(Resistance identification and application)
Resistance identification and application of electrical conductors, said of the current obstacles to the role of the resistance, with the symbol R, said unit ohms, kilohms, megohms, respectively Ω, kΩ, MΩ said.
1, resistance type designation:
domestic resistor model consists of four parts (NA-sensitive resistor)
Part I: Main said, with letters, that product’s name. If that resistance R, W, said potentiometer.
Part II: materials, with letters that said what material composition resistors, T-carbon, H-synthetic carbon film, S-organic solid, N-inorganic solid, J-metal film, Y-N membrane, C-deposited film, I-glass glaze film, X-wound.
Part III: Classification, general use numbers that use letters to individual type, indicating what type of product. 1 - Normal, 2 - normal, 3 - UHF, 4 - High Resistance, 5 - high temperature, 6 - Precision, 7 - Precision, 8 - high voltage, 9 - Special, G-high-power, T-adjustable.
Part IV: serial number, with numbers indicate that the different varieties of similar products to differentiate products and performance indicators Dimensions
example: RT 1 1 type ordinary carbon film resistors a1)
2, resistor classification
1, wirewound resistors: Universal wire wound resistor, precision wirewound resistors, high power wirewound resistors, high frequency wound resistor.
2, thin film resistors: carbon film resistors, synthetic carbon film resistors, metal film resistors, metal oxide film resistors, chemical deposition film resistors, glass glaze film resistors , metal nitride film resistor.
3, solid resistors: inorganic synthesis of solid carbon resistors, organic synthesis, solid carbon resistors.
4, sensitive resistors: varistors, thermistors, photosensitive resistors, force sensitive resistors, sensing resistor, humidity sensitive resistor. Third, the main characteristic parameters
1, Nominal Resistance: resistor marked above resistance.
2, allowing error: nominal resistance value and the actual resistance value of the difference with the nominal resistance of said resistance than the percentage of deviation, which indicated that the precision resistors.
permissible error and the precision level of correspondence is as follows:? .5% -0.05,?% -0.1 (or 00 ),?%- 0.2 (or 0 ),?%- Ⅰ level ,? 0% - Ⅱ grade,? 0% - Ⅲ grade
3, rated power: in the normal atmospheric pressure 90-106.6KPa and the ambient temperature of -55 ℃ ~ +70 ℃ conditions, the resistors long-term work permit maximum power dissipation.
wirewound resistors rated series for the (W): 1 / 20, 1 / 8, 1 / 4, 1 / 2, 1,2,4,8,10,16 , 25,40,50,75,100,150,250,500
non-wirewound resistor rated power series for the (W): 1 / 20, 1 / 8, 1 / 4,1 / 2,1,2,5,10,25,50,100
4, Rated voltage: the resistance and rated voltage of the power converter.
5, the maximum operating voltage: the maximum allowable continuous operating voltage. In the low-pressure work, the maximum operating voltage is low.
6, temperature coefficient: 1 ℃ temperature change caused by each of the relative change in resistance value. The smaller the temperature coefficient, the better the stability of resistance. Resistance increases with increasing temperature for the positive temperature coefficient, and vice versa for a negative temperature coefficient.
7, the aging factor: resistor load in the long-term power rating, the percentage of relative changes in resistance, it is said that the parameters of the length of resistor life.
8, voltage coefficient: the specified voltage range, voltage per 1 V change, the relative variation of resistors.
9, noise: generated in the resistor in an irregular voltage fluctuations, including thermal noise and current noise of two parts, thermal noise is due to the internal conductor of electronic freedom of movement of irregular , so that any two points conductor voltage conjugation.
4, resistor marked resistance method
1, direct standard method: The numbers and unit symbols marked on the resistor surface resistance, which allows direct use of error expressed as a percentage, if not inject bias resistor, then both? 0%.
