Classification and characteristics of resistors and potentiometers
1. Resistor
Resistance, the English name Resistance, usually abbreviated as R, is a basic property of a conductor. The resistance of the conductor to the current is related to the size, material and temperature of the conductor . In fact, “resistance” refers to a property, and the resistance usually referred to in electronic products refers to a component such as a resistor.
The basic unit of resistance is the ohm, represented by the Greek letter “Ω”. The commonly used units for expressing the resistance value of resistors are kilohm (kΩ) and megohm (MΩ). Resistors are the most widely used circuit components, accounting for more than 30% of the total components in electronic equipment, and their quality has a great impact on the stability of the circuit. The main purpose of the resistor is to stabilize and adjust the current and voltage in the circuit , and secondly, it can also be used as a shunt, a voltage divider, and a load that consumes electric energy .
2. Classification of resistors
According to the structure, resistors can be divided into two categories: fixed type and variable type.
(1) Fixed resistor
Due to different manufacturing materials and processes, fixed resistors can be divided into four types: wirewound resistors, solid core resistors, film resistors and sensitive resistors.
Wire-wound resistor RX: There are general-purpose wire-wound resistors, precision wire-wound resistors, high-power wire-wound resistors and high-frequency wire-wound resistors.
Thin film resistors: carbon film resistors RT, synthetic carbon film resistors RH, metal film resistors RJ, metal oxide film resistors RY, chemical deposition film resistors, glass glaze film resistors and metal nitride film resistors.
Solid core resistors: there are inorganic synthetic solid carbon resistors RN and organic synthetic solid carbon resistors RS.
Sensitive resistors: There are piezoresistors, thermistors, photoresistors, force-sensitive resistors, gas-sensitive resistors, and humidity-sensitive resistors.
(2) variable resistor
Variable resistors are divided into sliding wire rheostats and potentiometers, of which the most widely used is the potentiometer.
The potentiometer is a variable resistor with 3 joints, and its resistance value is continuously adjustable within a certain range.
According to the material of the resistor body, it can be divided into two types: film and wire wound. Thin film can be divided into WTX type small carbon film potentiometer, WS type organic solid core
WTH type synthetic carbon film potentiometer, WHJ type precision Synthetic membrane potentiometer and WHD type multi-turn synthetic membrane potentiometer, etc. The code name of the wire wound potentiometer is WX type. Generally, the error of the wire-wound potentiometer is not more than ±10%, and the error of the non-wire-wound potentiometer is not more than ±20%. Its resistance value, error and model are marked on the potentiometer.
potentiometer
According to the movement mode of the adjustment mechanism, it can be divided into two types: rotary type and straight sliding type.
According to the structure, it can be divided into single-connection, multi-connection, with switch , without switch, etc.; the switch forms include rotary type, push-pull type, button type, etc.
According to the purpose, it can be divided into ordinary potentiometers, precision potentiometers, power potentiometers, trimming potentiometers and special potentiometers.
According to the relationship between the resistance value and the rotation angle, it can be divided into linear and nonlinear potentiometers.
features
X type (linear type): commonly used in the focus potentiometer of the oscilloscope and the zero adjustment potentiometer of the multimeter (such as the MF-20 multimeter), and its linear accuracy is ±2%, ±1%, ±0.3%, ±0.05 % .
D type (logarithmic type): It is often used in the black and white contrast adjustment potentiometer of the TV, and its characteristic is that the coarse adjustment is followed by the fine adjustment.
Z type (exponential type): It is often used in radio volume adjustment potentiometers, which is characterized by fine adjustment first and then coarse adjustment.
All X, D, and Z letters and symbols are generally printed on the potentiometer, and attention should be paid when using it.
