Abstract: A device for stabilizing the output of a DC-DC converter of the type wherein smoothed direct current is supplied to a load through a series combination of a switching element which is controlled by a train of pulses from a pulse oscillator and an inductor. An astable multivibrator and a differential amplifier are connected in parallel with a DC source. The switching element is controlled by a train of pulses from the astable multivibrator. The differential amplifier compares the smoothed output from a smoothing circuit with a reference voltage and the two outputs therefrom are applied to two time constant circuits of the astable multivibrator so as to control the relative variation between the discharge times thereof.