Rheostat vs Potentiometer: Uses, Differences & Examples

Author: David Marriott, Spectra Symbol CEO

From dimming LEDs to powering small motors, discover why potentiometers often do the work of rheostats while saving money and adding versatility.

If you’re tinkering with electronics, you’ll eventually run into a project where you need to control how electricity behaves — maybe you want to dim an LED, adjust the volume of a speaker, or regulate the speed of a motor. Two components often appear in these scenarios: the rheostat and the potentiometer.

At first glance, they look similar, and they’re both types of variable resistors. But they aren’t used in exactly the same way. Knowing the difference can help you choose the right part for your next build — and in many cases, it opens the door to using a potentiometer as a more flexible substitute.

In this post, we’ll break down what rheostats and potentiometers are, how they differ, and where each is most useful. We’ll also show you why potentiometers (like those designed by Spectra Symbol) are a great option when you want flexibility, reliability, and cost-effectiveness.

What is a Rheostat?

A rheostat is a variable resistor designed to control the current flowing through a circuit. It does this by adjusting the resistance in series with a load.

Terminals: 2 (one fixed, one connected to a sliding contact or wiper)
Function: Controls the amount of current passing through a device
Common Uses: Light dimmers, fan speed controllers, heaters, and other applications where adjusting current directly is useful

Think of a rheostat as a current throttle. When you increase resistance, you restrict the flow of electricity, which reduces current and lowers output (like dimming a lamp). When you decrease resistance, more current flows.

In the early days of electronics, rheostats were everywhere. Today, they’ve largely been replaced by more efficient electronic methods of controlling current (like transistors and pulse-width modulation). But they’re still useful for certain applications — especially simple circuits or high-power loads where a direct, mechanical current control is effective.

What is a Potentiometer?

A potentiometer is also a variable resistor, but with a slightly different design and a wider range of uses.

Terminals: 3 (two connected to the ends of a resistive track, and one to the sliding contact or wiper)
Function: Can act as a voltage divider when all three terminals are used, or as a rheostat when only two are connected
Common Uses: Audio volume knobs, sensor inputs, adjustable power supplies, and position measurement devices

In everyday life, you’ve probably used potentiometers more often than you realize. The volume knob on a radio or guitar, the joystick in a game controller, and even a classic round thermostat on the wall are all potentiometers at work.

For hobbyists, potentiometers are particularly handy because of their flexibility. Want to adjust the brightness of an LED? You can wire a potentiometer like a rheostat. Want to measure a variable input on an Arduino? Use all three terminals, and it acts as a voltage divider.

Rheostat vs Potentiometer: Key Differences

Here’s a side-by-side comparison that makes the contrast clear:

The takeaway: rheostats are more specialized, while potentiometers give you options.

Can a Potentiometer Replace a Rheostat?

The short answer: sometimes, yes.

Small-scale hobby projects: If you’re building a circuit to dim an LED, control a low-power motor, or tweak the output of a small device, a potentiometer can stand in as a rheostat. Just wire two of its three terminals, and it functions like a current-control device.
Voltage divider setups: When you want to provide a varying signal to a microcontroller (like an Arduino or Raspberry Pi), a potentiometer offers functionality a rheostat simply can’t.

However, there are some caveats:

High-power loads: Rheostats are generally better suited for handling large amounts of current in industrial applications. Potentiometers are not designed to dissipate the same level of heat or energy.
Durability under stress: Rheostats tend to be more robust in heavy-duty scenarios, whereas potentiometers are optimized for control, precision, and flexibility.

For most hobbyist-level builds, though, a potentiometer is often the smarter choice. It’s affordable, adaptable, and widely available.

Why Spectra Symbol Potentiometers?

Here’s where Spectra Symbol comes in. While many potentiometers are designed only for basic circuit control, Spectra Symbol has spent decades advancing potentiometer technology for both industrial and hobbyist applications.

Ultra-thin and lightweight: Perfect for projects where space is limited.
Flexible design: Our potentiometers can integrate seamlessly into applications where traditional, bulky rheostats wouldn’t fit.
Cost-effective: Ideal for hobbyists and designers who want performance without breaking the budget.
Trusted in sensor technology: From medical equipment to consumer electronics, Spectra Symbol potentiometers are used in applications that demand reliability.

This expertise positions Spectra Symbol not just as a parts supplier, but as an authority in sensor technology. By choosing a Spectra potentiometer, hobbyists can experiment with confidence, knowing they’re working with components trusted across industries.

10 Real-World Hobbyist Examples

Here are ten practical projects where a potentiometer can step in as a direct substitute for a rheostat— offering flexibility and lower cost while still getting the job done:

Conclusion

When it comes to rheostat vs potentiometer, the key is understanding their roles:

A rheostat is a two-terminal current controller.
A potentiometer is a three-terminal voltage divider that can double as a rheostat when needed.

For hobbyists, the flexibility of a potentiometer often makes it the more practical choice. And when you want quality components designed by experts in sensor technology, Spectra Symbol’s potentiometers provide reliability and versatility at a cost that makes sense for experimentation and design.

So the next time you’re building or fine-tuning a project, remember: with the right potentiometer, you might not need that rheostat after all.

Explore Spectra Symbol’s potentiometer line and see how they can simplify your next project.