| 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 shortcircuiting by a thyristor between the secondary side output windings of a transformer, thereby reducing the number of parts. CONSTITUTION:An one-element forward converter associated with an over voltage protecting circuit 1 turns ON and OFF a switching transistor Q1 by utilizing the induced voltage of the feedback winding P2 of a transformer T, converts a DC into an AC, rectifies and smoothes the output of the secondary side output winding S1 and outputs a DC voltage Vout. This circuit 1 has a series circuit of a diode D 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 becomes an overvoltage, the diode ZD is conducted to fire the SCr to shortcircuit between the windings S1. |
