Today, the editor will tell you the basic knowledge of electronic components. The full text involves everything you want to know. Let’s take a look!
Identify common parts:
1. Resistance
The resistors in the circuit are represented by R and numbers, such as R15 for the resistor numbered 15. The main functions of resistors in a circuit are shunt, current limiting, voltage dividing, biasing, filtering (in combination with capacitors) and resistor matching.
Parameter identification: The unit of resistance is ohm (ω), and the unit of magnification is: kiloohm (KΩ), megohm (MΩ), etc. The conversion method is: 1 megohm = 1000 kiloohms = 1,000,000 Ohm.
There are three ways to label resistance parameters, namely direct labeling, color labeling and numerical labeling.
Digital magnification tolerance of valid colors (%)
Silver/10-2±10.
Gold/10-1±5.
Black 0100/Black
Brown 1101±1.
2102 ± 2 red.
3103/orange
Yellow 4104/
5105±0.5 green.
Blue 6106±0.2.
Purple 7107 ± 0.1.
8108/gray
White 9109+5-20.
Colorless //±20.
2. Capacitance
1. Capacitors are usually denoted by a C and a number (for example, C25 means a capacitor numbered 25). A capacitor consists of two elements close to a metal film, separated by an insulating material. Capacitors are mainly characterized by DC communication.
The size of the capacitor refers to the size of the stored electrical energy. Capacitance blocking an AC signal is called capacitive reactance and is related to the frequency and capacitance of the AC signal. Capacitance XC=1/2πFC.
(f is the frequency of the AC signal, C is the capacitance)
The types of capacitors commonly used in telephones include electrolytic capacitors, chip capacitors, monolithic capacitors, tantalum capacitors, polyester capacitors, etc.
2. Identification method: The identification method of capacitance is basically the same as that of resistance, which is divided into direct marking method, color marking method and number marking method. The basic unit of capacitance is expressed in farads (F), and other units include: m-farads (mf). Microfarads (uf). Nanofarads (nf). Picofarads (pf).
Among them: 1 farad = 103m method = 106 microfarad = 109 nanofarad = 1012 picofarad large capacity capacitor, its capacity value is directly marked on the capacitor, such as 10uf/16V.
Use letters or numbers to indicate the capacity value of small-capacity capacitors.
Letter notation: 1m=1000u1P2=1.2PF1n=1000PF.
Digital representation: Generally, three digits are used to represent the capacity, the first two digits represent significant digits, and the third digit is the magnification.
For example: 102 means 10×102PF=1000PF224 means 22×104PF=0.22uF.
3. Capacitance error table.
FGJKLM symbol.
Allowable error±1%±2%±5%±10%±15%±15%±20%
For example, a ceramic capacitor is 104J, which means that the capacity is 0.1uf. The error is ±5%.
4. Fault characteristics.
In actual maintenance, capacitor failures are mainly manifested as:
(1) Corrosion of pins leads to open circuit failure.
(2) Open circuit failure of desoldering and virtual soldering.
(3) Small capacity or open circuit failure after water leakage.
(4) Leakage. Serious leakage and breakdown failure.
3. Crystal diodes.
D plus numbers are often used for crystal diodes in circuits, such as: D5 represents a diode of 5.
1. Function: The main feature of the diode is unidirectional conductivity, that is, under the action of forward voltage, the conduction resistance is very small; under the action of reverse voltage, the conduction resistance is very large or infinite. Due to the above characteristics of diodes, cordless phones are often used in circuits such as rectification, isolation, voltage regulation, polarity protection, coding control, FM modulation, and noise suppression.
The crystal diodes used in telephones can be divided into: rectifier diodes (such as 1N4004). Isolation diodes (such as 1N4148). Schottky diodes (such as BAT85). Light emitting diodes. Zener diodes, etc.
2. Identification method: The identification of diodes is very simple. The N pole (negative pole) of the low-power diode is mainly marked with a color circle on the appearance of the diode. Some diodes also use a special symbol for diodes to denote either P-pole (positive pole) or N-pole (negative pole), and use symbols labeled P and N to determine diode polarity. The positive and negative poles of the light-emitting diode can be identified from the length of the pins, the long pins are positive and the short pins are negative.
3. Test precautions: When measuring the diode with a digital multimeter, the red test lead is connected to the positive electrode of the diode, and the black test lead is connected to the negative electrode of the diode. The resistance value measured at this time is the forward on-resistance value of the diode, which is exactly the opposite of the connection method of the test lead of the pointer multimeter.
Fourth, the Zener diode.
ZD plus numbers are often used for Zener diodes in circuits, such as: ZD5 represents a Zener tube of 5.
1. The voltage regulation principle of the Zener diode: The characteristic of the Zener diode is that the voltage at both ends remains basically unchanged. In this way, when the Zener tube is connected to the circuit, if the power supply voltage fluctuates or other reasons cause the voltage at various points in the circuit to change, the voltage across the load will remain basically unchanged.
5. Inductance
Commonly used in the circuit, L plus a number represents the inductance, such as: L6 represents the 6th inductance.
The inductor coil is an insulated wire wound a certain number of turns on the insulating skeleton.
DC can pass through the coil, and the DC resistance is the resistance of the wire itself, and the voltage drop is very small; when the AC signal passes through the coil, a self-inductive potential will be generated at both ends of the coil. The direction of the self-inductive potential is opposite to that of the external voltage, preventing the passage of AC. Therefore, inductance is characterized by AC through DC resistance. The higher the frequency, the higher the coil impedance. Inductors can form oscillating circuits with capacitors in the circuit.
Inductors generally have direct marking method and color marking method, similar to resistance. For example, brown. black. gold. gold means 1uH (error 5%) inductance.
The basic units of inductance are: Henry (H) conversion units are: 1H=103mH=106uH.
Well, the above is the basic knowledge of electronic components, have you learned it?