Potentiometer vs. Rheostat: 7 Key Differences, Definition & Using

Potentiometer vs. rheostat: You probably remember this from when you were a young, inexperienced college student who kept tinkering with potentiometers during your first electronics classes.

You must have suddenly realized that all of these parts could be used in everyday devices, but you might not have known it.

Variable resistors like potentiometers and rheostats make it much easier to change the amount of voltage drop in each leg of a system.

Even though these parts have similar basic functions, they are very different and may not be the best replacements for one another. So, what makes these parts different, and why are they better for different applications?

When should you use a potentiometer instead of a rheostat, and what should we look for in the datasheet specifications to choose the right part?

What Is Potentiometer?

A potentiometer is a resistor with three terminals, a divider that can be changed, and a sliding contact that can be used to change the voltage.

What Is Rheostat?

A rheostat is a type of variable resistor that connects a wiper to one side through two terminals.

Potentiometer And Rheostat Similarities

Potentiometers and rheostats have comparable constructions and perform in very similar ways, such as controlling voltage and current distribution in a circuit.

This looks like a simple design, but the way all of these parts are put together makes them useful for many different things.

Potentiometer vs. Rheostat

The Main Difference Between Rheostat And Potentiometer

The most important difference between a potentiometer and a rheostat is the number of terminals. A potentiometer has three connections: two outputs and one input.

A rheostat, on the other hand, only has two (an input and an output). Because it has three ends, a potentiometer can be used as a rheostat if one end is left floating. But the opposite isn’t quite right either.

A rheostat can never be used as a potentiometer without an extra resistor and an earthing connection to the output of the rheostat.

You can think of a potentiometer as a variable voltage divider. When you turn the knob on the device, a sliding contact makes a voltage divider between the two outputs and the one input.

Because of this, dividing voltage is the most basic way to use a potentiometer. Using a rheostat, which is just a potentiometer with too much resistance at the second output, it controls how much power the output-linked load gets as a whole.

If the resistance of the load and the rheostat are the same, most of the power goes to the load.

Differences Between Potentiometer and Rheostat

Before we talk about how potentiometers and rheostats are different, you should know what these two words mean. A potentiometer is a common name for a resistor section with three ends. Both the potentiometer and the rheostat can be used in two different ways that can be changed.

This section will show you how a potentiometer is different from a rheostat in the most important ways. But if you want to know more about how a potentiometer is different from a rheostat, click here.

Description

A potentiometer is a type of resistor that has three contacts that can be moved and a voltage divider that can be changed. On the other hand, a rheostat is a special type of variable resistor with two terminals that connect one side to the wiper.

Use

A potentiometer is a device or part used in electronics to measure something. With a rheostat, you can change how much resistance a circuit has.

Makeup

A potentiometer is made of resistant materials like graphite and resistance wire. On the other hand, a rheostat is made of different things, like metal films and carbon ribbons.

Function

In most diagrams, the voltage is changed with the help of a potentiometer. A rheostat is a tool that is often used to control the amount of current in a system.

Main Function

The main job of a potentiometer is to divide voltage. The main job of a rheostat is to control the flow of electricity.

Voltage vs. Current

The potentiometer arrangement is used to give voltage to any system. In a series system, the rheostat is used to control the amount of current.

Application

A potentiometer is a low-power device that can be used to control sound and TV or as a transducer. Fans and mixers, which have a lot of power, use rheostats to control how much power they use.

2 Terminal vs. 3 Terminals

All three terminal systems can be used as a potentiometer when POT is in use. In the rheostat model, one edge terminal and one centre terminal are used.

Connection

To control the flow of electricity, a potentiometer should be connected in parallel to the system, while a rheostat should be connected in series to other parts of the circuit.

Voltage Dividing

The rheostat can’t separate and control voltage, but the potentiometer can be used as a voltage divider.

Flexibility

Potentiometers can be used as rheostats. But you can’t use one instead of the other.

Potentiometer vs. Rheostat: Practical Applications

A potentiometer changes the voltage at certain terminals. It is used in the power industry to test how well DC motors are working.

It can also be used to change how audio equipment sounds. Both types of older radios require you to do the same thing over and over to change the frequency.

Selecting a Mechanical Potentiometer vs. Rheostat

Even though a potentiometer can be programmed to do the same things as a rheostat, it’s important to remember that the two parts are slightly different. Here are some of the most important rules:

Maximum Resistance

Take note of the device’s maximum resistance, which will tell you how much voltage and current the load can take.

Typically, resistance ranges between tens of ohms and kOhms.This should work well with your power source and the amount of current you need.

Potentiometer vs. Rheostat

Wiper Resistance

A rheostat’s wiper resistance is very important and should be very low for the right amount of current to flow to the load.

When using a potentiometer to send voltage to a high-impedance load, the resistance of the wiper is not important because it is always much lower than the resistance of the load.

In any case, because the wiper resistance is connected to the load resistance, you need to think carefully about how much wiper resistance you can handle.

Taper style

When the wider is moved, the taper changes to show how the device’s resistance, or how the resistance is distributed across the slide, changes.

Linear taper is best when the voltage or current going to the load needs to be changed in a straight line.

One example is an operational amplifier with a part in the feedback loop. Logarithmic and an audio taper designed for audio systems are two other types of taper.

Power rating

Like other resistors, potentiometers and rheostats have a power rating. The component can be hurt by too much power.

Tolerance and hysteresis

Potentiometers and rheostats are electromechanical parts. The winding structure and hysteresis can sometimes cause the resistance tolerance to vary by 10–20%.

Precision parts will have tighter tolerances and be able to be used over and over again (lower hysteresis).

Conclusion

So, a rheostat and a potentiometer both measure different things, like voltage and current, but they both use the movement of a slider to make a big change in the thing they need to measure.

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