2, symbols Method: Arabic numerals, and symbols with a regular combination of both, said nominal resistance, the allowable deviation also use text symbols. Symbol in front of an integer number of said resistance, the latter figure in turn, said first and second decimal places decimal resistance resistance.
symbols that allow the error symbols DFGJKM
tolerance? .5%?%?%?%? 0%? 0%
3, digital Method: In the resistor with a nominal value of the three signs that the digital method. Digital left to right, first, two for the RMS, the third for the index, the number zero, units in Europe. Deviation usually written symbols.
4, color standard method: with different colors or point marked on the resistor surface, nominal resistance and tolerance. Most of the foreign resistance method using color.
black -0, -1 Brown, -2 Red, -3 Orange, -4 Yellow, -5 Green, -6 Blue, -7 Violet, -8 Gray, -9 White gold -?%, Silver - ? 0%, colorless -? 0%
when the resistance of tetracycline, the last part will be for the gold or silver, for the first two digits, the third number for the involution, the fourth for the deviation . When the resistance rings, the last link with the larger distance in front of City of Victoria. The first three digits, the fourth number for the involution, the fifth for the deviation.
Five common resistor
1, potentiometer
potentiometer is a mechanical and electrical components, his brush in the resistor body by sliding, get into a certain relationship with the brush shift the output voltage.
1.1
synthetic carbon film potentiometer resistance through the grinding body is carbon black, graphite, quartz and other material coating on the surface of the substrate is made, the process is simple, is the application The most widely potentiometer. Features differentiate the high wear resistance force, longer life expectancy. Drawback is that current noise, nonlinear, resistant to moisture and resistance stability of difference.
1.2
organic solid organic solid potentiometer potentiometer potentiometer is a new type, which is heated plastic pressure method, the organic insulation resistance of powder in the groove pressure . Solid organic carbon potentiometers potentiometer, compared with a good heat resistance, power, reliability, wear resistance advantages. But the temperature coefficient, dynamic noise, to bear tide poor performance, manufacturing process complexity, resistance less precision. In small, high reliability, high wear resistance of electronic equipment as well as AC and DC circuit for regulating voltage and current.
1.3 potentiometer
uranium metal glass screen printing method in accordance with certain graphics, the metal resistance coating slurry of uranium glass ceramic substrate, sintered at high temperature. Features are: wide range of resistance, good heat resistance, strength overload capacity, resistant to moisture, wear and so well, is a promising species potentiometer, drawback is that a large contact resistance and current noise.
1.4
winding wound potentiometer potentiometer is Hong copper or nickel chromium alloy wire as a resistance body, and put it around the insulation made of skeleton. Wound potentiometer is characterized by small contact resistance, high accuracy, temperature coefficient, the drawback is poor resolution, low resistance, high-frequency characteristics of difference. Mainly used as divider, rheostat, equipment and work in zero points.
1.5 Metal Film Potentiometers
metal film potentiometers resistors can be alloy film, metal oxide film, metal foil, etc. were formed. Characteristics differentiate high strength, high temperature, low temperature coefficient, dynamic noise, smooth and good.
1.6
conductive plastic potentiometer with a special process to DAP (c fat thin phthalate) resistor paste cover the insulation body, the heat resistance of polymer into a film, or DAP resistance to pressure in the insulation powder thermoplastic matrix to form the solid body cavity as resistors. Characteristics: smooth, excellent ability to differentiate between good wear resistance, long life, dynamic noise, high reliability, resistance to chemical corrosion. Devices for space, missiles, aircraft radar antenna servo system.
1.7
with switch potentiometer switch potentiometer with rotary, push-pull switch potentiometer, push, switch-type potentiometer
1.8
preset potentiometers preset potentiometers in the circuit, once and tested, using wax to seal adjustment position, in general no longer be adjusted.
1.9 Slide potentiometers
change by way of direct sliding resistance.
1.10
double potentiometers have different shaft and coaxial double double potentiometer potentiometer
1.11 non-contact potentiometer
; non-contact potentiometer to eliminate the mechanical contact, long life, high reliability, sub photoelectric potentiometer, magnetic-type potentiometer.
