Teach you how to use a multimeter to determine the positive and negative poles of an electrolytic capacitor

In electronic circuit design, electrolytic capacitors pass AC and block DC, and are also used to store and release charge to act as filters and smooth out pulsating signals. How do you distinguish the positive and negative poles of electrolytic capacitors in circuit design? Connecting them the wrong way is dangerous, and large-capacity capacitors may even explode. Let's follow the editor to see how to use a multimeter to determine the positive and negative poles of electrolytic capacitors.

1. Introduction to electrolytic capacitors

Electrolytic capacitor is a type of capacitor. The metal foil is the positive electrode (aluminum or tantalum), the oxide film (aluminum oxide or tantalum pentoxide) close to the positive electrode is the dielectric, and the cathode is composed of conductive materials, electrolytes (the electrolyte can be liquid or solid) and other materials. The electrolyte is the main part of the cathode, so the electrolytic capacitor is named. At the same time, the positive and negative electrodes of the electrolytic capacitor must not be connected incorrectly.

Electrolytic capacitors are divided into two types: non-polar and polar. Non-polar electrolytic capacitors use a double oxide film structure, which is similar to two polar electrolytic capacitors with two negative poles connected together; polar electrolytic capacitors usually play the role of power supply filtering, decoupling, signal coupling, time constant setting, and DC isolation in power supply circuits or medium-frequency and low-frequency circuits.

2. The role of electrolytic capacitors

Electrolytic capacitors are widely used in household appliances and various electronic products. Polarized electrolytic capacitors usually play the role of power supply filtering, decoupling, signal coupling, time constant setting, DC isolation, etc. in power circuits or medium-frequency and low-frequency circuits. Non-polarized electrolytic capacitors are usually used in speaker divider circuits, TV S correction circuits, and single-phase motor starting circuits. The functions of electrolytic capacitors are mainly divided into the following categories:

1) DC isolation: its function is to prevent DC from passing through but allow AC to pass through.

2) Filtering - In the power supply circuit, the rectifier circuit converts AC into pulsating DC, and a larger-capacity electrolytic capacitor is connected after the rectifier circuit to utilize its charging and discharging characteristics (energy storage function) to convert the rectified pulsating DC voltage into a relatively stable DC voltage.

3) Coupling effect: In the process of transmitting and amplifying low-frequency signals, capacitor coupling is often used to prevent the static working points of the two circuits from affecting each other. As a connection between the two circuits, it allows the AC signal to pass through and be transmitted to the next circuit.

4) Bypass-provides a low impedance path for certain parallel components in an AC circuit.

5) Energy storage--Storing electrical energy for release when needed.

6) Temperature compensation: Compensate for the impact of insufficient temperature adaptability of other components and improve circuit stability.

7) Tuning - System tuning of frequency-dependent circuits, such as mobile phones, radios, and televisions.

3. Use a multimeter to determine the positive and negative poles of the electrolytic capacitor

Electrolytic capacitors have positive and negative poles. Generally, the one with a longer pin is the positive pole and the one with a shorter pin is the negative pole, and they are marked with a "1".