Capacitance is a physical quantity that characterizes the ability of a capacitor to hold charge. The amount of electricity required to increase the potential difference between the two plates of a capacitor by 1 volt is called the capacitance of the capacitor. The symbol for capacitance is C. Capacitors are one of the most widely used electronic components in electronic equipment, and are widely used in DC blocking, coupling, bypassing, filtering, tuning circuits, energy conversion, control circuits, etc. Use C to represent the capacitance, and the capacitance units are farad (F), microfarad (uF), picofarad (pF), 1F=10*6uF=10*12pF
1 farad (F) = 1,000,000 microfarads (μF) 1 microfarad (μF) = 1000 nanofarads (nF) = 1,000,000 picofarads (pF)
Model naming method of capacitors: The model of domestic capacitors generally consists of four parts (not applicable to pressure-sensitive, variable, and vacuum capacitors). In turn represent name, material, classification and serial number.
The method of judging the polarity of electrolytic capacitors: use a multimeter to measure it, first discharge the electrolytic capacitors, and then connect the test leads to both ends. negative, the digital meter is opposite, and, between measurements, the capacitor must discharge. (2) Use the length of the pins to distinguish the positive and negative electrodes. The long leg is positive and the short leg is negative. The black block with the mark on the capacitor is the negative electrode. There are two semicircles on the capacitor position on the PCB, and the pin corresponding to the colored semicircle is the negative pole.
Classification of capacitors:
According to its polarity, it is divided into two categories: polar capacitors (such as electrolytic capacitors) and non-polar capacitors.
According to the structure, it is divided into three categories: fixed capacitors, variable capacitors and trimmer capacitors.
According to the classification of electrolytes, there are: organic dielectric capacitors, inorganic dielectric capacitors, electrolytic capacitors and air dielectric capacitors.
Divided by use: high frequency bypass, low frequency bypass, filtering, tuning, high frequency coupling, low frequency coupling, small capacitors.
Capacitor capacity indicates:
1. Direct mark method: mark directly with numbers and unit symbols. For example, 01uF means 0.01 microfarads, and some capacitors use "R" to represent the decimal point, such as R56, which means 0.56 microfarads.
2. Text symbol method: Use a regular combination of numbers and text symbols to represent capacity. For example, p10 means 0.1pF, 1p0 means 1pF, 6P8 means 6.8pF, and 2u2 means 2.2uF.
3. Color scale method: use the color circle or color point to indicate the main parameters of the capacitor. Capacitors are color-coded in the same way as resistors.
Capacitor deviation signs: +100%-0--H, +100%-10%--R, +50%-10%--T, +30%-10%--Q, +50%-20% --S, +80%-20%--Z.
Commonly used capacitors: aluminum electrolytic capacitors, tantalum electrolytic capacitors, film capacitors, ceramic capacitors, monolithic capacitors, paper capacitors, trimmer capacitors, ceramic capacitors, glass glaze capacitors, mica and polystyrene dielectric capacitors.
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