Letters A, B, C, and F on Potentiometers indicate relationship between slider position and resistance of potentiometer.
The relationship between slider position and resistance is also sometimes known as the “taper” or “law”. This relationship can be controlled during manufacture by changing the composition or thickness of the resistance coating along the resistance element.
Potentiometers made in Asia and the USA use following conventions:
- Letter A for logarithmic taper
- Letter B for linear taper
- Letter C for logarithmic taper (Though this is rarely used)
Potentiometers made in Europe are marked as follows:
- Letter A for linear taper
- Letter C or B for logarithmic taper
- Letter F for reverse logarithmic taper