Classification by volt ampere characteristics
For most conductors, the resistance
remains almost constant at a certain temperature. This kind of resistance
is called linear resistance. The resistance of some materials obviously changes with the current (or voltage), and its V-A characteristic is a curve. This kind of resistance
is called nonlinear resistance. Under the action of a given voltage (or current), the ratio of voltage to current is the static resistance at the working point, and the slope on the V-A characteristic curve is the dynamic resistance. The expression of nonlinear resistance characteristics is complex, but these nonlinear relations have been widely used in electronic circuits
Classification by material
1.The wire wound resistor
is formed by winding the resistance wire. The resistor is made of high resistance alloy wire wound on the insulation skeleton, and the outside is coated with heat-resistant glaze insulation layer or insulating paint. Winding resistance has low temperature coefficient, high resistance accuracy, good stability, heat resistance and corrosion resistance. It is mainly used as precision high-power resistance. Its disadvantages are poor high-frequency performance and large time constant.
2.Carbon synthetic resistor is made of carbon and synthetic plastic.
3.The carbon film resistor is made by plating a layer of carbon on the ceramic tube and depositing the crystalline carbon on the ceramic rod skeleton. Carbon film resistor is the most widely used resistor at present because of its low cost, stable performance, wide resistance range and low temperature coefficient and voltage coefficient.
4. The metal film resistor is formed by plating a layer of metal on the ceramic tube, and the alloy material is evaporated on the surface of the ceramic rod skeleton by vacuum evaporation.
Compared with carbon film resistance, metal film resistance has the advantages of high precision, good stability, low noise and low temperature coefficient. It is widely used in instruments and communication equipment.
5. The metal oxide film resistor is formed by plating a layer of tin oxide on the porcelain tube and depositing a layer of metal oxide on the insulating rod. Because it is an oxide itself, it is stable at high temperature, resistant to heat shock and strong load capacity. According to its purpose, it has general purpose, precision, high frequency, high voltage, high resistance, high power and resistance network.