Capacitance is a passive component that we often use in circuits. Several types of aluminum electrolytic capacitors, filter capacitors, tantalum capacitors, and chip ceramic capacitors are often seen. Due to the nature of each capacitor, the corresponding application is different. So this article first introduces the basic knowledge of capacitors, and then compares the differences and characteristics of several capacitors, and summarizes the techniques for selecting capacitors in actual circuits.

1. Classification and function of capacitors

The capacitor consists of two metal poles with insulating material (dielectric) in the middle. The types of capacitors made up of different insulating materials vary:

(1) According to the structure can be divided into: fixed capacitor, variable capacitor, trimmer capacitor.

(2) According to the dielectric material can be divided into: gas dielectric capacitor, liquid dielectric capacitor, inorganic solid dielectric capacitor, organic solid dielectric capacitor electrolytic capacitor.

(3) According to the polarity is divided into: there are polar capacitors and non-polar capacitors. The most common thing we get is electrolytic capacitors.

(4) The capacitor has a function of blocking the direct current in the circuit and passing the alternating current.