Abstract: A resonance controlled conductive heating apparatus for heating a conductive load, has input terminals for receiving AC power. The primary winding of a transformer is coupled to the input terminals. First and second electrodes are coupled to the secondary winding of the transformer and are adapted respectively to electrically engage the conductive load in first and second contact points spaced from each other for direct passage of current therebetween. A resonant circuit is coupled between the secondary winding of the transformer and the electrodes. The resonant circuit has inductance, capacitance, voltage and operating frequency properties set to control a maximum current flowing across the conductive load between the electrodes.

Abstract: The resonant switching power supply circuit comprises positive and negative DC input terminals. First and second switching elements are connected in series between the DC input terminals. Each switching element has a control input for receiving a control signal controlling a duty cycle of the switching element. A first capacitor is connected between the DC input terminals. Second and third capacitors are connected in series between the DC input terminals. A first pair of reverse biased rectifying elements in series is connected between the DC input terminals. Each rectifying element of the first pair is connected in parallel with a respective one of the switch elements. A second pair of reverse biased rectifying elements in series is connected between the DC input terminals. Each rectifying element of the second pair is connected in parallel with a respective one of the second and third capacitors.