A Rotary Switch Potentiometer is an electronic component that combines the functions of a rotary switch and a potentiometer. It is widely used in scenarios such as signal regulation, volume control, and power switching in circuits. The following is its detailed description:
1. Basic structure
Rotating shaft: Users can adjust the resistance value or switch the position of the switch through the rotating shaft.
Resistor body: Usually made of carbon film, metal film or conductive plastic, it determines the resistance range and linear characteristics.
Sliding contact (brush) : It moves along with the rotating shaft to change the effective resistance value of the resistor body.
Switch mechanism: Integrated inside the potentiometer, it turns the circuit on or off by rotating or pressing.
Shell: Protects the internal structure and provides installation and fixation (such as threaded or snap-on design).
2. Main types
Single-channel/multi-channel potentiometer
Single connection: Independently adjust one signal.
Multi-link (such as dual-link) : Synchronously control multiple signals (such as stereo volume).
Linear (Type B) and logarithmic (Type A) :
Linearity: The resistance value change is directly proportional to the rotation Angle (suitable for voltage divider circuits).
Logarithm: The resistance value changes along a logarithmic curve (suitable for volume control and in line with human auditory characteristics).
Potentiometer with switch
Rotary switch: Rotate to a specific position to trigger the switch (such as the power switch of an old-fashioned radio).
Push-pull switch: The switch function is achieved by pulling out or pressing the shaft (such as a volume knob with a switch).
3. Key parameters
Resistance range: Common ones include 10Ω to 1MΩ. The selection should be based on the circuit requirements.
Rated power: Usually 0.1W to 2W. Exceeding this range may cause overheating and damage.
Rotational life: Carbon film potentiometers can last approximately 10,000 times, while conductive plastics can exceed 100,000 times.
Rated current of the switch: usually 0.5A to 5A (AC/DC), used to control the on and off of the circuit.
Linear accuracy: ±10% to ±20%. Special models should be selected for high-precision applications.
4. Typical applications
Audio equipment: Volume/tone adjustment (such as power amplifiers, guitar effectors).
Power control: A power knob with a switch (such as a desktop radio).
Industrial equipment: Calibration of instrument and meter parameters, motor speed control.
Lighting adjustment: Brightness control in the dimming circuit.
5. Precautions for Selection
Environmental adaptability
Dust and water resistant models (such as IP67) are suitable for outdoor or industrial environments.
High-temperature resistant materials (such as ceramic substrates) are used in high-power consumption scenarios.
Installation method
Panel installation (nut fixation), PCB installation (through-hole or surface mount).
The shaft length and shaft diameter need to match the equipment structure (such as 6mm diameter and 15mm shaft length).
Special Requirements
When encoder function is required, select a digital potentiometer.
If a memory function is required, a non-volatile storage type can be selected.
6. Common Issues and Maintenance
Poor contact: Caused by dust or wear, it can be sprayed with an electronic cleaner.
Mechanical wear: Frequent rotation can easily cause damage to the carbon film, so a long-life model should be selected.
Switch failure: Check for oxidation of the contacts or fatigue of the spring, and replace them if necessary.
7. Representative model examples
ALPS RK097: Audio potentiometer with push-pull switch, resistance value 10kΩ to 100kΩ.
Bourns 91 series: Industrial-grade multi-turn precision potentiometers, with a rotational life of up to 500,000 times.
Omeg B1K: Low-cost carbon film potentiometer, suitable for general circuit regulation.
