Abstract: A DC-to-AC voltage converter having galvanically separate onput and output circuits, and comprising a converter transformer having at least one primary winding; a resonance capacitor connected to said at least one primary winding; a switching transistor, of which the collector-emitter path is series-connected to the at least one primary winding; and drive means for the switching transistor, wherein charge storage in the base-collector area of the switching transistor provides base drive for the switching transistor, and further comprising control means for detecting an increase of the collector-emitter voltage (Uce) of the switching transistor and for providing in response to such an increase and at least in a period of time directly following the increase, an additional base drive current for the switching transistor, which additional base drive current is gradually increased at a predetermined rate in such a manner that the storage time of the switching transistor remains substantially constant over the ope

Abstract: A high frequency power circuit for energizing at least one gas discharge lamp with two filaments. The circuit is adapted to be supplied with power from a DC voltage source, and comprises semiconductor switching elements and control means for the semiconductor switching elements. The circuit also comprises a high frequency transformer having at least one primary winding which, in operation, is supplied with an AC voltage signal by the semiconductor switching elements. The transformer has at least one secondary main winding and secondary auxiliary windings. The secondary auxiliary windings, in operation, energize the filaments of the at least one gas discharge lamp. The control means are adapted to disconnect, in a stand-by mode, by at least one controllable switching means. The connection between the at least one secondary main winding and the at least one gas discharge lamp.

Abstract: A safety transformer with low coupling factor, which comprises at least one primary winding mounted on a spool and at least one secondary winding mounted on a spool, and a core including a first section cooperating with the primary winding(s) and a second section cooperating with the secondary winding(s). The first and second core sections have facing ends and all facing ends of these core sections are separated by an isolating means.

Abstract: A DC-to-AC voltage converter for the supply of power to at least one load, comprising an input circuit and at least one output circuit galvanically separated from said input circuit, and a converter transformer. According to the invention a primary winding of the converter transformer is series-connected to a switching transistor, which series circuit arrangement is connected between a positive input terminal and a negative input terminal, with one or more resonance capacitors being connected in parallel with the collector-emitter circuit of the switching transistor and/or in parallel with said primary winding.