Tell you the Zener diode identification and detection

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

1. Identification of Zener diode

Common Zener diodes have two pins, but there are also a few Zener diodes for three pins (such as 2DW7). In addition to the identification of the outer casing, beginners should learn to use a multimeter to distinguish between Zener diodes and ordinary diodes.

(1) Identification method of positive and negative voltage regulator diodes. The identification method of the positive and negative poles of the Zener diode is the same as that of the ordinary diode. It can be identified by the different characteristics of the positive and negative resistances of the PN junction. In practice, the R×1k file of the pointer multimeter is commonly used to measure the resistance between the two pins. Red and black test leads are exchanged and measured again. The smaller of the two measured resistance values, the pin connected to the black test lead is the positive pole of the Zener diode, and the pin connected to the red test lead is the negative pole. A three-pin Zener is similar in shape to a triode, but internally has two Zener diodes connected to the positive pole. The identification method of the positive and negative poles of the voltage regulator tube is the same as that of the two-pin voltage regulator tube, and only the common positive pole (ie, the first leg) is measured, and the other two legs are the negative poles.

(2) The method of distinguishing between a normal diode and a Zener diode. First set the multimeter to R×1k file, measure the positive and negative poles of the diode according to the above method; then connect the black test lead to the negative pole of the diode to be tested, and connect the red test lead to the positive pole of the diode. At this time, the reverse resistance of the PN junction is measured, and the resistance is very high. Large, the hands are not deflected. Then convert the multimeter to R×10k file. If the hand is deflected to the right by a certain angle, the diode to be tested is a Zener diode; if the hand is not deflected, the diode to be tested may not be a Zener diode (Note: The above method is only suitable) For measuring the voltage regulator diode whose voltage is lower than the R×10k battery voltage of the multimeter.

The principle of the above measurement method is that the internal battery voltage of the multimeter R×10k file is much higher than the R×1k file. If the voltage regulator diode is lower than the battery voltage, the voltage is measured by R×10k. The diode's PN junction will be pinched down, showing a much lower resistance reading. The reverse voltage of the common diode is high, and the battery voltage in the R×10k file is not enough to reverse the breakdown. Of course, if the voltage regulator diode is higher than the battery voltage in the meter, the hands will not be deflected. The above method cannot distinguish the type of diode under test.