potentiometers

A potentiometer is a three-terminal variable resistor that is typically used as a voltage divider to provide a controllable output voltage from a fixed input. It consists of a resistive element, a movable contact called a wiper, and end terminals at the ends of the resistive track. By turning a knob or moving a slider, the wiper slides along the track and taps off a variable fraction of the total resistance, producing a corresponding output voltage when used with a fixed supply.

In operation, one end terminal is usually connected to a fixed reference voltage and the other end to ground or another reference. The wiper provides a variable voltage between these two ends. If the potentiometer is used as a two-terminal device, it behaves as a variable resistor (rheostat); as a three-terminal device, it functions as a voltage divider. Potentiometers have power rating limits and mechanical life specifications based on the wiper contact and track material.

Tapers and formats vary. The most common tapers are linear, where resistance changes uniformly with rotation or travel, and logarithmic (audio) taper, where resistance changes more slowly at one end to suit human perception, such as for volume control. Pots come in rotary and linear slider formats, with single-turn or multi-turn designs. Trimmer potentiometers are compact, adjustable variants used for PCB-level calibration, while digital potentiometers are ICs that emulate pot behavior under digital control.

Applications are widespread, including volume and tone controls, user interfaces in instrumentation, calibration and gain setting in amplifiers, and as position sensors in certain control systems. Limitations include contact noise, drift over time, and wear of the resistive track, which can affect accuracy and lifespan.