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46483 2008 年 01 月 13 日 01:24 Reading (loading. ..) Comments (0) Category: Personal Diary
First, the resistance of resistors in the circuit using
Resistance in the circuit for the shunt main role, the current limit, voltage, bias and so on.
1, parameter identification: resistance in ohms (Ω), rate units are: kilohms (KΩ), megohm (MΩ) and so on. Conversion is: 1 Mohm = 1000 = 1000000 EU
kilohms resistance Tagging There are 3 parameters, namely, direct standard method, method and digital color standard method.
a, the number of such standard method is mainly used for small size of the circuit chip, such as: 472, said 47 × 100Ω (ie 4.7K); 104 indicates 100K
b, color ring labeling method most used are for example as follows: four-color colored ring ring resistance resistor (precision resistance)
2, resistance ratio between location and color as follows: color valid number ratio tolerance (%)
silver / x0.01 ± 10
gold / x0.1 ± 5
Black 0 +0 /
Brown 1 x10 ± 1
Red 2 x100 ± 2
Orange 3 x1000 /
Yellow 4 x10000 /
5 x100000 ± 0.5
green blue purple 6 x1000000 ± 0.2
7 x10000000 ± 0.1
Gray 8 x100000000 /
White 9 x1000000000 /
Second, the capacitor
1, capacitance in the circuit was used in the Capacitance is close to the two metal films, separated by insulating material which consists of separated components. The properties of capacitors is blocking flow of exchanges. The size of capacitance that can store energy that is the size of capacitor hinder the exchange of signals is called capacitive reactance, it flows and exchange
signal frequency and volume. Capacitive reactance XC = 1/2πf c (f the frequency of AC signal, said, C said capacitance) capacitor commonly used types of phones are electrolytic capacitors, ceramic capacitors, chip capacitors, monolithic capacitors,
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2, identification: Identification of capacitance and resistance identification method is basically the same, sub-standard method until the color standard method and several standard method 3. The basic unit of capacitance with Farah (F), said other units are: mm method (mF), microfarad (uF), mobility method (nF), skin method (pF). Where: 1 = 103 cents Law Farah micro-method = 109 = 106 = 1012 picofarads satisfied law
capacity value of capacitance capacitor capacity directly marked, such as 10 uF/16V
small capacity capacitor capacity value of the capacitor to a letter or number that
letter notation: 1m = 1000 uF 1P2 = 1.2PF 1n = 1000PF
numerical representation: the capacity for general use, said the size of three digits, said first two digits , the third digit is the magnification.
such as: 102, said 10 × 102PF = 1000PF 224, said 22 × 104PF = 0.22 uF
3, Table
capacitance symbol FGJKLM
error tolerance ± 1% ± 2% ± 5% ± 10 % ± 15% ± 20%. such as: a ceramic capacitor that capacity for the 104J 0. 1 uF, error is ± 5%.
Third, the crystal diode
crystal diode circuits used in
1, role: The main characteristics of the diode is a one-way conductivity, which is under the effect of the forward voltage, resistance is very small; in reverse voltage resistance under maximum or infinite. Because the diode has the characteristics of cordless telephones often use it in the rectifier,
handbags online cheap, isolation, voltage, polarity protection, coding control, frequency modulation and suppression and other circuits.
telephone in accordance with the role of the crystal diode can be divided into: rectifier diode (eg 1N4004), isolation diode (eg 1N4148), Schottky diode (such as BAT85), light emitting diodes, voltage regulator diodes.
2, identification: Identification of the diode is very simple, low-power diode N pole (negative), most of the diode appearance marked by a color ring out, and some special symbols diode diode is also used to represent the P pole (positive) or N pole (negative), there is also symbol for the Positive and negative light-emitting diodes from pin
not know the length of long leg is positive,
paul smith wallet, the short leg is negative.
3, test Note: use the digital multimeter to test diodes, the red pen then the positive terminal of the diode, the black pen then the negative terminal of the diode, when the measured resistance is the resistance of the diode is forward, which Analog Multimeter table with the pen connection just the opposite.
4, used the 1N4000 series diode voltage is as follows:
Model 1N4001 1N4002 1N4003 1N4004 1N4005 1N4006 1N4007
voltage (V) 50 100 200 400 600 800 1000
Current (A) are 1
IV
regulator diode zener diodes used in the circuit 1, the voltage regulator diode principle: that the breakdown voltage characteristics of diode,
burberry bags, its voltage across essentially unchanged. Thus, when access to the circuit after the regulator, if the supply voltage fluctuation, or other points in the circuit causes power
pressure changes, the voltage across the load will be basically unchanged.
