What is Potentiometer – Diagram , Working , Advantages

What is Potentiometer

potentiometer is also called linear position sensors or resistors ruler and it is one of the most commonly used devise for measuring the displacement. Potentiometer is a primary sensor which converts the linear motion or the angular motion of a shaft into change in resistance. It is a type of resistive displacement sensor. Linear potentiometers are sensors that produce a resistance output proportional to the linear displacement or position. Linear potentiometers are essentially variable resistors whose resistance is varied by the movement of a slider over a resistance element.

Rotary potentiometers are sensors that produce a resistance output proportional to the angular displacement or position. They can be either wire-wound or conductive or cylindrical

Figure 1.23 illustrates the basic principle of a linear potentiometer. The linear potentiometer employs an electrically conductive linear slide member (also called wiper) connected to a variable wire wound resistor (winding) that changes resistance to be equated to the linear position of the device which is monitored. As the sliding contact moves along the winding, the resistance is changed in linear relationship with the distance from one end of the potentiometer. To measure the displacement, a potentiometer is typically wired as a “voltage divider” so that the output voltage is proportional to the distance traveled by the wiper. A known voltage is applied to resistor ends. The contact is attached to the moving object of interest. The output voltage at the contact is proportional to the displacement. The resolution is defined by the number of turns per unit distance and it is affected by the loading effects of the voltage divider circuit.

One of the most common uses of modem low-power potentiometers is as an audio control device. Both sliding pots (also known as faders) and rotary potentiometers (commonly called knobs’) are regularly used to adjust loudness, frequency attenuation and other characteristics of audio signals.

potentiometer - Linear and Rotary
potentiometer – Linear and Rotary

The following Factors are to be considered while selecting the potentiometers.

(i) Operating temperature
(ii) Shock and vibration
(iii) Humidity
(iv) Contamination and seals
(v) Life cycle
(vi) Dither

Applications of Potentiometer

(i) Linear displacement measurement
(ii) Rotary displacement measurement
(iii) Volume control
(iv) Brightness control
(v) Liquid level measurements using floats

Advantages of Potentiometer

(i) It is easy to use
(ii) The cost is low
(iii) It has high-amplitude output signal
(iv) It is a proven technology
(v) It has rugged construction
(vi) Electrical efficiency is very high
(vii) It is available in different forms, ranges and sizes

Disadvantages of Potentiometer

(i) It has limited band width
(ii) Frictional loading is more
(iii) It has limited operating cycle

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