The capacitance subsidiary
1, the capacitance in circuit "C" and is commonly used in digital representation (such as the capacitance of C25 said Numbers for 25). Capacitor is made up of two pieces of metal film, close to the middle separated by insulating material and components. The characteristics of capacitance communication mainly blocking circulation.
The size of the capacitance is said to store electrical energy, the size of the capacitance effect is called the capacitive reactance of ac signal, it is associated with the frequency of the ac signal and capacitance. Capacitive reactance XC = 1/2 PI c f (f said the frequency of the ac signal, capacitance c said)
Telephone is commonly used in electrolytic capacitor, the kinds of ceramics capacitors, SMD capacitors, monolithic capacitors, tantalum capacitors, polyester capacitors, etc.
2, recognition methods: identification method of capacitance and resistance identification method of basic same, straight standard method, three kinds of color standard method and standard method. The basic unit of capacitance with ferrari (F), according to other units include: milli method (mF), micro method (uF), sodium (nF), leather (pF).
Including 1: ferrari = 103 = 106 micro method = 109 = 1012 skin method of large capacity capacitance on capacitance directly to mark its capacity values, such as 10 uF / 16 v capacity small capacitance of its capacity value on the capacitor with letters or Numbers
Letter notation: 1 m = 1000 uF p2 = 1.2 PF 1 n = 1000 PF
Digital representation: three figures show that the size, is commonly used in the former two significant figures, said the third digit ratio.
Such as: 102 said 10 x 102 = 1000 pf pf said 22 224 x 224 = 0.22 uF pf
Number 3, capacitance error table FGJKLM allowed error of plus or minus 1% plus or minus 2% plus or minus 5% plus or minus 10% plus or minus 15% plus or minus 20%
Such as: a ceramics capacitors is 104 j said capacity of 0. 1 uF, the error of plus or minus 5%.
4, fault characteristics
In the actual repair, capacitor failure mainly for:
(1) pin corrosion breaking open circuit fault.
(2) the desoldering and open-circuit fault of virtual welding.
(3) after discharge capacity or open circuit fault.
(4) leakage, serious leakage and breakdown of failure.