【 Weak current College 】 resistor designation, resistors classification, main characteristics of the parameters, the resistance of the marks, common resistors, resistor 】

Resistance

Conductors on current impediment that resistance, expressed by the symbol R units of ohm, kilohms, megohm, respectively Ω, k Ω Ω, M.
First, the resistance of a model named method:
Homemade resistors model consists of four components (does not apply in sensitive resistor)
Part i: the primary that letter that represents the product name. If r = resistance, W represents a potentiometer.
Part II: material, letter, indicating that the resistance of what material composition, T-carbon film, H-synthetic organic carbon, black, S-N-inorganic solid, J-metal film, Y-C-nitride film and deposition films, I-glass glaze film, X-wire wound.
Part three: general classification, a number, the individual type of letter that represents the type of product. 1-normal, normal, 2-3-UHF, 4-high-temperature-resistance, 5-, 6-precision, high precision, 7-8-9-special high pressure, and G-high power, T-adjustable.
Fourth part: serial number, a number that represents the class of different varieties to differentiate the product dimension, and performance indicators, etc.
For example: R T 1 1-ordinary carbon film resistors a1} 2 resistors classification
1. wire-wound resistors: General-purpose wire wound resistors, precision wire wound resistors, power wire wound resistors, RF wire wound resistors.
2 film resistor: carbon film resistors, synthesis of carbon film resistors, resistor metal film, metal oxide film resistors, chemical deposition film resistors, glass glaze film resistors, metal nitride film resistors.
3. solid resistor: inorganic synthesis of solid carbon resistors, organic solid carbon resistor.
4. sensitive resistor: pressure-sensitive resistors, Thermistors, photosensitive, force sensitive resistor, gas sensing resistors, humidity sensitive resistor. III. main characteristics
1. nominal resistance: resistor above marked resistance.
2, allows error: nominal resistance and the actual resistance of difference with nominal resistance ratio percentage that deviation, it indicates that the resistance resistors for accuracy.
Permissible error and precision grade correspondence: ± 0.5%-0.05, ± 1%-0.1 (or 00), ± 2%-0.2 (or 0), ± 5%-Ⅰ, Ⅱ ± 10%-20%, ±-grade ⅲ
3. rated power: at normal atmospheric pressure 90-106.6KPa and environment temperature:-55 ° c ~ + 70 ° c, the resistors long-term work the allowed maximum power dissipation.
Wire-wound resistors rated power series (W): 1/20, 1/8, 1/4, 1/2, 1, 2, 4, 8, 10, 16, 25, 40, 50, 75, 100, 150, 250, 500
Nonlinear wound resistors rated power series (W): 1/20, 1/8, 1/4, 1/2, 1, 2, 5, 10, 25, 50, 100
4. rated voltage: from resistance and rated power conversion out of voltage.
5, maximum working voltage: maximum continuous operating voltage. When working in low atmospheric pressure, maximum operating voltage is low.
6. temperature coefficient: temperature 1 ° c per change resulting from the resistance values of relative change. Temperature coefficient of resistance is smaller, the better stability. Resistance with temperature but increased for positive temperature coefficient, and conversely a negative temperature coefficient.
7, aging coefficient: resistors in long-term load rating, the resistance percentages relative change, it is the length of the resistors life.
8, voltage coefficient: the voltage range, the voltage every variation 1 volt, the amount of relative change resistors.
9. noise: from resistors of irregular voltage fluctuations, including thermal noise and current noise, thermal noise is irregular because the conductor internal electronic freedom movement, the conductor any two points in irregular changes. 4. the resistance of the marking methods for resistors
1. direct standard method: the number and unit symbols in resistor surface marked resistance, its allowable error of direct use of percentage that if the resistance is not note deviation, are ± 20%.
2, letter symbols: symbol text with Arabic numbers and a combination of both to represent nominal resistance, its allowable deviation also used text symbol. Symbol preceding digit integer resistance, the numbers following the order represents the first decimal resistance and the resistance in the second decimal.
