Soon after the rise in popularity of the original Fuzz Factory, the Fuzz Probe was introduced. This version kept most of the circuitry the same, but added a voltage-sensitive copper plate affixed to, and extending downward from the bottom of the unit. This copper plate, hardwired to the 'Stab' control on the pedal, allowed for real time control by use of one's foot or hand. By varying the distance from appendage to plate, the self-oscillation effects of the Fuzz Factory (Probe) circuit could be tempered and played musically, similar to a Theremin.