How do I measure the forward and reverse resistance of a diode with a multimeter?

One and a half minute lesson: using an analog multimeter to measure the positive and negative electrodes of a diode is generally not used, but we need to understand the method.

The measurement voltage of the digital multimeter must be measured with the diode, and the measurement voltage of the other resistance gear is low (only left and right), and the diode cannot be conducted, so the diode can not be measured, and the positive value should be a stable value, which is the voltage drop at both ends of the diode. The reverse should not measure the value, which means infinity, and the fault is either a problem with your diode, or a problem with the meter, or a measurement problem.

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Generally, it is measured according to the characteristics of the diode, and it can also be measured with a multimeter resistance. The diode is a semiconductor device with unidirectional conductivity, which can be measured using a multimeter, and the main Jane Sui takes to check whether its unilateral conductivity is normal, so as to judge the quality of the diode.

Here's how:

1. Put the black watch pen plug on the multimeter in the public "com" jack, and the red watch pen in the "V" jack.

2. Turn the gear switch to "diode with buzzer" and press the power switch of the multimeter. When a "1" is displayed on the screen, the test can begin.

3. Contact the red watch pen with the positive pole of the diode, and contact the black watch pen with the negative pole, then the positive resistance value of the diode is displayed on the screen, which should be about 500 -700 under normal circumstances.

4. Swap two pens for reverse testing, because at this time, the starting symbol "1" is displayed on the screen, indicating that the reverse resistance value is "m". This situation indicates that the diode is good.

5. If the switching diode is tested forward and backward, the results are both "1" or "0", or the reverse test shows that it is not "1", etc., these situations indicate that the diode is broken and can no longer be used.

The forward resistance of the germanium diode is about 1000 and the reverse resistance is about 300.

The role of diodes includes rectifier circuits, detection circuits, voltage stabilization circuits, and various modulation circuits, which are mainly composed of Wu Dongsen diodes.

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If it is very small, it means that the diode is bad, and if the reverse resistance is very large, it means that the diode is good.

For such basic components, we should firmly grasp the principle of its action and the basic circuit, so as to lay a good foundation for the future study of electronic technology.

It is best to use an analogue multimeter to measure the positive and negative poles of a diode, because an analogue multimeter is more intuitive to block lead. Diodes have single-phase conductivity, and according to this characteristic, the positive and negative poles can be judged by measuring the resistance level. Here's how:

First of all, dial the watch to the RXK file, and put the two watch pens on both ends of the diode, at this time, if the watch hand swings quickly to the right (generally about 2K), then the end of the black watch pen is the positive pole, and the end of the red watch pen is the negative pole. As shown in Fig

Using the resistance file of the multimeter, you can preliminarily judge the normal opening condition of the diode. The specific steps are as follows:

1.Place the pen between the two pins of the diode and record the resistance value.

2.Turn the test pen upside down and put it back to get another resistance value.

3.If the two resistor values are the same or close to each other, the diode is correct. If the two resistors are large or infinite, the diode may be damaged or an open circuit breaker may be destroyed.

For the judgment of the positive and negative poles of the diode, the following methods can usually be used:

1.Observe the structure and markings of the diode, which may have text or graphic identification on one side.

2.On one side of the diode pin, the tester should be able to read the lower resistance value, which side is the positive side of the diode and the other side is the negative side.

It is important to note that when testing the diode above method, the test pen should be properly touched to the pin to avoid inaccurate resistance values read out.

The diode measures the positive socks and grinds the negative electrode:

When the digital multimeter is in the resistance mode, the voltage between the two meter pens is low, which is lower than the forward conduction voltage of the ordinary silicon diode, and the diode is in the cut-off stateThe resistance value in the cut-off state is very large, so when a diode is measured with a digital multimeter, it shows value overflow regardless of whether it is forward or backward. Expansive state.

Digital multimeters have diode measurement gears, which should be used to measure the forward and reverse on/off of the diodeIn addition, the diode is a nonlinear component, the resistance value is not fixed, when the forward conduction resistance of the diode is measured with the resistance level of the pointer multimeter, it can be seen that the difference between the resistance value of the same gear is very largeTherefore, it is of little significance to measure the resistance value of the diode with a multimeter, as long as the reed can measure the forward conduction, reverse cut-off, or to distinguish the positive and negative electrodes, and to distinguish whether there is breakdown or burnout, there is no need to read the specific resistance value

The digital multimeter has a special diode file for measuring diodesIf you have to use the resistance file, the diode reverse has a resistance value of more than tens of k, so the table shows overflow 1