Solid-state, all-transistorized power supplies are available in both medium frequency (2 to 10 kHz) and high frequency (150 to 400 kHz) with high output efficiencies that need no special cooling requirements. A single power supply can be built with both medium and high frequency capability. The power supplies have electronic auto load matching, so when part change occurs, the power supply adjusts automatically. There is no need for manual change of transformer taps or manual addition or reduction of capacitance. The power supplies can be equipped with multiple outputs to allow several heating operations (up to 7) to be run simultaneously at the rated kW of the power supply.