1、A capacitor is a component composed of two metal films that are close together and separated by insulating materials.

Capacitors are generally represented by "C" plus numbers in the circuit (for example, C13 represents the capacitor numbered 13).

The characteristics of capacitors are mainly to block DC and AC. The size of the capacitor capacity is the size of the electric energy that can be stored. The blocking effect of the capacitor on the AC signal is called capacitive reactance, which is related to the frequency and capacitance of the AC signal.

Capacitive reactance XC=1/2πfc (f represents the frequency of the AC signal, C represents the capacitance)

The types of capacitors commonly used in telephones include electrolytic capacitors, ceramic capacitors, chip capacitors, monolithic capacitors, tantalum capacitors and polyester capacitors.

2、recognition methods:

The identification method of capacitance is basically the same as that of resistance, and it is divided into three types: direct marking method, color marking method and number marking method.

The basic unit of capacitance is expressed in farads (F), and other units are: millifarads (mF), microfarads (uF), nanofarads (nF), and picofarads (pF). Among them: 1 Farad = 103 millifarads = 106 microfarads = 109 nanofarads = 1012 picofarads. The capacitance value of a capacitor with a large capacity is directly marked on the capacitor. For example, the capacitance value of a capacitor with a small capacity of 10uF/16V is indicated by letters on the capacitor. Or digital representation letter representation: 1m=1000uF1P2=1.2PF1n=1000PF Digital representation: Generally, three digits are used to represent the capacity, the first two digits represent significant digits, and the third digit is the magnification. For example: 102 means 10×102PF=1000PF224 means 22×104PF=0.22uF

3、Capacitor Capacity Error Table

Symbol FGJKLM

Allowable error±1%±2%±5%±10%±15%±20%

For example: a ceramic capacitor of 104J means that the capacity is 0.1uF, and the error is ±5%.