| 摘要 |
PURPOSE:To obtain a highly reliable overvoltage protecting circuit by connecting an overvoltage detector between the secondary side rectified and smoothed output and the gate of a thyristor, and thereby firing the thyristor to shortcircuit between the secondary side output windings of a transformer. CONSTITUTION:A ringing choke converter associated with an overvoltage pro tecting circuit 1 turns ON and OFF a switching transistor Q1 by the voltage of the feedback winding P2 of a transformer T, and outputs a DC voltage Vout through rectifying and smoothing circuits D, C from the secondary side output winding S1. This circuit 1 has a series circuit of a diode D2 and a thyristor SCR inserted between the terminals of the secondary side output windings S1 and an overvoltage detector (Zener diode) ZD connected between the gate terminals of the SCR. Thus, when the output voltage Vout becomes an overvoltage, the diode ZD is conducted to fire the SCR to shortcircuit between the windings S1, thereby stopping the oscillation of the transistor Q1. |
