Commonly used components analysis table

First, the capacitor

1, the capacitor in the circuit is generally used "C" plus digital (such as C13 said the number 13 of the capacitor). Capacitance is composed of two pieces of metal film close to the middle of the insulating material separated by the composition of the components. The characteristics of the capacitor are mainly DC-AC.

Capacitive capacity is the size that can store the size of the energy, the capacitance of the AC signal is called the capacitive reactance, which is the frequency of AC signals and capacitance.

Capacitance capacitance, ceramic capacitors, chip capacitors, monolithic capacitors, tantalum capacitors and polyester capacitors, etc., are the main types of capacitors used in telephones, such as electrolytic capacitors, ceramic capacitors, chip capacitors, monolithic capacitors, tantalum capacitors, and polyester capacitors. The

2, identification methods: capacitance identification method and resistance identification method is basically the same, sub-straight standard method, color standard method and the number of standard method 3. The basic unit of capacitance is denoted by Faraday (F), and other units are: mF, uF, nF, and pF. Of which: 1 Farah = 103 cents = 106 microfarads = 109 na = 1012 Pico

Large capacity of the capacitance of its capacitance value directly marked on the capacitor, such as 10 uF / 16V

Capacitance The capacitance value is expressed in letters or numerals on the capacitor

Letter representation: 1m = 1000 uF 1P2 = 1.2PF 1n = 1000PF

Numeric notation: generally use three digits to represent the size of the capacity, the first two digits indicate the effective number, the third digit is the magnification.

For example, 102 indicates 10 × 102PF = 1000PF 224 represents 22 × 104PF = 0.22 uF

3, the capacitance capacity error table

Symbol F G J K L M

Tolerance ± 1% ± 2% ± 5% ± 10% ± 15% ± 20%

Such as: a ceramic capacitor 104J said capacity of 0. 1 uF, the error is ± 5%.

Second, the resistance

Resistance in the circuit with "R" plus the number that, such as: R1 said the number 1 resistance resistor in the circuit's main role: shunt, current limiting, partial pressure, bias and so on.

1, parameter identification: the unit of resistance for the ohm (Ω), the rate units are: kilohms (KΩ), megger (MΩ) and other conversion

The method is: 1 megohm = 1000 kΩ = 1000000 euro

Resistance of the parameter labeling method has three kinds, namely, straight standard method, color standard method and the number of standard method.

First, the number of standard method is mainly used for small size of the chip circuit, such as:

472 represents 47 × 100Ω (i.e., 4.7K), and 104 represents 100K

B, color ring labeling method to use the most, for example, the following:

Four-color ring resistance Five-color ring resistance (precision resistance)

2, the resistance of the color position and magnification relationship as shown in the following table:

Color Effective Digital Magnification Allowable Deviation (%)

Silver / x0.01 ± 10

Gold / x0.1 ± 5

Black 0 +0 /

Brown 1 × 10 ± 1

Red 2 x 100 ± 2

Orange 3 x1000 /

Yellow 4 x10000 /

Green 5 x100000 ± 0.5

Blue 6 x1000000 ± 0.2

Purple 7 x10000000 ± 0.1

Gray 8 x 100000000 /

White 9 x 1000000000 /

Third, the inductance

Inductors used in the circuit "L" plus digital representation, such as:. L6 that the number of 6 inductance inductance coil is insulated wire in the insulated skeleton on a certain number of turns made through the coil, the DC resistance is the resistance of the wire itself, the voltage drop is very small; when the AC signal through the coil , The coil ends will produce self-inductance electromotive force, self-induced electromotive force in the direction of the opposite direction with the applied voltage, hinder the passage of AC, so the characteristics of the inductor is through the DC resistance of the exchange, the higher the frequency, the larger the coil impedance in the circuit Can be composed of capacitance and oscillation circuit inductance generally have a straight standard method and color standard method, color standard method and resistance similar to:. Brown, black, gold, gold that 1uH (error 5%) of the inductor. The basic unit of inductance is: Hen (H) conversion units are: 1H = 103mH = 106uH.

Fourth, the crystal diode

Crystal diodes in the circuit commonly used "D" plus digital, such as: D5 said the number 5 of the diode.

1, the role: the main characteristics of the diode is one-way conductivity, that is, under the action of the forward voltage, the on-resistance is very small; and in the reverse voltage under the conduction resistance is great or infinity is because the diode has the above characteristics , Cordless telephones often used in the rectifier, isolation, regulation, polarity protection, coding control, FM modulation and squelch and other circuits used in the telephone crystal diode can be divided into: rectifier diodes (such as 1N4004) , Isolation diodes (such as 1N4148), Schottky diodes (such as BAT85), light-emitting diodes, Zener diodes and so on.

2, the identification method: the identification of the diode is very simple, low-power diode Ñ pole (negative), in the diode appearance of most of the use of a color circle marked out, some diodes also use diode-specific symbols to express P pole (positive) or Ñ (Negative), there are signs using the symbol "P", "N" to determine the polarity of the diode. The positive and negative poles of the LEDs can be learned from the length of the pins

Do not, long feet are positive, short feet are negative.