2, fault characteristics: Zener diode fault mainly in the open, short and unstable voltage values. 3 failures in this,
paul smith uk, the first of a failure to show increased supply voltage; failure after 2 to low performance of the supply voltage to zero volts or output instability.
common voltage regulator diode model and values as follows: Type 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
V.
inductor used in the circuit inductance inductor that number is 6. Inductance coil is insulated wire around the insulation of the skeleton made of a certain number of laps. DC through the coil, DC resistance is the resistance wire itself, a small pressure drop; when the AC signal through the coil, the coil inductance force will be generated, self force in the direction opposite the direction of the applied voltage and hinder the exchange of passed, so the characteristics of the inductor DC resistance is through communication, the higher the frequency, the greater the coil impedance. Inductor and capacitor in the circuit can be composed of oscillation
circuit.
inductors generally have direct standard method and color standard method, standard method and the resistance of a similar color. Such as: brown, black, gold, gold that 1uH (error 5%) of the inductor. The basic unit of inductance
: Henry (H) conversion units: 1H = 103mH = 106uH.
VI
varactor varactor diode in accordance with ordinary internal Varactor is mainly used in cordless phone base in the mobile phone or high-frequency modulation circuit,
handbags online, low frequency to high frequency modulated signal, and launch out. In the working state, the varactor modulation voltage is generally added to the anode, so that the internal junction varactor capacitance changes with the modulation voltage changes.
varactor failure, mainly for the leakage or performance variation:
(1) leakage phenomenon occurs when the frequency modulation circuit will not work or modulation performance deteriorated.
(2) modulation in poor performance, the high frequency modulation circuit of job insecurity, the modulated high frequency signal is sent to each other after the other receivers distortion. One of the above circumstances, it should be replaced with the type of varactor diodes.
seven
transistor transistor commonly used in the circuit
1, features: transistor (the transistor) is the interior includes two PN junction, and a special device with amplification. NPN and PNP type is sub-type of two types, both types of transistor characteristics from the work on each other to make up the so-called OTL circuit is on the tube by the PNP type and NPN type paired. Telephone in the PNP-type transistors are commonly used: A92, 9015 and other models; NPN-type transistor are: A42, 9014,9018,9013,9012 models.
2, transistor amplifier is mainly used for amplification played in three common circuit connection. For comparison, three connection transistor circuit with the characteristics listed in the table below, for your reference. Name of the common emitter circuit common collector circuit (emitter)
common base input impedance of the circuit (a few hundred ohms to several thousand Euro) Large (more than tens of thousands of Euro) small (a few European ~ dozens of Europe)
output impedance (~ tens of thousands of thousands of Europe Europe) small (a few ohms to tens of Europe) large (tens of thousands of ohms to hundreds of thousands of Euro)
voltage magnification size (less than 1 and close to 1) a large current amplification factor
large (tens of) large (dozens) of small (less than 1 and close to 1)
power magnification of large (about 30 40 dB) small (about 10 dB) in (about 15 ~ 20 dB)
difference between a good high frequency characteristics of multi-stage amplifier applications
intermediate frequency amplification input, output, or for impedance matching high frequency or broadband circuit and constant current source circuit
eight field-effect transistor amplifier
1, field-effect transistors with high input impedance and low noise, etc., which are also widely used in various electronic devices. In particular, effective use of electronic equipment to do the whole tube input stage, can be difficult to achieve the general performance of the transistor.
2, junction field effect transistor and insulated gate is divided into two major categories, the control principle is the same.
3, FET transistors compared with
(1) field effect transistor is the voltage control device, while the transistor is a current control device. The only source to take less from the current case, the FET should be used; in the signal voltage is low, but also allows more current from the source under the conditions of access should be used in transistors.
(2) FET is the use of majority carrier conduction, so called unipolar device, the transistor is that a majority carrier, also used minority carrier conduction. Known as bipolar devices.
(3) some of the FET source and drain can be used interchangeably, the gate voltage can be positive or negative, flexibility, better than transistors.
(4) FET in a very small current and low voltage conditions, work, and its manufacturing process can be easily integrated into many a piece of silicon FET, so FET large-scale IC has been widely used.
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