A potentiometer is used to manually increase or decrease the amount of current flowing through a circuit. It does this by altering the amount of resistance to the current. A typical application would be a volume knob on a radio, or a joystick.
The potentiometer is essentially a resistor with three terminals. A slide or wiper is used to make an adjustable voltage divider. The potentiometer has two strips of material – a conductive strip which conducts current into the circuit when the control is used in one direction, and a resistive strip which turns down the current when the control is used in the other direction.
As ‘potentiometer’ is a bit of a mouthful, these useful but simple tools are usually called ‘pots’. They are passive in that they don’t need a power supply to carry out their basic function – http://www.electronics-tutorials.ws/resistor/potentiometer.html, and there are two main types of pot: linear and logarithmic.
In these, a wiper inside moves between the lugs and the resistance between the lugs is in proportion to the distance moved by the wiper. So if you turn a knob, the wiper move increases resistance, in exact proportion to the distance that your turn the knob. This inexpensive control is often found in lab setups.
With these pots, when the wiper moves between the lugs, the resistance is increased by a logarithmic function. In effect, the resistance element has a bias and to go back to the volume knob example, the middle of the turning distance is not half of the power of the potentiometer.
These are among the most widely used electrical control components in Ireland http://www.osmelectrical.com. They are widely found in audio electronics, being employed to produce the required volume control without having to use the whole range of the volume knob. You can turn the knob a small amount and the logarithmic effect will greatly increase the power of the circuit and therefore the volume.
Pre-set or ‘trimmer’ pots can be set so that occasional adjustments to a circuit are quick and simple. For example, calibration can be adjusted. You can also mount single turn, pre-set pots directly onto circuit boards.
Simple and easy to use, the handy potentiometer is found everywhere that current needs to be controlled.