Boomerang Wah Questions

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stumper1:
I finally got back to my Boomerang Wah that I never got working.  I originally did my own layout using Paul's schematic.  I had issues I couldn't figure out so....etched another board using Paul's layout (Thanks!).  While removing parts from my old board and checking/testing them before putting them in the new board - I discovered that I had a bad (though brand new) inductor.  Replaced the inductor and it fired right up :).  Sounds great  - but I have 1 issue.

In the toe down position - the pot sounds noisy/scratchy.  It's only in the very last bit of rotation (about 2 1/2 teeth worth if that makes any sense).  I'm using a *ulltone 100k pot.  Tried a 200k wah pot and a 25kB alpha.  All three had the same issue.  Replaced all 3 electos on the board - no change.

I can adjust the pot to the point where it doesn't go that far - but I don't think I should have to.

Any ideas?

Thanks 8)

Arfman:
Quote from: stumper1 on September 22, 2007, 04:30:19 PM

I finally got back to my Boomerang Wah that I never got working.  I originally did my own layout using Paul's schematic.  I had issues I couldn't figure out so....etched another board using Paul's layout (Thanks!).  While removing parts from my old board and checking/testing them before putting them in the new board - I discovered that I had a bad (though brand new) inductor.  Replaced the inductor and it fired right up :).  Sounds great  - but I have 1 issue.

In the toe down position - the pot sounds noisy/scratchy.  It's only in the very last bit of rotation (about 2 1/2 teeth worth if that makes any sense).  I'm using a *ulltone 100k pot.  Tried a 200k wah pot and a 25kB alpha.  All three had the same issue.  Replaced all 3 electos on the board - no change.

I can adjust the pot to the point where it doesn't go that far - but I don't think I should have to.

Any ideas?

Thanks 8)


I just modified a guys wah pedal. I got the info from Geo Technology of the Wah pedal, specifically the LDR mod mentioned that was by Craig Anderton. I didn't get it working with a LDR, it worked but there was a perceptible delay from hi to low as the LDR went dark, but I ended up going to RadioShack and getting an Infrared LED/Phototransistor pair (same package)...I had to rebias the LED part of it but it worked great! No scratch whatsoever...

One issue though is that LED draws 100ma so it's a battery killer...you'll want to use a power supply...

stumper1:
Arfman,

Thanks for the tip - I'll look into it.  The thing that has me wondering is that I tried 3 different pots - all brand new - and they do the same thing.

Paul Marossy:
Quote

The thing that has me wondering is that I tried 3 different pots - all brand new - and they do the same thing.

Yeah, I am wondering about that, too.  :icon_confused:

B Tremblay:
Which schematic did you use?  IIRC, Paul had two at his site.  I know that I started with one and it wasn't quite to my liking, so I modified it and came up with this:

http://www.diystompboxes.com/smfforum/index.php?topic=52412.msg396085#msg396085

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