It is essential for electronics enthusiasts to thoroughly understand potentiometers. These variable resistors are basically leveraged in various applications such as volume controls and sensor calibration. Extensive insights about potentiometers, including their features and types facilitate precise control and adjustment of electronic devices. All for optimal performance.
Let’s discuss this in detail.
What is a Potentiometer?
A potentiometer is a three-terminal variable resistor that enables the adjustment of voltage levels in a circuit. It consists of a resistive element with a sliding contact (wiper) that can be moved along its surface.
The resistance between the wiper and either end of the resistive element can be varied if the position of the wiper is changed. In this way, it allows for precise control over the output voltage.
Now if you are someone who doesn’t know much about the potentiometer switch then let us explain the concept of a potentiometer with an example.
If you’re tuning in to your favorite radio station You reach over and twist the volume knob, right? Its knob will definitely work like a useful gadget that helps manage how much electricity flows through it.
As you also know there will be a long, thin strip inside the knob with a little dot that can slide along it. When you turn the knob, you’re actually moving this dot. As you move it, the potentiometer changes how much electricity can pass through it.
This ability to control the flow of electricity is actually where the potentiometer pinout works. It helps to adjust the brightness of a light or the speed of a motor by simply turning a knob.
Potentiometer Pinout
A potentiometer pinout typically consists of three pins or simply you can also call them its terminals. All of them are used to connect it in a circuit. The pinout refers to the arrangement of the three terminals, which are the main points where you can connect wires or other components.
Here is a detailed explanation of the three terminals of the potentiometer switch on which its whole working lies.
1- Terminal 1 (CCW)
This is the first terminal of the potentiometer. It is often referred to as the “CCW” (Counter Clockwise) terminal. When you look at the potentiometer from the front with the shaft pointing towards you, this terminal is on the left side. This terminal is connected to one end of the resistive element inside the potentiometer.
2- Terminal 2 (Wiper)
The middle terminal is called the “Wiper” terminal. When you adjust the potentiometer, it is connected to the moving contact or wiper that slides along the resistive element. This terminal allows you to tap into the variable voltage divider that the potentiometer creates.
3- Terminal 3 (CW)
This is the third terminal of the potentiometer which is often labeled as “CW” (Clockwise). When looking at the potentiometer from the front with the shaft pointing towards you then this terminal is on the right side. This terminal is connected to the other end of the resistive element.
Potentiometer Circuit Diagram
Types of Potentiometer
There are basically two types of potentiometers. Both of them are classified according to their shapes. Let’s study both of them in detail to help you understand their characteristics.
Rotary Potentiometer
Rotary potentiometers are designed to allow for the adjustment of voltage or current in electronic circuits. They are commonly used in devices like volume controls on radios and amplifiers.
In a rotary potentiometer, there are two terminal contacts with uniform resistance in a semi-circular pattern. A middle terminal is connected to the resistance through a sliding contact attached to a rotary knob. When you turn the knob it moves the sliding contact along the resistance.
This way it allows for control of the voltage between one end of the resistance and the sliding contact. These are also known as “POTs” and are used in things like adjusting the charging voltage of a battery in substations.
Examples
Linear Potentiometer
Linear potentiometers are similar to rotary potentiometers but are designed for linear motion instead of rotation. They are used in applications where linear movement is required to adjust resistance.
These are similar to rotary ones, but the sliding contact moves along a straight resistor instead of in a circle. They are used to measure voltage in a circuit branch and measure the internal resistance of a battery cell. Consequently, you will see more probably a linear potentiometer most commonly in music and sound mixing systems for equalizing sound.
Characteristics of Potentiometer
If you are an engineer or a designer and going to purchase a potentiometer then you must see the following characteristics of a potentiometer. All of these characteristics allow you to select the right potentiometer for a specific application.
Let’s have a look at all of the important characteristics of a potentiometer.
Taper
The taper describes how its resistance changes concerning the physical position of the knob. Linear taper means the resistance changes evenly as you turn the knob on. It will make it suitable for applications where a linear change in resistance is needed, like in volume controls.
Logarithmic (or audio) taper means the resistance changes more at one end of the knob’s range than the other. It is useful for applications where the human ear perceives loudness on a logarithmic scale, like in audio equipment. We will recommend you consider the taper as it is crucial to achieve the desired response in the circuit.
Marking Codes
Potentiometers are marked with codes that indicate their maximum resistance. For example, If a pot is labeled as 100K then it means it has a maximum resistance of 100,000 ohms.
This information is vital when selecting a potentiometer to ensure it meets the requirements of the circuit.
Resistance of Potentiometer
This characteristic refers to the sudden change in resistance that occurs when the wiper moves across the metal contacts at the ends of the potentiometer. This can cause a discontinuity in the resistance value, which may be undesirable in some applications.
It is crucial to consider this characteristic when designing circuits that require smooth and continuous changes in resistance.
Resolution of Potentiometer
The resolution of a potentiometer is known as the smallest change in resistance it can achieve. For example, If you see a pot with a resolution of 0.5 ohms then it means that the resistance can be changed in increments of 0.5 ohms.
This is important in applications where precise adjustments are necessary, such as in calibration circuits.
Durability and Longevity
Potentiometers can wear out over time, especially if they’re used a lot. So it is important for you to know how long a potentiometer is expected to last and how durable it is. Because it will help to make sure the circuit keeps working reliably for as long as you need it to.
Temperature Coefficient
The temperature coefficient of a potentiometer tells you how much its resistance changes when the temperature changes. This is crucial in places where the temperature can go up and down a lot, as it can affect how well the circuit works and how accurate it is.
Mechanical Size and Mounting
Potentiometers, or pots, come in different shapes and sizes. It’s important to pick one that fits well in the device you’re using it for. This will also help you install it correctly and will work in the best way as it’s supposed to.
Wrapping Up
Potentiometers play crucial roles in various everyday devices. They come in different types and all of them are used according to their applications. You must be familiar with all and each of their working principles. Only then you will be able choose the right type for your circuit board.
If you have any questions about potentiometers, don’t hesitate to reach out. Our PCB engineering team is here to help with any inquiries you might have.
Frequently Asked Questions
How to wire a Potentiometer?
Wiring a potentiometer is a very simple process. To do it, just connect one end of the potentiometer to a power source and the other end to the ground. The middle terminal, called the wiper, should be connected to your circuit.
What is a “String Potentiometer”?
A string potentiometer is just like a measuring tape for how far something has moved in a straight line. It has a string that is connected to the object you want to measure. As the object moves, the string pulls on a spring-loaded wheel that turns a potentiometer, which measures the distance the string has been pulled.
Where are the applications of Joystick Potentiometers?
Joystick potentiometers are often found in gaming controllers, remote-controlled vehicles, and industrial control systems. They work by changing their resistance as you move the joystick.
“Rheostat vs Potentiometer” What is the main difference between both?
The key difference between a rheostat and a potentiometer is how they’re used. A rheostat is like a faucet for electric current that controls how much flows through a circuit. On the other hand, a potentiometer divides voltage in a circuit which also creates a variable output voltage.
