Omnidrive diode multiplex?

[SnackmasterMusic]

Hello all!

I think the Omnidrive is conceptually clever, and want to add one more
mod to it, on top of the pre-clip filter mod suggested elsewhere...I would like
to add a pair of rotary switches to swap different diodes in and out. I think it would be fun to have Ge, Si, and about 6 different colors....One for each direction. The only thing I'm wondering is, would that be useful or just a bunch of gnarly crud? and also, would I have to tweak any other parts of the circuit to compensate?

Thanks,
http://myspace.com/snackmastermusic

p.s. my favorite distortion pedals are:
korg toneworks hyperdistortion 104ds
Rockman Distortion Generator (doesn't require input!)
Theremaniacs Harmonic Percolater clone

And I wish my friend would let me try his Hot Cake from New Zealand...
It sounds lovely...anyone have any idea what architecture it's using?

[Mark Hammer]

Have you tried an unmodded Omnidrive? While a nice little work of incredible flexibility (and I've made several), the sound is not all that inspiring to my ears, and not really worth the effort to mod extensively.

[SnackmasterMusic]

Hi, Mark!

No! I have not yet tried an unmodded OmniDrive, although my friend
and I just finished printing our OmniDrive boards with press and peel
blue. I'm waiting for them to etch now! My etchant is not heated, so it
takes a long time...around an hour! Hopefully next time he comes over,
we'll work on the boards some more.

Thank you for your reply and your heads up!

BTW, do you have a good source for DPDT stomp switches?

-Snackmaster

[Mark Hammer]

You don't have to heat ALL the etchant, although certainly a warm etchant bath works faster. Other alternatives to having a completely warm etchant bath include:

1) Floating the board face-down on the etchant and pointing a small desklap (e.g., a 20W halogen)at the back of the board from 4-6" away.

2) Using a heat gun or hair dryer and warming up the board from behind.

Any heat applied to the back of the board is transferred through the board to the etchant immediately in contact with the copper, speeding up the process. Once the reaction occurs, that etchant becomes heavier and falls away, sinking to the bottom, and leaving "unclaimed" ferric chloride molecules available near the copper. Don't heat the board too aggressively, but warming it up from behind WILL expedite the process.

If the board has been buffed to a shine and has no "finger juice" or other residue on it, the etch will also proceed faster and more evenly.

One useful tip is to drill small holes in each corner of the board before etching, and insert toothpick "legs" so that the board is assured of remaining on the top of the etchant bath no matter how aggressively you agitate or warm up the bath.