I use a rotator, a magnet, and two buttons. The magnet just serves as a detailed knob (not a magnet). The rotator and magnet are just for show. The two buttons increase and decrease the value of the "knob".

Play around with the control base and see what happens

@U2 oh then I stand corrected.

@Sm10684 I've used a spitfire that had little knob that turned

Theoretically I think it should be possible through some (ab)use of the control base, but I'm not sure how.

You probably can’t