The expression pedal input on the Minifooger Ring controls the frequency of the ring modulator. Use an expression pedal for hands free control of the frequency knob.
Tip: Use the scalable output of an Moog EP3 expression pedal to set the Minifooger Ring to do octave switching. Tune the freq knob to the first octave with the EP3 in the heel position. Use the scale knob on the EP3 to tune the frequency of the ring mode in the toe position.