Allows error text symbols
Text symbol D F G M J K
Tolerances ± 0.5% ± 1% ± 2% ± 5% ± 10% ± 20%
3. digital method: resistors with three digital represents the nominal value of the flag. Digital from left to right, first and second place as a valid value, the third position for the index, i.e. the number of zero bits '. Deviation usually uses the text symbol.
4, color standard method: the belt of a different color, or point mark in resistor surface nominal resistance and tolerance. Most foreign resistance using color-coding method.
Black-, brown-red-1, 2, 3, orange-yellow-green-4, 5, blue-violet-6, 7, ash-8, white-9, Gold-± 5%, silver-± 10%, 20% transparent colorless-±
When the resistance for the fourth time, the last part will be gold or silver, the first two digits of the digits, the first three digits of the number of fourth powers, as errors. When the resistance of five rings, the last ring and ring distance larger front. First three digits of the digits, the first four digits of the number of powers, the fifth digits of the deviation. 5. common resistors
1, potentiometer
Potentiometer is an electromechanical components, he brushes in resistance on the slide, and brush displacement into certain relations of output voltage.
1.1 synthesis carbon film potentiometer
Resistance of the body is lapped black carbon, graphite, quartz and other materials for coating to the substrate, the process is simple, is the most widely potentiometer. Features a resolution of high wear resistance, long service life. The disadvantage is that current noise, nonlinearOf moisture resistance and the resistance of the poor stability.
1.2 organic solid potentiometer
Organic solid potentiometeris a new type potentiometers, it is a method of heating plastic pressure, resistance to organic powder pressure in the notches on the insulator. Organic solid potentiometers and carbon film resistor has a good heat resistance, high power, high reliability, good wear resistance. But the temperature coefficient of large, dynamic noise, poor resistance to humidity, complex manufacturing process, the resistance of the poor precision. In miniaturization, high reliability, high wear resistance of electronic equipment, as well as AC, DC circuit used for the adjustment of voltage and current.
1.3 metal glass uranium potentiometer
Use screen printing method in accordance with certain graphics, metallic glass uranium resistor paste coating in ceramic substrate, high-temperature sintering. Characteristics: wide resistance range, good heat resistance, overload capacity, high tide, wear, etc., are all very well, is very promising potentiometer varieties, the disadvantage is that contact resistance and current noise.
1.4 wound potentiometer
Wound potentiometer is Kang copper wire or NI-CR alloy wire as resistance, and turned it around in insulated skeleton. Wound potentiometer is characterized by low contact resistance and high precision, low temperature coefficient, the drawback is to distinguish the resistance is low, low, high-frequency characteristics of the poor. Mainly used as a divider, rheostat, instruments and work in the zero point.
1.5 metal film resistor
Metal membrane potentiometer resistors body can consist of alloy film, metal oxide film, metal foil, respectively. Features high resolution power, heat-resistant, temperature coefficient is small, dynamic noise small, smooth and good.
1.6 conductive plastic potentiometers
Use special techniques to DAP (phthalate dilute acrylic ester) resistor paste clad in insulated body, heating aggregates into resistance membrane, or DAP resistance powder thermoplastic insulating substrate of pressure in theform of a solid Groove as resistance. Characteristics: smooth, high power superior wear resistance, long life, dynamic noise small, high reliability, excellent resistance to chemical corrosion. For cosmic device, missiles, aircraft and radar antennas of servo system, etc.
1.7 band switch potentiometer
A rotary switch potentiometer, push-pull switch potentiometer, push switch type potentiometers
1.8 pre-adjustable potentiometers
Pre-adjustable potentiometers in circuit, once debugging is good, with wax seal adjustment positions, under normal circumstances no longer regulated.
1.9 straight sliding potentiometer
Use straight sliding way to change the resistance value.
1.10 dual-attached potentiometers
Different shaft dual-attached potentiometers and coaxial dual-attached potentiometers
1.11 contactless potentiometer
Non-contact potentiometer eliminates mechanical contact, long life, high reliability, opto-electronic potentiometer, magnetic-potentiometers, etc.
