Potentiometers

Informally known as 'pots', potentiometers are three-terminal resistors with a sliding or rotating contact which forms adjustable voltage dividers. If only two terminals are used, they act as variable resistors or rheostats. They consist of a resistive element, a sliding contact (wiper) that moves along the element and electrical terminals at each end. There is a mechanism that moves the wiper. There are a variety of potentiometers with different mechanisms which can slide or rotate. A linear slider potentiometer visually indicates the setting but a rotary potentiometer consists of a knob. They are also classified according to the material of the resistive element. Some of them are user-accessible whilst others are enclosed within equipment intended to be adjusted to calibrate the components during manufacture such as a digital potentiometer. Potentiometers are used to control electrical devices such as the volume controls on audio equipment and rotary types are built into position transducers such as joysticks for electronic games. Another domestic use is to control switching in light dimmers. Touch screen technology uses a two-dimensional membrane potentiometer. In DC motors, they are the simplest way of measuring angle or speed and are essential components in position sensors. Similarly, they control input for electronic circuits.