Classification of resistors and potentiometers and their salient characteristics
1. Concept and application of resistors
Resistors are indispensable components in circuit design and play a key role in controlling current and voltage. The basic function of a resistor is its ability to block electrical current, which is affected by a variety of factors, including the conductor's size, material, and temperature. In electronic products, what we usually call "resistance" refers to the specific component of a resistor. The unit of resistance is ohms (Ω), represented by the Greek letter "Ω", while larger resistance units include kiloohms (kΩ) and megaohms (MΩ). In electronic equipment, the quality of resistors directly affects the stability of the circuit, and its importance is evident.
2. Classification of resistors
Resistors are classified mainly based on their structure and can be roughly divided into two categories: fixed and variable.
(1) Diversity of fixed resistors
Fixed resistors can be subdivided into four types: wirewound resistors, solid core resistors, thin film resistors and sensitive resistors according to their different production materials and processes. Wirewound resistors come in many types, including general purpose, precision, high power and high frequency. Thin film resistors include carbon film resistors, synthetic carbon film resistors, metal film resistors, metal oxide film resistors, etc. Solid resistors are divided into inorganic and organic types, while sensitive resistors include pressure-sensitive, heat-sensitive, light-sensitive, force-sensitive, gas-sensitive and moisture-sensitive types, which are used to sense and respond to specific environmental changes.
(2) Application of variable resistors
Variable resistors are mainly divided into slide wire rheostat and potentiometer. The potentiometer is the most widely used variable resistor. It has three joints and its resistance can be continuously adjusted within a certain range. Potentiometers are divided into film and wirewound according to the resistor material, each with different models and characteristics.

Detailed classification of potentiometers
Potentiometers can be divided into two types: rotary type and direct sliding type according to the movement mode of the adjustment mechanism. According to different structures, potentiometers can be divided into single-link, multi-link, with switch and without switch types. The switch forms include rotary type, push-pull type and button type. Potentiometers have various uses, including ordinary potentiometers, precision potentiometers, power potentiometers, trimmer potentiometers and special potentiometers. Potentiometers can also be divided into linear and nonlinear types based on the relationship between resistance and rotation angle.
Characteristics and applications of potentiometers
X-type (linear) potentiometers are often used for focus adjustment of oscilloscopes and zero-adjustment operations of multimeters. Their linear accuracy is high, reaching ±0.05% to ±2%. D-type (logarithmic) potentiometers are commonly used in the black and white contrast adjustment of TV sets, and are characterized by coarse adjustment first and then fine adjustment. Z-type (exponential) potentiometers are mostly used to adjust the volume of radios. Its characteristic is to adjust finely first and then coarsely. When selecting and using potentiometers, understanding these different types of potentiometers and their application scenarios is crucial to ensuring the accuracy and effectiveness of your circuit design.