Abstract: A power supplying section has a signal transmitting secondary coil which is not inductively coupled to a power transmitting primary coil, and actuates as a feedback coil of a switching element. A load section has a power transmitting secondary coil arranged so as to be confronted with the power transmitting primary coil when the load section is attached to the power supplying section, and also has a signal transmitting primary coil so as to be confronted with the signal transmitting secondary coil when the load section is attached to the power supplying section. When the load section is not attached to the power supplying section, the voltage is not induced in the signal transmitting secondary coil as the feedback coil, and the switching of the switching element is intermittently carried out.

Abstract: An inverter power supply operating at a high efficiency to provide an AC voltage to a load. The power source includes a DC voltage source and an output transformer with a primary winding, secondary winding, and a feedback winding. An FET is connected in series with the primary winding across the DC voltage source. The primary winding is connected to a capacitor to form a L-C resonant circuit which, in response to the switching of FET, provides across the primary winding an oscillation voltage to be applied through the secondary winding to drive a load, while inducing a feedback voltage across the feedback winding. The oscillation voltage is allowed to go negative at a point between FET and the primary winding. A biasing capacitor is connected to apply an offset voltage which is additive to the feedback voltage so as to give a bias voltage to FET.