They are often referred to as instrument knobs, electronic knobs, or electrical knobs. Control knobs providemachines or instrumentswith precise position adjustments and controlled levels of circular motion,A potentiometer knob isan accessory that is used as a control knob for a potentiometer. How do they work? Many potentiometers knobs are simply push on and can easily be fitted to the potentiometer shaft. Others use a fixing such as a nut, grub screw or blind set screw to fix them in place