to a rectifying circuit 2 and then rectified the rectified output signal from the rectifying circuit 2 is supplied to a series connection of capacitors 11 and 12 the series connection or path between transistors 21 and 22 is connected in parallel to the series connection of the capacitors 11 and 12 windings 31 and 32 of an oscillation transformer 30 are connected between the base and emitter electrodes of the transistors 21 and 22 respectively the emitter electrode of the transistor 21 and the collector electrode of the transistor 22 are connected together through a winding 33 of the oscillation transformer 30 for feeding back a current and through an input winding or primary winding 41 of a power source transfomer 40 to the connection point between the capacitors 11 and 12 a feedback winding 43 of the transformer 40 is connected through a resistor 3 to a winding 34 of the transformer 30 for voltage feedback and an output winding or secondary winding 42 of the transformer 40 is connected to a rectifying circuit 4 which is connected with a smoothing circuit 5 from which dc output terminals 6 are derived with the prior art transistor inverter shown in fig1 when the transistors 21 and 22 are made on and off alternately an alternating current appears at the input winding 41 of the transformer 40 as a result a desired dc voltage can be delivered to the output terminals 6 at this time since the ac current flowing through.