I. Reading method of ceramic capacitor
1. Method of representation of capacitor capacity
The basic unit of capacitor capacity is “farad” (F), 1/1000000 (millionth) of 1 farad is 1 micromethod (μF), 1/1000000 of 1 micromethod is 1 PF (1 picomethod or 1 picomethod). The relationship between them is a million (or 10 to the sixth) carry relationship.
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We commonly used capacitors are:
1) Electrolytic capacitance: most of the above 1μF, directly represented by numbers. Such as: 4.7μF, 100μF, 220μF and so on. The two poles of this capacitor are positive and negative, with the long legs being positive.
2) Capacitance of ceramic: most of them are below 1μF, directly expressed by numbers. For example, 10, 22, 0.047, 0.1, and so on. If expressed as an integer, the unit defaults to pF; For decimal notation, the default unit is μF. In the above example, they are 10P, 22P, 0.047μF, 220μF, etc.
Now there is another expression method similar to color ring resistance (unit default pF) popular in the world:
For example, “473” is 47000pF=0.047μF, “103” is 10000pF=0.01μF, etc. The first and second digits of “XXX” are valid digits, and the third digit represents the number of added 0. This notation has become quite common.
2. Reading method of ceramic capacitor
The reading method of ceramic capacitor and the reading method of resistance are basically the same, color standard method, number standard method and direct standard method. The basic unit of ceramic capacitor is farad (F), other units are: millimeter (mF), micrometer (μF), nano method (nF), skin method (pF). Where: 1 Fara =1000 milf (mF), 1 milf =1000 micromethod (μF), 1 micromethod =1000 nm (nF), 1 nm =1000 picograms (pF).
The capacity of large-capacity ceramic capacitor is directly marked on the capacitor, such as 10μF/16V;
The capacitance value of the small capacitor is represented by letters or numbers on the capacitor;
Letters: 2m=2000μF, 1P2= 1.2pf, 2n=2000PF;
Digital representation: Three-digit representation is also called capacitance digital representation. The first two digits of the three-digit number are the significant digits of the nominal capacity, and the third digit represents the number of zeros following the significant digit, both in pF.
For example, 102 indicates that the nominal capacity is 1000pF. 211 indicates that the nominal capacity is 210pF. 214 represents a nominal capacity of 21×10 (4) pF.
A special case in this notation is when the third digit is represented by “9”, the capacity is represented by multiplying the significant digit by 10 to the -1 power. For example, 219 indicates that the nominal capacity is 21x (10-1) pF=2.2pF.
What are the specifications of ceramic capacitors
1, high voltage ceramic capacitor, generally withstand voltage above 1KV.
2, medium voltage ceramic capacitor, generally refers to 100-1kV.
3, low voltage ceramic capacitor, generally refers to 100V below.
As for the model: just like ordinary capacitors, the basic capacity has. It’s all in the 1P-104PF.
The capacitance of ceramic chip capacitor is generally in pF (10 to the power of -12 F) as the unit. Early products are mostly marked directly, such as 1000P and 220P. The first two digits are the significant number of capacitance, and the last digit is the number of zeros added after it. For example, 102 indicates that the significant number is 10, and 2 indicates that two zeros are added after it, i.e. 1000pF. 221 is a valid number 22, and 1 is followed by a 0, which is 220pF.
Three, what is the role of ceramic capacitor
Ceramics capacitor is often used in audio and high frequency electronic circuit, common ceramics capacitor capacity is small, generally from several pf to tenths of uf, it and other kinds of capacitance in essence function, are blocking circulation exchange, but the frequency characteristic of ceramics capacitors is better, generally in a circuit plays a filtering, coupling, lotus root, shock, etc.
1, filtering effect: in the power supply circuit, the rectifier circuit will turn THE AC into a pulsating DC, and after the rectifier circuit access to a large capacity of electrolytic capacitor, using its charge-discharge characteristics, make the pulsating DC voltage after the rectifier into a relatively stable DC voltage. As capacitors with large capacity generally have certain inductance, they can not filter high frequency and pulse interference signals effectively. Therefore, a capacitor with a capacity of 0.001-0.lpf is connected in parallel at both ends to filter high frequency and pulse interference.
2. Coupling effect: In the transmission and amplification process of low-frequency signals, capacitance coupling is often used to prevent the static working points of the front and back circuits from influencing each other.
3. Decoupling: remove the voltage fluctuation caused by the power supply caused by each part of the circuit, so as to avoid the interference of each circuit caused by these fluctuations.
4, concussion action: ceramic capacitor and parallel inductor for energy exchange, repeated charging and discharging, and inductor shock.
The above is only the main role of the ceramic capacitor, the role of the ceramic capacitor is more than this, in addition to other roles, such as: resonance, frequency selection, bypass, vibration elimination and so on.