How to judge whether the thyristor is good or bad by triggering circuit

How to judge whether the thyristor is good or bad by triggering circuit

Bidirectional thyristors are widely used, but their electrical characteristics are very special. Sometimes it is difficult to accurately measure their quality with a multimeter. Now a simple trigger circuit is used to accurately judge the quality of the thyristor by turning on and off the light bulb. .

Method description:

1. As shown in the figure, the 1st pin is T1 pin, the 2nd pin is T2 pin, and the 3rd pin is G pin. Use the 1K resistance range or diode range of the multimeter to measure: T1--T2 resistance value is infinite, T1--G resistance value Between 90--200Ω, the resistance of T2--G is infinite (no matter how the red and black test leads are swapped).

2. When the switch connected to pin 2 of the optocoupler is turned on, the light bulb does not light up. When the switch is turned on, the light bulb lights up. When the switch is turned off, the light bulb goes out. The thyristor is good.

3. When the switch connected to pin 2 of the optocoupler is turned on and the bulb lights up (even slightly), the thyristor is bad.

4. When the switch connected to pin 2 of the optocoupler is turned on, the light bulb does not light up. When the switch is turned on, the light bulb lights up. When the switch is turned off, the light bulb still lights up. The thyristor is bad.