A Potentiometer is a commonly used electronic component that controls the voltage, current or signal strength in a circuit by manually adjusting and changing the resistance value. The following is its detailed description:

1. Basic structure

Resistor body: Usually made of carbon film, metal film, conductive plastic or winding material, it provides a continuous resistance path.

Sliding contact (brush) : Connected to a rotatable or sliding shaft, it comes into contact with the resistor body and changes the effective resistance value.

Pin/terminal

Both ends: Fixed ends (connect the two ends of the resistor body).

The third terminal: Sliding terminal (output variable voltage or voltage divider signal).

2. Main types

Rotary potentiometer: Adjusted by a knob (such as volume control).

Linear sliding potentiometer: Adjusted by linear sliding (such as a dimmer).

Multi-turn potentiometer: It needs to be rotated multiple times to complete full-range adjustment, with higher precision.

Digital potentiometer: Controlled by digital signals (such as I²C interface), without mechanical contacts.

Switch potentiometer: Integrated switch function (like the volume switch of an old-fashioned radio).

3. Key parameters

Resistance range: Common ones include 1kΩ, 10kΩ, 100kΩ, etc. They are marked as nominal resistance values (for example, "B10K" indicates linear 10kΩ).

Resistance value variation characteristics

Linear (Type B) : The resistance value has a linear relationship with the rotation Angle (formula: R = kθ).

Logarithmic (Type A) : Suitable for volume control (human ear logarithmic response).

Index (Type C) : Contrary to Type A, it is less common.

Rated power: Usually 0.1W to 2W. Exceeding this range may cause overheating and damage.

Resolution: The resolution of wound potentiometers is relatively low, while that of conductive plastics is relatively high.

Mechanical life: Carbon film is approximately 10,000 times, while conductive plastic can reach 500,000 times.

4. Working Principle

Voltage division mode: As a three-terminal device, the input voltage is applied across both ends, and the sliding terminal outputs voltage division (formula: Vout = Vin × (R2 / (R1 + R2))).

Variable resistance mode: Only the sliding end and one end are used as variable resistors.

5. Application scenarios

Analog signal regulation: Audio equipment (volume, pitch), dimming circuits.

Calibration circuit: Adjust the sensor sensitivity or amplifier gain.

User input control: game controller, instrument panel knob.

6. Precautions for Selection

Environmental factors: The sealed model is dust-proof and moisture-proof, and industrial-grade high-temperature resistant.

Installation methods: PCB installation, panel installation or with casing.

Precision requirements: Multi-turn potentiometers are suitable for fine-tuning, while ordinary knobs are used for rough adjustment.

7. Frequently Asked Questions

Noise: Poor contact caused by aging of the carbon film or oxidation of the contacts is manifested as noise or signal jumping.

Mechanical wear: Frequent adjustments may reduce the lifespan. It is necessary to choose a model with high durability.

Load effect: Connecting a low-impedance load to the output terminal will cause the voltage division to be nonlinear.

8. Symbols and Annotations

Circuit symbol: A resistor with an arrow indicates an adjustable terminal.

Model marking: For example, "RK09" indicates a certain series of rotary potentiometers.