First, resistorResistance in the circuit with “r” number, such as: R15 resistance of the number 15. Resistance is a most common used PCB parts. Its PCB electronic components symbol looks like a tiny rectangle. It is in the circuit of the main function for the shunt, current-limiting, partial pressure, offset, filter (used in combination with capacitors) and impedance matching, and so on. Parameter identification: the unit of resistance in ohms (ω), magnification: kiloohm (kΩ), megohms (MΩ). Conversion methods are: 1 mega-ohm = 1 million euro = 1000000 euro Parameter annotation 3 ways of resistance, namely direct method, method of color and array methods. Method is mainly used for patches and other smaller circuits, such as: 472 47×102 Omega (4.7K); 104 indicates a 100K-ring marking method using a maximum, for example as follows: Four five-color ring color ring resistance resistors (precision resistor) resistor colour location and rate relationships as shown in the following table: Effective digital color ratio allowable deviation (%) Silver/10-2 ± 10 Gold/10-1 ± 5 Black 0/100 Brown 1 101 ± 1 Red 2-102 ± 2 Orange 3/103 Yellow 4/104 The Green 5 105 ± 0.5 Blue 6-106 ± 0.2 Purple 7 107 ± 0.1 Gray 8/108 White 9 109 + 5 to-20 Colorless//± 20
Second, capacitance1, generally used in the capacitor in the circuit “c” plus number (C25 capacitance representing the number 25). Capacitor is made of two pieces of metal film close to, Middle separated by insulating material and circuit board components. Capacitance characteristics of main is across the straight flow of communication. Capacitor size is large enough to store electricity, the effect known as capacitive reactance of capacitors for AC signals, it concerns with the AC signal frequency and capacity. Capacitive XC=1/2 pi f c (F AC signal frequency, capacitance c) Telephones commonly used types of capacitor electrolytic capacitors, ceramic capacitors, chip capacitors, multilayer ceramic capacitors, tantalum capacitors with polyester capacitors and so on. 2, recognition: recognition method of capacitance and resistance identification methods are basically the same, straight standard method, method, and method 3. The basic unit of capacitance farad (f) that the other units are: millifarad (mF), micro-methods (uF), nanofarad (nF), law (pF). Of which: 1 =109 na =106 micro-farad = 103 method method method method for skin = 1012 high capacity capacitor capacity value is directly marked on the capacitor, such as 10 uF/16V Small capacitor capacity value on the capacitance of a letter or number Letter representation: 1M=1000 uF 1P2=1.2PF 1n=1000PF Digital representation: general use three digits indicate the size, two significant digits, and the third number is the ratio. Example: 102 10x102PF=1000PF 224 22x104PF=0.22 uF 3, capacitance errors table Symbol FGJKLM Tolerance ± ± 1% ± 5% ± 10% ± ± 20% Such as: a ceramic capacitors is 104J capacity is 0. 1 uF, error is ± 5%. 4, fault characteristics In the actual repair, capacitor failure are mainly as follows: (1) pin broken circuit fault caused by corrosion. (2) removal of welding and virtual open fault. (3) the smaller capacity or open circuit failure resulting from the leakage. (4) leakage, serious leakage and breakdown.
Third, the versatileCrystal diodes in the circuit used the “d” number, such as: D5 No 5 diode. 1, function: the main feature is a one-way electric conductivity of diode, that is, in the presence of forward voltage, conduction resistance is small and great for under reverse voltage resistance or infinity. Because diodes having the above characteristics, cordless telephone are often used in rectifying it, isolation, voltage, polarity protection, code control, frequency modulation and static noise in the circuit. Crystal diodes used in radio can be classified by function: a rectifier diode (1N4004), blocking diode (1N4148), Schottky diodes (such as BAT85), light emitting diode, Zener diode, etc. 2, recognition: recognition of diodes is very simple, low-power diode n pole (cathode), most diodes surface using a color circle marked, some diode diode special notation for p (positive) or n pole (cathode), also use symbols for “p” and “n” to determine the polarity of the diode. Light emitting diode polarity can be identified from the PIN length, long, short legs are negative. 3, testing Note: when you use a digital multimeter to test a diode, Red form the cathode of the diode, black anode of the diode when measured resistance is the diode conduction resistance, this analog multimeter meter connection is exactly the opposite. 4, commonly used in 1N4000 series diode voltage is set out below: Model 1N4001 1N4002 1N4003 1N4004 1N4005 1N4006 1N4007 Withstand voltage (v) 50 100 200 400 600 800 1000 Current (a) are 1
Four, Zener diodeZener diode in the circuit used the “ZD” plus number, such as: ZD5 regulator of the number 5. 1, the Zener diode voltage principle: Zener diode characteristic is that after the breakdown, the voltage remains the same at both ends. In this way, when the circuit voltage regulator tubes later, because fluctuations in the supply voltage, or other reasons when all points of the circuit voltage, the load voltage will remain the same at both ends. 2, fault characteristic: Zener diode failure mainly in open circuit, short circuit and the voltage value is unstable. These 3 kinds of failure, a failure before showed increased supply voltage; 2 after failed performance for low supply voltage to zero volts or output is unstable. Common Zener diode model and voltage values in the following table: Number 1N4728,1N4729,1N4730,1N4732,1N4733,1N4734,1N4735,1N4744,1N4750,1N4751,1N4761 Voltage value 3.3V,3.6V,3.9V,4.7V,5.1V,5.6V,6.2V,15V,27V,30V,75V
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