Abstract: A circuit arrangement for a DC to DC converter has at least one switching transistor and one transformer. The transformer includes a primary winding which is connected in the collector circuit of the transistor and a secondary winding from which at least one stabilized DC voltage may be tapped by way of rectifiers. The switching transistor is actuated and blocked by way of a control component in dependence upon load. A voltage comparison device is provided for comparing the collector-emitted voltage of the switching transistor with a predetermined reference value, and upon overshoot of the reference voltage the collector-emitter voltage is analyzed for disconnection of the base current of the switching transistor.