What is a Potentiometer?
A potentiometer is a three terminal device that acts as a variable resistor. The device allows the user to adjust resistance in a circuit by which the voltage or current is influenced. Potentiometers are used in volume controls, tuning circuits, and also as calibration tools in instrumentation.
The term “potentiometer” was derived from its application to measure the potential difference between two points in a circuit in the early stages of its use.
Construction and Working Principle
A common potentiometer comprises:
Resistive Element: A strip of resistive material, such as carbon, cermet, or wire.
Wiper (Sliding Contact): A movable contact that slides along the resistive element.
Terminals: Three terminals—two connected to the ends of the resistive element and one to the wiper.
Rotary or Linear Mechanism: The mechanism to move the wiper, either rotationally or linearly.
How It Works:
When you vary the wiper, the resistance between the terminals connected to the wiper and the resistive element changes.
This changes the division of voltage across the circuit, effectively acting as a voltage divider.
By using two of the three terminals, a potentiometer can also act as a variable resistor (rheostat).
Types of Potentiometers
Potentiometers come in various forms to suit different applications. Here are the most common types:
1. Rotary Potentiometers:
The most common type, featuring a knob or dial for adjustment.
Often used in audio equipment for volume control.
2. Linear Potentiometers:
The wiper moves in a straight line rather than a circular motion.
Common in industrial and scientific applications requiring precise linear adjustments.
3. Digital Potentiometers:
Controlled electronically using digital signals rather than manually.
Used in automated systems and modern electronic devices.
4. Multi-turn Potentiometers:
Require multiple rotations of the wiper for full resistance adjustment.
Ideal for trimming on high-precision applications.
5. Trimmer Potentiometers (Trimpots):
Small adjustable pots used for calibration purposes during device setup.
Usually operated with a screwdriver.
Potentiometer Applications
Potentiometers are highly versatile and have applications in diverse industries:
1. Consumer Electronics:
Volume Control: In audio systems, potentiometers regulate the sound volume of speakers.
Brightness and Contrast: The adjustments of display settings on monitors.
2. Industrial Systems:
Position Sensors: Measurement of displacement in machinery.
Calibration Tools: Fine-tuning instruments and controls.
3. Automotive:
Utilized in throttle position sensors and other automobile control.
4. Scientific Equipment:
Accuracy fine-tuning in laboratory equipment and testing tools.
5. Robotics
Position feedback in servos and robotic arms.
Benefits of Potentiometers
- Easy to install and use.
- Can be adjusted either manually or electronically.
- Variety is offered in different designs that cater to specific requirements
- Usually very affordable and highly accessible.