EHX Soul Preacher Nano.

W/ box. Note the misprint on the front, showing the pedal having one knob instead of two.

THE MOD: when using the manufacturer intended power supply input at the 'top' of the pedal, the pedal functions totally normally. When power is provided to the pedal via the yellow input (next to the 1/4in input jack,) voltage to the pedal will be controllable by the knob at the bottom of the pedal. When turned fully to the right, the pedal receives full voltage and operates as normal. As the knob is turned counterclockwise volume the circuit will stop passing input from the instrument (unless in bypass) and the pedal will begin to act as an oscillator. Further rotation of the knob counterclockwise will change the pitch of the tones produced until the knob is fully to the left and the pedal will not pass or produce signal unless in bypass. DO NOT plug two power supplies into both power inputs at the same time, only one or the other as that could damage the circuit, use only one or the other.

I have not seen any others like this one. I don't really want to part with it.