2. solid carbon resistors
Carbonaceous particles Chuang conductivity material, filler and Binder mixture made of an entity of the resistor.
Characteristics: low prices, but their resistance errors, noise voltage are large, poor stability, is now less used.
3. wound resistors
With high resistance alloy wire wound in insulated skeleton made of coated with heat resistant outside glazing insulation or varnished.
Winding resistance with low temperature resistance coefficient, high precision, good stability, heat resistance and corrosion resistance, mainly used for high-power resistors do precision, the disadvantage is that high-frequency performance, the time constant.
4, thin film resistors
With evaporation method will necessarily resistivity material evaporation from the surface of insulation materials. The major as follows:
4.1 carbon film resistors
The crystalline carbon deposition in ceramic rods skeleton. Carbon film resistors with low cost, stable performance, wide resistance range, temperature coefficient and a low voltage coefficient, is the most widely resistor.
4.2 metal film resistors.
By vacuum evaporation method alloy evaporation from the surface of ceramic rods skeleton.
Metal film resistors than carbon film resistors for high precision, good stability, low noise, temperature coefficient. In instrumentation and communications equipment for use in large quantities.
4.3 metal oxide film resistors
In insulated rod on a layer of metal oxides. Because of its own that is oxides, high temperature stability, resistance to impact, the load capacity.
4.4 synthetic membrane resistance
The conductive composite suspensions coated in the substrate, thus also called paint film resistors.
Because of its conductive layer rendering granular structure, its low noise, precision, mainly with his manufacturing high pressure, high resistance, small resistor.
5, metal glass uranium resistors
The metal powder and mixed uranium powder glass, using screen printing method in the substrate.
Resistance to humidity, high temperature, low temperature coefficient, mainly used in thick film circuit.
6, SMT SMD resistors
Chip resistors are metal glass uranium one form of resistance, his resistance is high reliability of Ruthenium series glass uranium materials after high temperature sintering, electrode with silver-palladium alloy pastes. Small size, high precision, good stability, since it is a chip components, high-frequency performance.
7, sensitive resistor
Sensitive resistance refers to the device properties on temperature, humidity, voltage, light, gas, pressure effects of magnetic field, sensitive resistor.
Sensitive resistor symbol is the symbol of resistance in common with a slash, in and to the type of callout sensitive resistor, such as: t. V.
7.1, varistor
There are silicon carbide and zinc oxide varistor, zinc oxide has more characteristics.
7.2, humidity resistance
The humidity level, electrodes, insulators, humidity resistance include lithium humidity resistance, moisture resistance, carbon oxide humidity resistance. Licl humidity resistance with increased humidity and resistance to reduce the scope for testing, shortcomings, properties of repetitive, affected by temperature. Carbon humidity resistance and low-temperature sensitivity disadvantages, resistance temperature high-impact, the ageing behaviour, less use.
Oxide humidity resistance performance superior, long-term use, small, resistance temperature and humidity variation is linear. A tin oxide, nickel-iron salts, and other materials.
7.3,-
PhotosensitiveResistance is the conductivity as light t overload of changes of electronic components, when a substance is light, carrier concentration increase thereby increasing electrical conductivity, photoconductive effect.
7.4, gas resistance
Take advantage of some semiconductor absorption occurs after a gas redox reactions, the main ingredient is metal oxides, main varieties are: metal oxide gas resistance, composite oxide gas gas sensing resistor resistor, ceramics, etc.
7.5, force sensitive resistor
Force sensitive resistor is a kind of resistance with pressure changes in resistance, overseas known as piezoelectric resistor. The so-called pressure resistance effect that semiconductor materials resistivity with mechanical stress change effect. Formed by the torque meter, semiconductor microphone, pressure sensor, etc. Main varieties are Silicon force sensitive resistor, selenium and tellurium metal force sensitive resistor, relatively speaking, alloy resistor has a higher sensitivity.