Abstract: A frequency-modulated converter with a series-parallel resonance, particularly for driving any ohmic or inductive load, including gas discharge tubes, wherein a commutating voltage switch in the form of a transistor is provided and is connected in series between a negative electrode of a direct current voltage source and a first terminal of an inductor, and a pulse generator circuit is provided between the voltage source and the transistor's control electrode and the inductor's second terminal is connected to the primary winding of a transformer. A first capacitor and rectifier diode are also provided in a first and second parallel branch respectively between the transistor's charge receiving and charge emitting electrodes, and a second capacitor is provided across the voltage source's electrodes, and a smoothing capacitance is provided for the voltage source, the second capacitor being connected in series with the inductor via the diode.