ColorSound Sewing Machine Wah Pedal

[oldrocker]

I used a LED/LDR instead of a pot.  There's a lever inside that blocks or unblocks light as you step on it.  It works great too.
http://www.logmonster.com/images/full/?pic=d007d_1160300734-422-13888.jpg

[joecool85]

How did you use a LED/LDR setup in a wah?  Can we have some pics of the inside?  And maybe a schematic?  This thing is cool!

[oldrocker]

I used this Colorsound Wah schematic below and put the LED/LDR where the 100k pot is going to ground.  I also replaced the 33k resistor going to ground with a 50k pot for Q adjustment.  The pic isn't that great but it might give you an idea of the setup.  I'm going to work on some better pics of the LED/LDR mechanism.  It works great too.
http://www.logmonster.com/images/full/?pic=cswah_1162439148-422-14160.jpg
http://www.logmonster.com/images/full/?pic=DS0010ns_1162432918-422-14161.jpg

[joecool85]

Way cool!  So how does that get actuatted?

[oldrocker]

I put a diagram below that shows a flat lever in between the LED and LDR which blocks the light getting to the LDR.  When you step on the pedal the lever moves out unblocking the light from the LED gradually causing the wah effect.
If you look in the circle in the picture the black bar in the center is the lever.  The LDR is the white thing on the right and the LED is covered in black shrink tube on the left.
http://www.logmonster.com/images/full/?pic=Sewingped_1162536480-422-14165.jpg

[joecool85]

Aw, cool!  Sound clips and more pics would be appreciated, this sounds like a great idea.  I may yet be able to build myself a sweet wah pedal  :tu:

[oldrocker]

I'll have to try and get some more pics soon.  You can find a sound sample of the Colorsound Wah on my website.  I'm still working on it but check out sound samples of other pedals I've built.  I used a Blues Breaker I built as the distortion for the clip.
http://randallbarnett.homestead.com/SoundSamples.html

[joecool85]

The clips sound pretty good.  If you get any more I'd like to hear them, and I'll be looking forward to more pics.  I've never used a LED/LDR setup, so it could be a really interesting build for me.

[oldrocker]

You can get the parts at Radio Shack if you have one near you.  I bought a variety pack of LDR's and a variety pack of LED's.  I used the yellow LED's although red would work too.  The LED stays on all the time so you'll need to find a resisitor size that will make the LED shine nice and bright.  The shrink tube around the LED is to focus the LED light to one spot on the LDR about 3/4" away is good.  With the heel down or relaxed state the LED should be blocked.  When you press down (toe down) the light should be un-blocked to let the light hit the LDR.

[joecool85]

This is such a good idea because it is so much more simple than using a pot.

[oldrocker]

Yes you're right an LED/LDR is so much easier to make an actuator to block and unblock light then it is to roll a pot back and forth.  I made a Vox 847 too.  It sounds great.  I used a Radio Shack audio transformer for the inductor. (Info I got from the GEO website.)  But I need some way to roll a pot with this one and haven't come up with anything yet.

[chaosface]

I have an PR-7 valve guitar fx processor.  And it uses the same setup.  It has a clear piece of plastic that has a graded black and white dot matrix pattern on it.  As it moves back and forth more or less light gets to the receiver.  I thought it was a cool idea too.  BTW, yellow LED's are best to use with photoresistors.  They are picked up best.