Abstract: An apparatus for operating a fluorescent lamp having first and second power source circuits, the second power source circuit including a high frequency transformer having two or more outputs for supplying pre-heating electric currents to filaments, the second power source circuit being arranged to be controllable individually from the first power source circuit for supplying a tube electric current to turn on a fluorescent lamp so that the electric power level for pre-heating the filaments is switched between a state where a light adjustment is performed by turning on/off a tube electric current at high frequency and a state where the fluorescent lamp is turned off in a standby mode.

Abstract: In a multi-output power supply apparatus including a primary winding and a plurality of secondary windings, the switching operation of the primary winding is controlled in accordance with the output of one of the secondary windings. The switching operation of a switching device for switching the output of another secondary winding is synchronized with the switching operation of the primary winding, or is controlled in accordance with an input voltage for the primary winding.