| 摘要 |
<p>PURPOSE:To light up a low-voltage and high-power incandescent lamp, for example, a halogen lamp, at the stabilized voltage, using a commercial AC. CONSTITUTION:A commercial AC is full-wave rectified by a diode stack D1 and then is applied to a halogen lamp L1 through an inverter circuit 12 and a high-frequency transformer T1. The voltage of a secondary winding C of the high-frequency transformer T1 is detected by a detection circuit 14 and the collector current of a transistor Q3 is controlled by means of the output of an operating amplifier IC2. When the voltage across a capacitor C1 which is charged by the collector current of the transistor Q3 exceeds the trigger voltage Ttr of a trigger diode D3 and the diode D3 comes to a conduction state, a charge of the capacitor C1 flows into a base of a transistor Q2 and oscillation begins. When the output voltage of the secondary winding C of the high-frequency transformer T1 becomes high, a charging time of the capacitor C1 becomes longer and a starting phase of high frequency oscillation gets delayed, resulting in stabilization of the voltage to be applied to the halogen lamp L1.</p> |
