A rotary potentiometer is a common electronic component used to adjust the resistance value by manual rotation. It is widely applied in scenarios such as volume control, brightness adjustment, and voltage division. The following is its detailed description:

1. Basic structure

Resistor body: Usually made of carbon film, metal film or conductive plastic, it is arc-shaped or circular in shape and is the core part of the potentiometer.

Sliding contact (brush) : Connected to the rotating shaft, it slides on the resistance body as it rotates, changing the contact position.

Rotating shaft: A knob or handle operated by the user, mechanically connected to a brush.

Terminal pins

Two pins: Connect the two ends of the resistor body and fix the resistance value (total resistance value).

Middle pin: Connect the brush and output the variable resistor.

2. Working Principle

The rotating shaft drives the brush to move on the resistor body, changing the resistance value between the middle pin and the two end pins, thus achieving the function of voltage division or resistance variation.

Voltage division mode: Connect power supplies (VCC and GND) at both ends, and output a variable voltage at the middle pin.

Variable resistance mode: Use the middle pin and either end pin as the variable resistor.

3. Main types

Single-turn potentiometer: The rotation Angle is usually 270° to 300°, suitable for general adjustment.

Multi-turn potentiometer: It can be rotated multiple times (such as 10 turns) to achieve high-precision adjustment.

Switch potentiometer: Integrated switch function. Rotating to the end point can turn the circuit on or off (such as the power supply of an old-fashioned radio).

Linear/logarithmic type

Linear (Type B) : The resistance value has a linear relationship with the rotation Angle (such as volume control).

Logarithmic (Type A) : The resistance value changes in a logarithmic curve (suitable for audio adjustment).

4. Key parameters

Resistance range: Common ones include 1kΩ, 10kΩ, 100kΩ, etc., marked as the total resistance value (e.g., "10k").

Tolerance: Resistance value accuracy, usually ±10% to ±20%.

Rated power: Generally 0.1W to 2W. Overload may cause damage.

Rotational life: Approximately 50,000 times for carbon film type, and up to 1 million times for conductive plastic.

Protection grade: Some models are equipped with dust-proof and moisture-proof designs (such as IP54).

5. Application scenarios

Audio equipment: Volume and pitch adjustment.

Industrial control: Instrument calibration, motor speed regulation.

Consumer electronics: Adjustment of display brightness and contrast.

DIY Project: Analog input adjustment for Arduino and Raspberry PI.

6. Precautions for Selection

Resistance matching: Select based on circuit requirements (for example, 10kΩ is commonly used in voltage divider circuits).

Type selection: Linear/logarithmic type should match the application scenario.

Dimensions and installation: The panel opening dimensions and shaft lengths (such as 6mm/6.35mm) must be compatible.

Feel requirements: Some models come with scales or damping sensations, suitable for precise adjustment.

7. Common Faults and Maintenance

Poor contact: Noise caused by worn or oxidized brushes can be treated with an electronic cleaner.

Resistance drift: Carbon film aging, needs to be replaced.

Mechanical damage: Excessive rotation may cause the shaft to break. Avoid violent operation.

8. Sample model

Common type: B10K (linear 10kΩ), A50K (logarithmic 50kΩ).

Precision type: Multi-turn 3296W (such as 1kΩ adjustable resistor).

High-temperature resistant type: Military or industrial grade metal film potentiometers.