A potentiometer is a 3-terminal variable resistor whose resistance can be manually adjusted to control the flow of electric current. It is also called a pot or pot meter. We can use a potentiometer as an adjustable voltage divider.
In the field of electrical engineering, a device is used to control and alter the electrical resistance and current in any circuit, known as a potentiometer. It offers great precision for measurement purposes in electrical laboratories. It helps us to control electrical resistance with a quite easy process.
In the article, we will thoroughly study potentiometers and their applications, with their working. So, let’s begin with the basic introduction.
Table of contents
What is a Potentiometer?
A potentiometer is a three-terminal electric device used to manually change the electrical resistance in a circuit, behaving as a voltage divider. Sometimes, it is called just as “pot”. The first two terminals of the potentiometer connect on the two ends, and the third terminal connects to the adjustable knob of the potentiometer. The adjustable contact, also known as a “wiper,” performs its motion over a resistor part to change its resistance in a circuit.
The resistor part is made up of two resistors in series. The wiper’s position will decide the voltage divider’s resistance ratio with respect to both series resistors. If you apply reference voltage at the two last corner terminals of the potentiometer, you will get the voltage across the potentiometer. However, the wiper position will determine the magnitude of the voltage across the potentiometer.
Construction of Potentiometer
A potentiometer may look like a tiny piece of equipment, but its construction is made up of different equipment that makes it able to control electricity flow in different devices.
In the middle of a potentiometer, there is a resistive element, and the resistive element opposes the flow of electricity. It is a long and thin strip made up of carbon, cermet, conductive plastic, or a metal film. All these materials offer a path to the flow of current.
Then, the potentiometer has three terminal connections for entering and leaving the electric current. These three terminals connect in such a way that they have opposite faces with resistive elements.
After that, the pot has a slider known as a wiper. This central real part moves over the resistive element to change resistance. This part is usually placed in between the other two corner terminals. All these elements make up the potentiometer by combining.
Potentiometer Symbols
Here are the two symbols of a potentiometer, namely,
(1). IEC Standard
The IEC standard symbol of the potentiometer is shown in the following figure.
(2). ANSI Standard
The ANSI standard symbol of the potentiometer is depicted in the following figure.
How to Measure Voltage Using a Potentiometer?
A potentiometer can be used to measure voltage in an electric circuit. For this, the potentiometer is appropriately tuned to control the electric current passing through the resistor. This allows for a specific voltage drop across each unit length of the potentiometer resistor.
To measure the voltage using a potentiometer, one end of a wire is fixed at the starting point of the resistor, and the other end is connected to the sliding contact or wiper through a galvanometer.
After that, gradually move the sliding contact or wiper along the resistor until the galvanometer shows null or zero deflection. For zero deflection, note the position reading on the resistor on the scale.
Types of Potentiometers
In this section, we will discuss the types of a potentiometer. Here is the list and complete description:
Rotary Potentiometer:
These are the most common types of a potentiometer. They include a circular restive element with a knob or shaft. As the knob rotates, the wiper rotates along the circular resistive element path. Then, we can get a new variable signal of voltage. They are commonly used in radios in volume-changing knobs in electronic devices. Further, they are classified into single-turn, multi-turn, and servo potentiometers. A servo motor can operate the Servo pot to turn the knob automatically.
Slide/Linear Potentiometer:
They include linear resistive elements, and the slider moves along the length of the potentiometer to change the resistance to control and change the incoming voltage. These are employed where linear adjustments are required, such as faders on audio mixers and equalizer control applications. They are categorized into slide pots, dual-side pots, and multi-turn slides. Also, they can be adjusted using a servo motor.
Digital Potentiometer:
In this type, a potentiometer is controlled electronically and has a small value of resistive elements connected in series. They include switches to change the resistance value digitally. They are commonly used in digital audio equipment and instrumentation.
Multi-Turn Potentiometer:
They offer higher precision than a single-turn potentiometer. They offer multiple rotations to complete a full range of resistance. Due to their higher accuracy, this type is used in laboratories requiring more fine adjustments.
Rheostat:
A potentiometer can also be made up to behave as a rheostat. You need to connect the wiper terminal and one ending terminal to avoid infinite resistance if the wiper connection is lost with restive material. It is also called single-variable resistance.
These are types of potentiometers used in multiple applications for their versatile usage.
Advantages
Here is the list of following advantages of a potentiometer:
- They offer adjustable resistance, allowing control voltage in different applications.
- Its efficiency is higher and can be used to measure the potential difference between the two terminals.
- Its process is easy, and anyone can use a potentiometer without any complex process.
- It offers a different range of resistance.
- It consumes less power in its applications.
All the above advantages of it make this small equipment perfect for controlling voltages.
Applications
Here is the list of all applications where a potentiometer is being used. Let’s have a look:
- These are commonly used in electrical equipment, such as volume control in audio equipment.
- They are used in user-controlled devices where input from a user is required.
- They are used in a joystick for machine control.
- They are also used to measure distances or angles as position or angle transducers.
- They are used in medical devices where brightness is needed to increase or decrease for monitoring the patient.
- They are also used for fine-tuning and calibration in user interfaces.
- They can provide position feedback in the robotics arm.
- They are also a part of dimmer switches to increase or decrease the light brightness.
All the above applications of a potentiometer make it suitable for control purposes.
Conclusion
A potentiometer offers great precision for measurement purposes in electrical equipment. They have resistive elements and a wiper to change the resistance by moving on it. This is how it changes the voltage level of a device from the input voltage. It is being used in multiple applications for different controlling purposes with great benefit.
