Analysis of the Causes of Noise Generation in Potentiometers

A potentiometer is essentially a variable resistor. It derives its name from its circuit function: generating an output voltage that bears a fixed proportional relationship to the input (applied) voltage.

Dynamic Noise of Potentiometers When a sliding contact slides along the resistive element under applied voltage, the electrical noise generated is defined as the dynamic noise of the potentiometer. Dynamic noise is a key indicator of sliding noise. Its magnitude is related to shaft rotation speed, contact resistance between the wiper and resistive element, uneven resistivity of the resistive material, the number of sliding contacts, and the level of applied voltage.

Sliding noise is unique to potentiometers. When adjusting resistance, improper resistance layout, poor mechanical fit of the rotating mechanism, and inherent contact resistance cause fluctuating noise superimposed on the valid output signal as the wiper travels across the resistive surface. For wirewound potentiometers, noise sources extend beyond contact noise between wiper and windings, including resolution noise and short-circuit noise. Resolution noise arises from the stepped variation of resistance. Short-circuit noise occurs when the wiper bridges adjacent wire turns during movement; its amplitude is proportional to the winding current, resistance of individual turns, and contact resistance between wiper and windings.