a voltage converter circuit for providing electrical energy to a capacitive load , the converter circuit having a pulse transformer having primary and secondary circuits . pulse signals are provided in the primary circuit by thyristor devices . the thyristors are quenched by circuitry contained in the secondary circuit , comprising a storage capacitor which conducts a quenching current through a bank of power transistors to at least a portion of a secondary winding . a magnetizing current from a further secondary winding in the secondary circuit is utilized to charge the capacitor .