| 摘要 |
A power transfer circuit includes a power transformer (2) having a center tap (12) provided in its secondary winding, a full-wave rectifier circuit (13), a level discriminator circuit (15) and a switching circuit (14). In response to a level discrimination made by the level discriminator circuit that a DC voltage outputted from one output terminal of the full-wave rectifier circuit is less than a predetermined voltage level, a transistor (Q1) and a thyristor (SCR) of the switching circuit are made conductive so as to ground the other output terminal of the full-wave rectifier circuit. In response to a level discrimination made by the level discriminator circuit that the DC voltage outputted from the said one output terminal of the full-wave rectifier circuit exceeds the predetermined voltage level, a diode (D9) connected to the center tap of the power transformer is made conductive to ground the center tap. Thus, the full-wave rectifier circuit outputs a constant DC voltage even if AC voltages at different levels are inputted in the primary winding of the power transformer. |
