Tell you about Zener diode identification and detection
Zener diode is one of the common components in electronic circuits, especially power circuits. Unlike ordinary diodes, it often works in the reverse breakdown area of the PN junction. As long as its power consumption does not exceed the maximum rating, it will not be damaged. . Next, I will tell you how to identify and detect Zener diodes.

Huixin tells you the identification and detection of Zener diodes

1. Identification of Zener Diode

Common Zener diodes have two pins, but there are also a few Zener diodes with three pins (such as 2DW7). In addition to identifying them by the logo on the shell, beginners should learn to use a multimeter to distinguish between Zener diodes and ordinary diodes.

(1) How to identify the positive and negative poles of Zener diodes. The identification method of the positive and negative poles of Zener diodes is the same as that of ordinary diodes. The different characteristics of PN junction forward and reverse resistance can be used for identification. In practice, the R×1k file of an analog multimeter is commonly used to measure the resistance value between the two pins. Measure again after swapping the red and black test leads. In the smaller of the two measured resistance values, the pin connected to the black test lead is the anode of the Zener diode, and the pin connected to the red test lead is the cathode. The three-pin Zener tube looks like a triode, but inside it is two Zener diodes connected to the anode. The method for identifying the positive and negative poles of the Zener tube is the same as the two-pin Zener tube, only the common anode (ie, the pin) is measured, and the other two pins are both negative.

(2) How to distinguish between ordinary diodes and Zener diodes. First set the multimeter to the R×1k file, and measure the positive and negative poles of the diode according to the aforementioned method; then connect the black test lead to the cathode of the tested diode and the red test lead to the anode of the diode. The measured value is the reverse resistance of the PN junction at this time, and the resistance is very high. Large, the hands do not deflect. Then switch the multimeter to the R×10k file. At this time, if the needle is deflected to the right by a certain angle, it means that the measured diode is a Zener diode; if the needle does not deflect, it means that the measured diode may not be a Zener diode (Note: The above method is only suitable It is used to measure the voltage stabilizer diode whose voltage is lower than the R×10k gear battery voltage of the multimeter).
The principle of the above measurement method is that the battery voltage in the multimeter's R×10k gear is much higher than that of the R×1k gear. If the voltage stabilization value of the Zener diode is lower than the battery voltage, the R×10k gear is used to measure the voltage. The PN junction of the diode will zener breakdown, showing that the resistance reading drops a lot. The reverse withstand voltage of ordinary diodes is relatively high, and the battery voltage in the meter of R×10k is not enough to make it reverse breakdown. Of course, if the voltage regulation value of the Zener diode is higher than the battery voltage in the watch, the watch needle will not deflect, and the type of the tested diode cannot be distinguished by the above method.



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