How to measure the quality of diodes?

A diode is a common type ofElectronicsComponents are widely used in various electronic devices. However, before using diodes, we need to confirm their quality through measurement. This article will provide a detailed analysis of how to measure the quality of diodes, including their usageA multimeterandOscilloscopeTwo conventional measurement methods and how to determine whether the diode is working properly based on the measurement results.

1、 Method of measuring the quality of diodes using a multimeter

1. Preparation work:

a. Choose the appropriate measurement range, usually voltage V orresistanceR gear;

b. Switch the multimeter to diode test mode, which is marked withDiodeSymbol (arrow pointing to a vertical line segment);

c. Ensure that the diode has been removed from the circuit to prevent interference with the measurement results.

2. Positive voltage measurement:

a. Connect the positive terminal of the multimeter test pen to the positive terminal (marked end) of the diode and the negative terminal to the negative terminal (unmarked end) of the diode;

b. Record the voltage value displayed on the multimeter;

c. If the displayed voltage value is positive and close to the usual value (usually 0.7V), it indicates that the diode is working normally in the forward direction;

d. If the displayed voltage value is 0 or close to infinity (open circuit state), it indicates that the diode may be broken.

3. Reverse voltage measurement:

a. Connect the positive terminal of the multimeter test pen to the negative terminal of the diode, and connect the negative terminal to the positive terminal of the diode;

b. Record the voltage value displayed on the multimeter;

c. If the displayed voltage value is 0, it indicates that the diode is conducting electricity during reverse operation and may be damaged;

d. If the displayed voltage value is infinite (open circuit state), it indicates that the diode is non-conductive during reverse operation and is working normally.

4. Accurate testing:

a. If more accurate test results are needed, a multimeter can be used to measure the resistance value at both ends of the diode;

b. Set the multimeter to the resistance position and connect the test pen to both ends of the diode;

c. If the measurement result shows a resistance value of zero or extremely low, it indicates that the diode is normal;

d. If the measurement result shows an infinite resistance value, it indicates that the diode may be broken.

2、 Method of measuring the quality of diodes using an oscilloscope

1. Preparation work:

a. Switch the oscilloscope to X-Y mode;

b. Connect the probes of the oscilloscope, connect one probe to the positive terminal of the diode and the other probe to the negative terminal of the diode;

c. Ensure that the oscilloscope and diode are powered on.

2. Observe the displayed image:

a. In X-Y mode, a normal diode should display a positive straight line;

b. If the oscilloscope displays a negative straight line, it indicates that the diode may be damaged;

c. If the oscilloscope displays flat graphics or waveforms, it indicates that the diode may be short circuited or open circuited.

3. Observe cut-off and saturation voltage:

a. Observe the cut-off voltage of the diode during forward operation and the saturation voltage during reverse operation within the normal working range;

b. If the cut-off voltage or saturation voltage of the diode deviates from the usual value (the cut-off voltage is usually 0.7V when working in the forward direction, and the saturation voltage is usually infinite when working in the reverse direction), it indicates that there may be a problem with the diode.

Conclusion:

By using two measurement methods, multimeter and oscilloscope, we can accurately judge the quality of diodes. If the diode meets the usual voltage standards in both forward and reverse operation, and the resistance value is appropriate, it can be confirmed that the diode is working properly. If the diode does not meet the standards during the measurement process, it is possible that the diode is damaged and needs to be replaced.

Therefore, in the process of electronic circuit designrepairMeasuring the quality of diodes during debugging is a very important task.