Abstract: In order to increase the resonance frequency of a transformer, the secondary winding is divided into several (identical) coils, which are each connected to a corresponding individual bridge rectifier circuit. The outputs of the bridge rectifier circuits are connected in series and each coil is wound in a sense opposite to that of the immediately adjacent coil(s). Each coil is divided into two series-connected sections which are each wound in a corresponding individual winding compartment of the coil former. The series connection between the two coil sections extends through a passage at the bottom of the partition wall between the two winding compartments. Consequently, the coil ends are located on the outerside of each coil section so that it is possible to provide a simple connection with short connecting leads.