an input d.c. The switching action performed by said first power switch arrangement is controlled by a control circuit arrangement in such a manner that said first switch arrangement is always switched into its non-conductive state prior to saturation of the core material of said transformer, and is switched into its conductive state directly following the switching action causing said second switch arrangement to become non-conductive. With said d.c.-a.c.

Abstract: A power supply provides a low-level DC voltage to DC load circuits by first rectifying the standard AC voltage and thereafter reducing the rectified AC voltage to the low-level DC voltage. The reduction of the rectified AC voltage to the low-level DC voltage is accomplished by a power transformer which is switched on or off by a pair of switching transistors. The switching transistors are operated in a "push-pull" mode by a pair of control transformers operating in combination with a control circuit. The control circuit produces various pulse conditions in the control transformers which turn their respective switching transistors on and off in a prescribed manner.