Voltage suppression circuit for a DC-to-DC voltage converter circuit

In a voltage conversion circuit, comprising a source of input DC voltage, an input voltage switching circuit and a transformer having a primary winding coupled in series with the switching circuit and input DC voltage for periodically receiving DC voltage thereat and having a secondary winding connected to a DC output circuit for producing a DC output voltage of a given polarity, the transformer primary normally undesirably produces a switching circuit damaging voltage spike of a polarity opposite the given polarity upon the voltage being removed from the transformer primary by the switching circuit. A voltage suppression circuit is responsive to the voltage polarity reversal in the transformer primary, which occurs when the input voltage is removed therefrom for storing the energy which would otherwise produce the voltage spike. In response to the switching circuit thereafter applying the DC input voltage to the transformer primary, the stored energy is then connected to the DC output circuit to add energy thereto.