A self-centering knob assembly comprising a back disk, a pair of rotary arms, a spring, and a circuit board fixed to the knob shaft, is provided, with the pair of rotary arms and spring disposed between the back disk and circuit board. Each rotary arm defines first and second slots at opposing ends and a center aperture therebetween that rotatably engages the knob shaft. The first slot engages the end stop pin to limit rotation of the rotary arm. The spring defines opposing arms that engage and oppose rotation of respective rotary arms of the pair. The circuit board includes circuitry configured to provide positioning data of the knob shaft, and including a drive pin that, for each rotary arm, engages and carries the second slot in a respective direction of an opposing direction when the knob shaft and thereby the circuit board is rotated in the respective direction.