“This article will explain the pin positive and negative identification methods of ordinary electrolytic capacitors, chip aluminum electrolytic capacitors, chip tantalum electrolytic capacitors, trimmer capacitors and variable capacitors.

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This article will explain the pin positive and negative identification methods of ordinary electrolytic capacitors, chip aluminum electrolytic capacitors, chip tantalum electrolytic capacitors, trimmer capacitors and variable capacitors.

Ordinary electrolytic capacitor:

Recognition method 1: The capacitor marked with “–” on the shell is the negative pole, and the other pole is the positive pole. The negative electrode is generally off-white in color, and the positive electrode is mostly black at one end.

Identification method 2: In the newly-purchased capacitors, which are both unused, the longer of the two pins represents the positive electrode of the capacitor, and the short one represents the negative electrode of the capacitor.

It should be noted that the capacitors are divided into positive and negative poles, which are called electrolytic capacitors. When the polar capacitor works normally in the circuit, the voltage of its positive and negative poles should be strictly the same as the positive and negative polarity of the power supply. Once the polarity of the external power supply voltage is reversed and applied to the electrodes of the electrolytic capacitor, the electrolytic capacitor will have a great impact. To leakage current, this leakage current will cause the electrolytic capacitor to rapidly increase in temperature.

Moreover, as the temperature of the capacitor rises, the leakage current will further increase in a very short time, resulting in a very strong vicious circle. The temperature of the capacitor rises rapidly to the limit that it can withstand in a very short time, and the capacitor will be In a short period of time, due to the sharp rise of its own temperature, burst damage occurs, and with a loud burst sound, the capacitor is completely damaged by burst.

How to identify SMD aluminum electrolytic capacitors and SMD tantalum electrolytic capacitors:

The purpose of putting two capacitors together is to distinguish the difference between the positive and negative poles of the two capacitors. The aluminum electrolytic capacitor is cylindrical in shape, and the positive and negative poles are identified by a black mark on the top of the capacitor. The black part is the negative pole, and the other pole is the positive pole. The shape of the tantalum electrolytic capacitor is a rectangular parallelepiped. One pole with stripes is the positive pole (remember), and the other pole is the negative pole.

Positive and negative identification of fine-tuning capacitors and variable capacitors:

Identify the fine-tuning capacitor (that is, the kind of capacitor that is fine-tuned by a screwdriver). This kind of fine-tuning capacitor generally does not have very strict requirements on the positive and negative electrodes of the capacitor. However, in order to prevent the process of adjusting the capacitor from affecting the circuit board system, the moving piece is usually It is defined as the negative pole connected to the ground of the circuit board, and the other pole is positive. The positive and negative identification of the variable capacitor is the same as that of the fine-tuning capacitor, but the dynamic pin of the variable capacitor is easier to distinguish. Generally, for a single variable capacitor, the pins at both ends are fixed, generally connected to the positive pole, and the middle pin is active, connected to the negative pole of the circuit.

Link to this article：How to identify the positive and negative poles of the capacitor pins, and what are the methods?