I. Resistance
resistance in the circuit using br> 1, parameter
identification:
resistance in ohms (O), magnification units: kilohms (KO), Meg
(MO), etc. Conversion is:
1 megohm = 1000 kilohms = 1 million mark in Europe
resistance method has three parameters , namely, direct standard
method, the color standard method and several standard
method.
a, the number of standard method is mainly used for such a small
volume of the circuit chip, such as:
472 that 47t100O
(ie 4.7K); 104 indicates 100K
b, color ring mark method most used, are some examples: four -color
ring resistors colored ring resistance (precision resistance)
2, resistor color standard position and magnification relations in
the following table:
effective digital zoom allows the color deviation (%)
silver / x0.01 / -10
gold / x0.1 / -5

Black 0 0 /
brown 1×10 / -1
red 2×100 / -2
orange 3×1000 /
< br /> yellow 4×10000 /
green 5×100000 / -0.5
blue 6×1000000 / -0.2 <
purple 7×10000000 /
-0.1 < br />
gray 8×100000000 /
white 9×1000000000 /
Second, the capacitance
1, capacitance in the circuit in general use number of capacitor
13) of the capacitor is two metal film close to the middle
separated by insulating material composed of components of the
capacitor is blocking the main characteristics of the exchange
flow. is that the size of capacitance can store electrical energy,
the capacitor impediment to the AC signal is called capacitance, AC
signal with frequency and capacitance related. capacitive reactance
XC = 1 / 2pfc (f the frequency of said AC signal, C indicates
capacitance)
capacitors commonly used in telephone The types of electrolytic
capacitors, ceramic capacitors, chip capacitors, monolithic
capacitors, tantalum capacitors and polyester capacitors.
2, identification methods: resistive capacitive method of
identification and the identification method is basically the same,
straight standard method, color method and several standard method
three kinds.
the basic unit of capacitance with Farah (F) that other units are:
millifarad (mF), microfarad (uF), sodium Act (nF), pf (pF).
which: 1 farad = 103 mm micro-method = method = 106 109 = 1012 pF
sodium law
capacity of the capacitor capacitance value of its capacity
directly on the mark, such as 10uF/16V
capacity small capacitance value capacitors on its capacity to use
letters or numbers that < br />
letter notation: 1m = 1000uF1P2 = 1.2PF1n = 1000PF
number representation: general capacity with the size of three
digits, the first two that significant figures, third digit is the
magnification.
such as: 102 said 10t102PF = 1000PF224 said 22t104PF = 0.22uF
3, Table
capacitance symbol FGJKLM
error tolerance / -1% / -2% / -5% / -10% / -15% /
-20%
such as: a ceramic capacitor for the 104J that the capacity of
0.1uF, error is / -5%.
Third, the crystal diode
crystal diodes used in the circuit That is the role of the forward
voltage, the resistance is very small; role in the reverse voltage
resistance great or infinite. is because the diode with the above
features, cordless telephones often use it in the rectifier,
isolation, regulator, polarity protection, encoder control, such as
FM modulation and squelch circuits. phone in the use of crystal
diodes can be divided according to function: rectifier diode (eg
1N4004), isolation diode (eg 1N4148), Schottky diodes (eg BAT85),
light-emitting diodes, voltage regulator diode.
2 , identification methods: identification of the diode is very
simple, low-power diode of the N pole (cathode), the appearance of
most of the diode using a color circle marked out, some diode with < br /> the diode very special notation P (positive) or N pole (negative),
there is also the symbol flag to identify the length of long leg is
positive, the short leg is negative. < br />
3, test Note: The digital multimeter to measure the diode, the red
pen then the diode cathode, black pen then the diode cathode,
measured at this time resistance is the resistance of the diode is
forward, which multimeter connected in the table opposite
pen.
4, commonly used 1N4000 series diode voltage are as follows:
Model 1N40011N40021N40031N40041N40051N40061N4007
pressure (V) 501002004006008001000
Current (A) are 1
four, the Zener diode voltage regulator diode in the circuit
commonly used tube.
1, Zener diode voltage regulator principle: Zener diode is
characterized by breakdown, the voltage across it remained
unchanged, so that when access to the circuit after the regulator,
if the power supply voltage as fluctuation, USB
Cables, or other points in the circuit causes the voltage
changes, the voltage across the load will remain largely
unchanged.
2, failure characteristics: Zener diode failure mainly in the open,
short and unstable voltage values ??In these three failures, the
former failed to show increased supply voltage; after the two kinds
of failures showed low voltage output to zero volts or unstable
common voltage regulator diode model and the value of the following
table: Model
1N47281N47291N47301N47321N47331N47341N47351N47441N47501N47511N4761
regulator value 3.3V3.6V3.9V4.7V5.1V5.6V6.2V15V27V30V75V
five inductors in the circuit inductance
commonly used 6 of the inductance.
inductance coil is insulated wire wound on an insulating frame on a
certain number of turns made.
DC through the coil, the DC resistance is the resistance of the
wire itself, the pressure drop is very small; when the exchange
signal through the coil, the coil inductance electromotive force
will be generated at both ends, self-induction electromotive force
in the direction opposite the direction of the applied voltage, by
impeding communication, so the characteristics of the inductor DC
resistance is through the exchange, the higher the frequency the
greater the coil impedance the inductance and capacitance in the
circuit can be composed of the oscillation circuit. inductors
generally have straight color standard method and standard method,
similar to the color standard method with resistance, such as:
brown, black, gold, gold that 1uH (error 5%)
of inductance.
the basic unit of inductance is: Henry (H ) conversion units: 1H =
103mH = 106uH.
six
varactor varactor diode in accordance with ordinary internal The
junction capacitance with the applied reverse voltage can change
this principle specifically designed a special diode. varactor
diode is mainly used in the cordless telephone handset or landline
in the high-frequency modulation circuit, low frequency signal
modulation to the high-frequency signal, MLB
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