Potentiometer Principle

Introduction

A potentiometer is a three-terminal resistor. One of the three terminals is variable, while the other two are fixed. It is an electric component used to evaluate unidentified voltages by comparing them to known voltages, which can be drawn from a cell or any other supply source. In other words, it is a device used to measure the EMF (electromotive force) and internal resistance of a specific cell. A potentiometer could also be used to differ the resistance in order to measure potential differences. Even though potentiometers are most commonly used to control volume in radios and other audio-related electronic devices, they are also useful in the manufacture of electronic parts because they provide a means of adjusting circuits to obtain the appropriate outputs.

Body

Potentiometer Construction:

 The potentiometer’s structure is divided into two parts – the sliding part and non-sliding part. The sliding contact is known as a wiper. The sliding contacts move in either a translational or rotational direction. Some potentiometers implement both translational and rotational motions. Because this type of potentiometer uses a resistor in the shape of a helix, it is known as a heliport.

The potentiometer has three terminals. Two are linked to the resistor, and the third is attached to the movable wiper via wire. The variable potential is tapped off as a result of this moving wire. The variable resistor is controlled by the third terminal. The third terminal’s potential is controlled by varying the applying potential at the resistor’s end. 

A position sensor is a linear potentiometer. It evaluates displacement along a single axis, be it up and down or left and right.

Linear potentiometer:

Linear potentiometers are frequently rod-actuated and are linked to an inner slider or wiper carrier. The rod will be linked to a gadget that needs to be measured. The linear potentiometer divides an applied regulated voltage proportionally over its operating capacity and offers a proportional voltage output depending on the role of the wiper. Linear potentiometers are contacting sensors, which implies that the moving parts initiate contact with each other during operation. This makes them durable enough to be used in a wide range of applications while remaining reasonably priced. They can operate in a wide temperature range and have a longer lifespan, good accuracy, and reproducibility.

Digital potentiometer: 

Digital potentiometer can be built in two ways; the first method to make a digital potentiometer is from a resistor ladder integrated circuit and the second method is by using a digital-to-analog converter. The resistor ladder integrated circuit method is quite popular.  Every stage on the resistor ladder has its own toggle that connects it to the potentiometer’s output port. The resistance ratio of the digital potentiometer is determined by the picked stage on the ladder. The series of steps is normally represented by a bit value, for example, 8 bits means total 256 steps; 8 bits is by far the most popular, but resolutions ranging from 5 to 10 bits (32 to 1024 steps) are also available. 

Digital potentiometers have separate resistance steps rather than the apparently continuous control of a multi-turn resistive potentiometer. Another limitation is that special logic is frequently supposed to check for zero crossing of an analog AC signal in order to change the resistance value without causing an audible click in the output of audio amplifiers. 

Bourns potentiometer:

Bourns created a miniature potentiometer for applications that required only rare adjustments.  Bourns potentiometer is advanced plastic moulding and precision manufacturing methods to create a potentiometer that was small, accurate, and cheap.

Conclusion

1. The potentiometer is very precise because it determines unknown voltages using the comparing approach instead of the deflection pointer method.
2. It attempts to measure the null or balance point, which does not necessitate the use of power.

3. Because no current is flowing through the potentiometer when it is balanced, its operation is free of source resistance.