| 摘要 |
PURPOSE:To prevent a transistor from being damaged by detecting a current flowing to a protecting diode connected in parallel with the transistor at the time of short-circuiting a load and delaying the timing of a starting trigger. CONSTITUTION:A transistor inverter is composed as a half bridge of a full-wave rectifier 2 connected to an AC power source 1, a capacitor 3, transistors (Tr) 14, 15, a series unit of a resistor 4 and a capacitor 5, a trigger element 10, and capacitors 18, 19. In this case, protecting diodes 11, 21 are connected in parallel with the Trs 14, 15, a resistor 13 is connected in series, and a Tr 6, a capacitor 7, a diode 9, etc., are provided. Thus. a negative current flows through the resistor 13 to the diode 12 at the time of short-circuiting a load 23 to charge a capacitor 8 by the voltage across the diode, the Tr 6 is turned ON to delay the timing of the starting trigger. As a result, it comes into an intermittent oscillation state to prevent the Trs 14, 15 from being damaged.
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