My new "automatic-wah"

[snoof]

A follow up to my post here...  http://www.diystompboxes.com/smfforum/index.php?topic=52154.0

I was looking for a "auto-wah", not in usual sense of the term (Mutron III type), but like a speed controllable tremolo, with wah instead of volume up-down.  After some suggestions from folks in the above thread, I came up with this...

I ended up building the LFO from the Tremulus Lune (http://www.tonepad.com/getFile.asp?id=84, or http://commonsound.org/tremulus/tremulusnewchem.jpg), and using it to drive an old Crybaby wah board converted to a "Resistor to ground" style wah using ideas at the GEO site (http://www.geofex.com/Article_Folders/wahpedl/wahped.htm).  I originally tried the LFO from the old Phozer from ROG (http://www.runoffgroove.com/phozer.png) which worked, but the slow was too fast, and the fast wasn't fast enough.  I made the LDR module by putting the LED and Photoresistor together in heat shrink tubing, as is used in many other ckts.  Works great, and has all the speeds covered!  The only prob was that with the 4558 chip, it ticked like crazy!  I got it to quiet down by filtering the PS with 1000u cap, but that seemed a little excessive.  So I swapped in some other op-amps I had, and settled on the LM358, as it was quiet w/ out the extreme filtering.  At the fast speeds, it sounds very gargly!!  Anyway, just thought I'd post this for anyone looking for a circuit like this...

Scott 

[petemoore]

  Excellent !!!
  I love reading about 'I whipped up a ...' and this looks like a good one!

[moosapotamus]

 

~ Charlie

[TELEFUNKON]

Congratz!

[slacker]

Good stuff, I like that kind of cut and paste approach. Any chance of some sound clips?

[snoof]

I hope to post a few when I get it in a proper box    It's got some RF issues right now...