IEC 60190: Non-Wirewound Potentiometers — From Radio Knobs to Industrial Position Sensors

Non-Wirewound Potentiometers: From Radio Volume Knobs to Industrial Position Sensors

IEC 60190 specifies non-wirewound potentiometer requirements. Despite ubiquitous digital control, potentiometers remain essential in human-machine interfaces (volume knobs, dimmers) and position sensing (servo feedback, accelerator pedal position) — because their absolute position memory is something digital encoders cannot provide without power.

Key characteristics: (1) Resistance taper — linear (B), logarithmic/Audio (A), inverse-log (C). Wrong taper choice means a volume knob has almost no adjustment range at low volume. (2) Sliding noise — carbon-track potentiometers develop increasing contact resistance fluctuation with age, introducing audible “scratchiness” in high-impedance circuits. (3) Power derating — a potentiometer used as a voltage divider (not a rheostat) must be derated to 10–20% of nominal power, because only part of the resistance element carries current.

TN Lab — The potentiometer is one of the simplest analog sensors. Its selection still demands engineering attention.