Power supplying apparatus and method

摘要

A primary winding T1 and a switching circuit 1 are serially inserted between input terminals Ti1 and Ti2 to which an alternating current is supplied. A diode 2, a resistor 3, and a capacitor 4 are serially inserted in parallel with the primary winding T1. A detecting circuit 5 is connected to both ends of the capacitor 4 and to an emitter and a collector of a phototransistor 7b. A control circuit 6 controls the switching circuit 1. A diode bridge 8 and a capacitor 9 are provided for a secondary winding T2. Output terminals To1 and To2 are connected to both ends of the capacitor 9. A voltage detecting circuit 10 is provided in parallel with the capacitor 9. The voltage detecting circuit 10 detects voltages which are outputted from the output terminals To1 and To2 and supplies the detected voltages to a control circuit 11. The control circuit 11 controls a light emitting diode 7a.