2, Solid carbon resistors
carbon particles with a strong conductive material, filler and binder blend of a physical resistor.
characteristics: low price, but the resistance error, the noise voltage is large, poor stability, there is less use.
3, wound resistor with high resistance alloy
skeleton made of insulated wire on the outside of the glaze coated with heat insulation or insulating paint.
winding resistance has a low temperature coefficient of resistance and high precision, good stability, heat resistant, mainly used to do precision high-power resistors, high frequency performance disadvantage is poor, a large time constant.
4, thin film resistors
evaporation method with a certain resistance material deposited on the surface made of insulating material. Mainly as follows:
4.1 crystalline carbon film resistors
to carbon deposition in the skeleton made of ceramic rods. Carbon film resistors, low cost, stable performance, wide range of resistance, temperature coefficient and low voltage coefficient, is the most widely used resistor.
4.2 metal film resistors.
vacuum evaporation method to alloy deposited on the surface of ceramic rod frame.
metal film resistor carbon film resistor than high precision, good stability, noise, temperature coefficient. In the instrumentation and communications equipment are widely used.
4.3
metal oxide film resistor deposited on a layer of insulating metal oxide rods. Oxide because of its own that is so high temperature stability, thermal shock load capability.
4.4 Synthesis of conductive composite membrane resistance
the suspension obtained in the matrix coating, and therefore called the film resistance.
presented because of its granular structure of the conductive layer, so its big noise, low precision of him manufacture high pressure, high impedance, small resistor.
5, uranium metal glass resistor
uranium metal powder and glass powder mixed with screen printing printed on the substrate.
resistant to moisture, temperature, temperature coefficient is small, mainly used in thick film circuit.
6, Chip Resistor SMT
metallic glass sheet resistance is a form of uranium resistance, the resistance of his body is highly reliable series of glass-ruthenium uranium material through high temperature sintering and into the electrode paste with silver palladium alloy. Small size, high accuracy, good stability and its components for the sheet, so high-frequency performance is good.
7, sensitive resistance means resistance
sensitive device characteristics with temperature, humidity, light, gas, magnetic field, the role of pressure-sensitive resistor.
sensitive resistor symbol is the symbol of resistance in general add a slash mark in the sensitive side type of resistance, such as: t. v and so on.
7.1, varistor
mainly silicon carbide and zinc oxide varistor, zinc oxide has more good features.
7.2, humidity resistance
by the sense of wet layer, electrode, insulator composition, humidity resistance include lithium chloride humidity resistance, humidity resistance of carbon, oxides humidity resistance. Lithium chloride humidity resistance and resistance decreased with increased humidity and disadvantages for the test range of small, poor repeatability characteristics, affected by temperature large. Disadvantage for the low carbon humidity resistance low sensitivity, resistance affected by temperature, large, by the aging characteristics, and less use.
oxides humidity resistance performance than superior, long-term use, the temperature effect is small, and humidity resistance is linear. With tin oxide, nickel ferrite, and other materials.
7.3, photosensitive resistance
photosensitive resistance is the conductivity changes with the change of light according to their means of electronic components, when a substance by the light, the carrier concentration increases, thus increased conductivity, which is photoconductive effect.
7.4, using some of the semiconductor gas sensing resistor
occurred after absorption of a gas made of oxidation-reduction reaction, the main component of metal oxides, the main varieties are: metal-oxide gas Min resistance, mixed oxide gas sensing resistor, such as ceramic sensing resistor.
7.5, force sensitive resistors
force sensitive resistor is a resistance value varies with the pressure resistance, known as the piezoelectric resistor abroad. The so-called pressure resistance effect that the resistivity of the semiconductor material changes with the change of mechanical stress effects. Torque meter can be made into a variety of semiconductor microphones, pressure sensors. The main products are silicon force-sensitive resistors, selenium, tellurium co-Jin Limin resistors, relatively speaking, alloy resistor has a higher sensitivity.