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# What is potentiometer?

29.03.2019

Potentiometer is a device capable of separating and regulating voltage with the help of a special wiper (sliding contact).

CONTENTS:

## Potentiometer design

By design, potmeter is similar to a rheostat(a special device for regulating voltage and current in the network, using resistance). However, there is one significant difference between them. This is the number of available terminals. The potentiometer has three of them unlike of two in rheostats.

The device operates as a variable resistor. Two terminals are connected to a resistive element by constant resistance. The third one is connected to the special contact that sliding along surface.

This allows device to perform the function of a resistor, however its operation can be regulated. Such function is carried out by moving the sliding contact with a separate terminal along a special element.

Their position relative to each other will give the current voltage value.

## Potentiometer types

Main purpose of potentiometer is the most often regulating of the voltage value.

Depending on the purpose of the application, a huge number of models are produced.

However, all of them can be divided into main types, depending on the principle of operation - linear and logarithmic.

They differ in the algorithm of voltage change during rotation of sliding contact. In the first case, its ratios will be linear; that means that value will change according to the rotation of the wiper.

In the second type, change of the value is calculated by a special formula, therefore, the ratio of the sliding contact rotation and change of parameters will be different.

According to the criterion of resistance change there are three main groups:

Linear. They indicate the linear ratio of the wiper rotation to the change in resistance. The letter A. denotes this type.

Logarithmic. In these devices, the change between turning the knob and changing the resistance value is calculated by logarithmic function. In such pots, change in the parameter initially has high rates, and then gradually fades away. Such potmeters denoted by the letter B.

Inverse logarithmic (exponential). In such devices, change in resistance to the sliding contact movement over a resistive element is also calculated using a special formula. The difference from the previous type is that the change in resistance parameters occurs in reverse order. That is, first at a slow ratio and then acceleration gradually occurs.

The designations (A, B, C) are international, however, you should always look at the instructions for your device as some manufacturers may use their own labeling.

## Application areas

The simple design of the device ensures its wide application. Today, such equipment is used everywhere and can perform various functions.

Potentiometer can act as: