[to_be_released]

As an electrical engineer, I often think about building effects pedals (although I still haven't gotten around to building any yet). While the more practical part of my brain thinks I should knock out a few simple clean boosts and drive pedals before taking on anything too crazy, there's an idea I have that I'd quite like to try at some point.

The idea is based largely on this circuit by Sebastian Tomczak: http://www.milkcrate.com.au/_other/s.../08_custom.gif, an eight stage custom waveform generator. Then I'd control the clock either by simply running the guitar into a schmitt trigger or perhaps using some form of digital pitch tracking. The schmitt trigger would only be feasible for single note stuff, and even then I'm not sure how feasible it would be. If it works, though, I should be able to get some curious sounds out of it.

Any thoughts from more experienced pedal builders?

[Rainer.]

Wow, translation for us mere humans?

[to_be_released]

Haha ok.

so the schmitt trigger would effectively make the guitar signal into a crude digital signal, switching between positive and ground at a frequency related to the note you're playing. That part would effectively decide the pitch of the output.

Then each time the output of the schmitt switches between positive and ground, it will make the wave shaper cycle through 8 different outputs. This effectively makes the waveform cycle through 8 different levels, chosen by what you set the 8 pots to. If all the levels were the same, no sound would come out. If the first four pots were maxed and the last four were zero, you'd get a square wave. More complicated waveforms could be created, with the limitation of it having to only use 8 stages.

I don't know if this helps, I might try to put together a better explanation later with some graphs. Graphs make everything better.

[Stratopastor]

.. so if I'm following you correctly, the output waveform will never (for example) look like a sine wave - the closest you could get would be like eight steps up and eight steps down again. Like 3-bit sampling... so it's always going sound somewhat fuzzy? In my imagination that's sounding like an early Moog set to go tzzzzzzzz.... Or have I missed the point?

[Rainer.]

Ooh, interesting. Would it work for chords?

[to_be_released]

Originally Posted by Stratopastor

.. so if I'm following you correctly, the output waveform will never (for example) look like a sine wave - the closest you could get would be like eight steps up and eight steps down again. Like 3-bit sampling... so it's always going sound somewhat fuzzy? In my imagination that's sounding like an early Moog set to go tzzzzzzzz.... Or have I missed the point?

That's exactly right. It would in no way preserve the tone of the guitar. Instead it turns it into a crude synth, with the note controlled by your guitar. It would be fun to then put it through a wah and some modulation effects.

If I were to want it to work with chords I would have to do it all in digital, I think, which would partially defeat the purpose. However, it could be possible to have a stage mixing the dry guitar signal with the craziness, which could be good.

[Stereotap]

Yeah, agree to that