1. The capacitor is generally represented by “C” plus numbers in the circuit (such as C13 means the capacitor numbered 13). The capacitor is composed of two metal films close to each other, separated by an insulating material in the middle. The characteristics of the capacitor are It is DC to AC.

The size of the capacitor capacity is the amount of electrical 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.

Capacitance XC = 1 / 2πf c (f represents the frequency of the AC signal, C represents the capacitance)

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

2. Identification method: The identification method of the capacitor is basically the same as the identification method of the resistor, which is divided into three types: the straight standard method, the color standard method and the number standard method. The basic unit of the capacitor is expressed by Farah (F), and the other units are: millifa (mF), microfarad (uF), nanofarad (nF), picofarad (pF).

Among them: 1 farad = 103 millifarad = 106 microfarad = 109 nanofarad = 1012 picofarad

The capacitance value of a large-capacity capacitor is directly marked on the capacitor, such as 10 uF / 16V

The capacitance value of a capacitor with a small capacity is represented by letters or numbers on the capacitor

Letter notation: 1m = 1000 uF 1P2 = 1.2PF 1n = 1000PF

Digital representation: Generally, three digits are used to indicate the size of the capacity, the first two digits represent significant digits, and the third digit is the magnification.

For example: 102 means 10 × 102PF = 1000PF 224 means 22 × 104PF = 0.22 uF

3. Error table of capacitance

Symbol: F G J K L M

Allowable error ± 1% ± 2% ± 5% ± 10% ± 15% ± 20%

For example: a ceramic capacitor of 104J indicates a capacity of 0.1 uF and an error of ± 5%.