Polarity discrimination of crystal diodes 2

Date:2025-08-28 Categories:Product knowledge Hits:251 From:Guangdong Youfeng Microelectronics Co., Ltd


The positive and negative poles of a crystal diode can be distinguished according to the following methods:

1. Look at the symbol markings on the casing: Usually, the symbol of the diode is marked on the casing of the diode. (Refer to Figure 3), the end marked with a triangular arrow is the positive pole, and the other end is the negative pole.

2. Look at the color dots marked on the casing: On the casing of the point contact diode, there are usually color dots (white or red) marked. Except for a few diodes (such as 2AP9, 2AP10, etc.), the end marked with the color point is generally the positive terminal.

3. Looking at the contact pins through the glass: For point contact glass shell diodes, if the markings have been worn off, gently scrape off a little of the paint layer (black or white) on the shell. Look through the glass and see that the other end is a metal contact pin and the other end is an N-type germanium sheet. The end with a metal contact pin is the positive electrode.

4. Use a multimeter with R * 100 or R * 1K settings to measure the two leads of a diode. If the measured resistance is only a few hundred ohms (forward resistance), then the lead connected to the black probe (i.e. the positive terminal of the battery in the multimeter) is the positive terminal, and the lead connected to the red probe (i.e. the negative terminal of the power supply in the multimeter) is the negative terminal.



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