Testing diodes with an adjustable DC power supply

1. Use an adjustable DC power supply to measure the voltage value of the Zener diode

Use a 0~30V continuously adjustable DC power supply. For voltage regulator diodes below 13V, the output voltage of the voltage regulator can be adjusted to 15V. Connect a 1.5kΩ current limiting resistor in series to the positive pole of the power supply and then connect it to the negative pole of the voltage regulator diode to be tested. Connect the negative pole of the power supply to the positive pole of the voltage regulator diode. Then use a multimeter to measure the voltage value across the voltage regulator diode. The measured reading is the voltage regulator value of the voltage regulator diode. If the voltage regulator value of the voltage regulator diode is higher than 15V, the voltage regulator should be adjusted to more than 20V.

A megohmmeter lower than 1000V can also be used to provide test power for the voltage regulator diode. The method is: connect the positive terminal of the megohmmeter to the negative terminal of the Zener diode, and then connect the negative terminal of the megohmmeter to the positive terminal of the Zener diode. Then shake the handle of the megohmmeter at a prescribed uniform speed, and at the same time use a multimeter to monitor the voltage across the Zener diode (the voltage range of the multimeter should depend on the size of the stable voltage value). When the voltage indicated by the multimeter is stable, this voltage value is the stable voltage value of the Zener diode.

If the stable voltage value of the Zener diode measured by the adjustable DC power supply fluctuates, it means that the diode is unstable.

2. Detection of Bidirectional Trigger Diode

Use a 0~50V continuously adjustable DC power supply, connect the positive pole of the power supply in series with a 20kΩ resistor and then connect it to one end of the bidirectional trigger diode, connect the negative pole of the power supply in series with the current range of the multimeter (set it to 1mA) and then connect it to the other end of the bidirectional trigger diode. Gradually increase the power supply voltage. When the ammeter pointer swings significantly (more than tens of microamperes), it means that the bidirectional trigger diode is turned on. At this time, the voltage value of the power supply is the turning voltage of the bidirectional trigger diode.