Abstract: A capacitive stud welding having an inductive-capacitive welding current supply circuit is provided with a stud and a tunable inductor. The stud is attachable to a workpiece and has an end portion shaped to retain in place on the workpiece at the weld point the flux from the stud to form an optimum weld. The tunable electrical inductor optimizes resonance of the inductive-capacitive welding current supply circuit and the flow of welding current through the stud and workpiece.

Abstract: The present invention is a driving circuit that comprises a magnetically permeable core, a high voltage secondary winding around the core with the secondary winding being connectable to a device to be powered, a circuit connectable to a D.C. power source and being magnetically coupled to the secondary winding to induce a voltage thereacross sufficient to power a device, a plurality cf connected windings wound around the core, a RC network and a plurality of parallel connected transistors coupled to the windings and the RC network with each respective transistor having a base terminal connected to the RC network by a respective current-variable resistive element, and a first primary winding connected in series with a plurality of second primary windings, and each primary winding connected in parallel with a respective capacitor.

Abstract: A lamp driver circuit includes a high voltage secondary winding connectable to a gas discharge lamp. The secondary is wound on a magnetic core together with a pair of primary windings. The primary windings are coupled to one another as well as to an R-C network and an amplifier stage, the latter of which comprises a plurality of fast-switching transistors connected in parallel with one another. The bases of each of the transistors are connected to the R-C network by way of an element such as an incandescent lamp filament whose resistance varies with the current through the element.