3, test Note: With a digital multimeter to test the diode, the red pen then the diode cathode, black pen then diode negative, this time the measured resistance is the diode forward resistance, which is the pointer type Multimeter table pen connection just the opposite.

4, commonly used 1N4000 series diode voltage comparison are as follows:

Model 1N4001 1N4002 1N4003 1N4004 1N4005 1N4006 1N4007

Pressure (V) 50 100 200 400 600 800 1000

Current (A) is 1

Fifth, the regulator diode

Zener diode in the circuit commonly used "ZD" plus digital, such as: ZD5 said the number of 5 regulator tube.

1, Zener diode regulator principle: Zener diode is characterized by breakdown, the voltage at both ends of the basic remains the same, when the regulator connected to the circuit after the power supply voltage fluctuations, or other reasons Causing the voltage changes in the circuit, the voltage across the load will remain essentially unchanged.

2, fault characteristics: voltage regulator diode fault mainly in the open circuit, short circuit and regulator value instability in these three kinds of failure, the former failure to show the power supply voltage increases; after the two kinds of fault performance for the power supply voltage becomes low To zero volts or output is unstable.

Commonly used Zener diode model and regulator values as follows:

Model 1N4728 1N4729 1N4730 1N4732 1N4733 1N4734 1N4735 1N4744 1N4750 1N4751

1N4761

Regulated voltage 3.3V 3.6V 3.9V 4.7V 5.1V 5.6V 6.2V 15V 27V 30V 75V

Six, varactor diode

Variable diodes are based on ordinary diode internal "PN junction" of the junction capacitance with the addition of anti-voltage changes in the principle of this principle designed specifically for a special diode varactor in the cordless telephone mainly used for mobile phones or landline High-frequency modulation circuit, to achieve low-frequency signal modulation to the high-frequency signal, and launched out. In the working state, the varactor diode modulation voltage is generally applied to the negative electrode, so that the capacitance of the internal junction capacitance of the varactor varies with the modulation voltage.

Varactor diode failure, mainly for the leakage or performance deterioration:

(1) when the phenomenon of leakage occurs, the high-frequency modulation circuit will not work or modulation performance deterioration.

(2) When the variable capacity is deteriorated, the operation of the high-frequency modulation circuit is unstable, and the modulated high-frequency signal is transmitted to the opposite side to be distorted by the other party.

When one of the above conditions occurs, the same type of varactor should be replaced.

Seven, crystal transistor

Crystal transistor in the circuit commonly used "Q" plus digital, such as: Q17 said the number 17 of the transistor.

1, features: crystal transistor (referred to as transistor) is a two internal PN junction, and has the ability to amplify the special device it is divided into NPN type and PNP type two types of these two types of transistors from the working characteristics can make up each other, The so-called OTL circuit is the PNP type and NPN type with the use of telephone commonly used PNP-type transistor: A92, 9015 and other models; NPN-type transistor: A42,9014,9018,9013,9012 and other models.

2, the crystal transistor is mainly used for amplification circuit in the amplification effect, there are three common circuit in the connection. In order to facilitate comparison, the transistor three circuit has the characteristics of the following table, for your reference.

Common pole circuit (common pole output device)

Input impedance (hundreds of Europe - several thousand euros) large (tens of thousands of euros or more) small (several Europe - several tens of Europe)

(Several tens of thousands of euros)

Voltage magnification size (less than 1 and close to 1) large

(A few) small (less than 1 and close to 1)

Power magnification (about 30 - 40 decibels) small (about 10 decibels) (about 15 - 20 decibels)

Application of multi-stage amplifier intermediate level, low frequency amplification input stage, output stage or for impedance matching with high frequency or wide band circuit and

Constant current source circuit

8, field effect transistor amplifier

1, the field effect transistor has a high input impedance and low noise and other advantages, which is also widely used in a variety of electronic equipment. Especially the use of FET to do the entire electronic equipment input level, you can get the general transistor is difficult to achieve the performance.

2, the field effect is divided into knot type and insulated grid two categories, the control principle is the same.

3, field effect transistor and transistor comparison

(1) the field effect transistor is the voltage control element, and the transistor is the current control element only allows less current from the signal source, the field effect transistor should be used; and the signal voltage is low, allowing the signal from the source More current conditions, should use the transistor.

(2) The field effect transistor is the use of the majority carrier conduction, so called the unipolar type device, while the transistor is that there are a large number of carriers, also using minority carrier conduction. Known as bipolar devices.

(3) Some of the field effect of the source and drain can be used interchangeably, the gate voltage can also be negative, flexibility better than the transistor.

(4) field effect can work in very small current and very low voltage conditions, and its manufacturing process can be very convenient to integrate a lot of FET on a piece of silicon, so the FET in large-scale integrated circuits Has been widely used.