octaver for Bass guitar

ok, so basicly what i want to do is build a foot pedal that works kind of how a wah pedal does for a guitar in the sence that the physcal structure of the pedal is using the treadle style of pedal, rather then a stomp box, but instead of it making a wah sound, i want it to take the pitch of my bass down an octave. if tried a few octave pedals for my bass but the original signal still underlies the - 1 oct sound that i get, the only one iv been happy with has been the digitech whammy (but its far too expensive). i am hoping that i can have the output sound of the pedal i make when the pedal is in the toe down position will not have the underlying sound of the original signal, but also bring the pitch back up to unison when in toe up position.

i dont know where to begin, can i please have some help on this?

Hi

I'm wondering if you might be able to adapt the principles of this Adafruit voice changer project to this? The article does say you won't be able to sample the potentiometer (in this case in the pedal) and playback the audio in real time, but if you test it you might find the pedal sample rate that's possible might be perfectly acceptable.

I'm pretty sure the method & theory will be useful reading in any case.

Cheers ! Geoff