Photodiode is a kind of detector, which can convert light into electricity or signal. In various regions of the world, the application range of this product is relatively wide. However, there are many photodiodes on the market, the quality of which is far from the qualified diode standards we use.

　　 In any case, the quality problems of photodiodes are more serious. After we buy photodiodes, we can check with methods to determine whether there are any problems. Generally speaking, when we detect the photodiode, it is usually a resistance file, and a multimeter Rx1k can be used. At this time, when there is no light in the photodiode, it is actually similar to the appearance of an ordinary diode. To conduct electricity only. When the forward resistance value is 8-9kΩ, it can only be detected when the reverse resistance value is greater than 5MΩ.

　　 When we are testing, if we do not know the positive and negative poles of the photodiode, we can also use the general positive and negative poles and measuring ordinary diodes to help ourselves determine. That is to say, when the forward resistance is measured, the position where the black test lead is locked in the hand is very close to the phase of the photodiode. In this process, we can first illuminate the photodiode with light, and then observe the deflection range of the multimeter.