Abstract: A series coupled component partially includes a) a load circuit including an inductor and an EL or EL array having capacitive load characteristic, b) a load circuit including an inductor, a bipolar capacitor, and a diode circuit adapted to supply bidirectional current flows across an LED or LD, or c) a load circuit including an inductor, an EL or EL array having capacitive load characteristic, and the diode circuit. An inverter has coupling output terminals coupled to one end or both ends of the load circuit whereby an AC power inverted from a DC power source is supplied to the load circuit to operate at least one member of the EL, EL array, LED and LD. The inverter has a pair of positive and negative switches each comprising a zero-crossing switch mechanism adapted to automatically close its channel when the current becomes zero, the pair of positive and negative switches each being provided with a bypass channel having a reverse current bypass diode for bypassing the zero-crossing switch mechanism.