How do potentiometers work? Ever turned a volume knob on a radio or dimmed a light using a dial? Then you’ve already used a potentiometer—even if you didn’t know it! Potentiometers (or “pots” for short) are simple yet powerful components used to control voltage in electronic circuits.
In this beginner-friendly guide, we break down exactly how potentiometers work, what they’re made of, and where they’re used in real-world devices. By the end, you’ll know how to use them in your own electronic projects.
Table of Contents
- What Is a Potentiometer?
- How Do Potentiometers Work?
- Types of Potentiometers
- Potentiometer Symbol: How to Recognize It in Circuit Diagrams
- How do Potentiometers Work? — Tips for Using Potentiometers
- Summary: How do Potentiometers Work?
What Is a Potentiometer?
A potentiometer is a variable resistor. That means its resistance can be adjusted by turning a knob or sliding a control.
Unlike fixed resistors, which always offer the same resistance, potentiometers give you the flexibility to change how much electrical current flows through a circuit.
There are three main terminals:
- Terminal 1 and Terminal 3: Connect to both ends of a resistive strip.
- Terminal 2 (the wiper): Slides across the strip to pick off a variable voltage.
Depending on how you connect the terminals, you can use a potentiometer as:
- A variable resistor (aka rheostat)
- A voltage divider (for adjusting voltage levels)
The image below shows an example of the use of a potentiometer. In the image, the visible part on the guitar is actually the knob connected to the potentiometer. The actual potentiometer is in the body of the guitar, and the knob attaches to the shaft of the potentiometer. Many electric guitars typically have two potentiometers. That is, one for volume control and one for tone control.
How Do Potentiometers Work?
How do potentiometers work? Let’s keep it simple:
Inside a potentiometer is a resistive strip (made of carbon, cermet, or conductive plastic). The wiper is a movable contact connected to the shaft or slider. When you turn the knob or slide the control, the wiper moves along the resistive strip, changing the resistance. That is, the measured resistance between the wiper and either end or terminal of the resistive strip.
Since a potentiometer varies resistance, it directly influences voltage and current in a circuit—just like any fixed resistor. Once you set the knob or slider, it acts like a resistor of a specific value. This behavior is governed by Ohm’s Law, which relates voltage, current, and resistance.
Two Common Ways to Use a Potentiometer:
1. As a Variable Resistor (Rheostat)
If you connect only two terminals (wiper and one end), the pot acts as a variable resistor, increasing or decreasing resistance in a circuit.
2. As a Voltage Divider
If you use all three terminals, the pot divides the input voltage into a lower output voltage. This is how volume knobs work—they reduce the signal level going to a speaker.
In simple terms:
- More rotation = more resistance = lower voltage output
- Less rotation = less resistance = higher voltage output
Types of Potentiometers
Potentiometers come in a few shapes and forms. Here are the main ones:
(+) ---- Terminal 1
|
|---- Terminal 2 (Output / wiper)
|
(-) ---- Terminal 3
- Connect Terminal 1 to your voltage supply.
- Terminal 3 goes to ground.
- Terminal 2 gives you the variable output voltage.
As you turn the knob, the voltage at Terminal 2 changes smoothly from 0V to the supply voltage.
Potentiometer Symbol: How to Recognize It in Circuit Diagrams
When reading circuit schematics, recognizing the potentiometer symbol is essential for understanding how voltage control or resistance variation is being implemented. While the function of a potentiometer remains the same, the graphical representation can differ slightly depending on whether the schematic follows American (ANSI) or European (IEC) standards.
Let’s explore the most common potentiometer symbols used in electronic diagrams and how to identify them.
USA (ANSI) Potentiometer Symbol
In the United States and other regions that follow ANSI standards, the potentiometer symbol is drawn as a resistor with an arrow pointing to the middle of the resistor. The arrow represents the wiper, which slides across the resistive element to vary the resistance or voltage.
This symbol is straightforward and widely used in hobby electronics, datasheets, and educational materials in North America.
EU (IEC) Potentiometer Symbol
In European schematics, the IEC potentiometer symbol also uses an arrow, but the base resistor is represented as a rectangle rather than a zigzag line. The arrow still indicates the movable wiper, and its angle typically shows that it interacts with the resistive element.
This style is more common in European documentation and conforms to international schematic drawing standards.
By understanding both the USA and EU potentiometer symbols, you’ll be able to interpret circuit diagrams from any source—whether you’re studying datasheets, following online tutorials, or analyzing electronics textbooks. Knowing these symbols also makes it easier to build and troubleshoot your own circuits with confidence.
How do Potentiometers Work? — Tips for Using Potentiometers
- Choose the right resistance value (e.g., 10kΩ is common for analog inputs).
- Use logarithmic pots for audio volume (they match how humans hear sound).
- Use multiturn trimmer pots for precision tuning in circuits.
- Avoid overloading them—check the power rating (usually low, like 0.25W).
Summary: How do Potentiometers Work?
To recap:
- A potentiometer is a variable resistor that adjusts resistance or voltage.
- It works by sliding a contact (wiper) along a resistive strip.
- It can be used as a rheostat (variable resistor) or a voltage divider.
- Common in audio, lighting, control systems, and DIY electronics.
So the next time you twist a knob or slide a control, you’ll know exactly what’s happening behind the scenes—thanks to the humble potentiometer!