Abstract: An apparatus for operating discharge lamp. The apparatus includes a source of electrical power, switching devices for switching the electrical power, a control circuit for controlling the switching devices, a transformer having a primary winding for receiving the electrical power switched by the switching devices and a secondary winding for supplying power to the lighting apparatus, a resonant circuit including an inductor and a capacitor for regulating the frequency of the electrical power and a circuit for powering the control circuit, the powering circuit including a secondary winding on the inductor and an additional winding on the transformer connected in a differential manner.

Abstract: The invention circuit for a discharge lamp comprising a first switching circuit, a series resonant circuit, and a current transformer. The series resonant circuit energizes the discharge lamp by means of resonant output corresponding to the output from the first switching circuit. The current transformer incorporates the first, second, and the third windings. When the first winding inserted in the series resonant circuit is driven, the first winding outputs a predetermined amount of current to the second and third windings. The inverter circuit further comprises a second switching circuit, a pair of time constant circuits, and a control circuit. The second switching circuit controls ON-OFF operation of the first switching circuit in response to the output from the second winding.

Abstract: An inverter includes a DC voltage source for supplying a DC voltage. A switching transistor switches the DC voltage supplied from the DC voltage source. A parallel resonant circuit receives the DC voltage switched by the switching transistor and generates an AC output. A self-excited oscillator includes a detector for detecting at least part of the AC output from the resonant circuit for supplying the detection output between the base and emitter of the switching transistor so as to control the ON and OFF of the switching transistor and supplying a base current to the switching transistor. A variable impedance element includes a series circuit comprised of a variable resistance element and a capacitor for changing the resistance value of the variable resistance element, thereby to change the combined impedance value to change the ON period of the switching transistor.