gyrator wah

[strungout]

Oy.

I had some time to kill, and put this together:

I like how it sounds and its a pretty simple build. It--eventually--came to me that I could probably get it to notch as well, by connecting the wiper of a pot to the 33n cap and stringing it across the "+" and "-" inputs...but all I get on the "+" input is a drop in volume, no wah. Any suggestions? Maybe I just need a hotter signal?

This is just for fun anyway.

Ciao.

[R.G.]

Although that circuit looks like the typical "across the inputs" EQ circuit, they are not similar enough to work as you suggest. Different operational principles.

Although they're not a direct answer to your question, for background on why this is so, read both of "The Technology of Wah Pedals" and "Simple, Easy Graphic and Parametric EQs" at GEO.

http://geofex.com/Article_Folders/wahpedl/wahped.htm
http://geofex.com/Article_Folders/EQs/paramet.htm

[strungout]

Ok, I'll have a look at those.

Thnx!

[Transmogrifox]

In the schematic it looks like the LED is in backwards.  Obviously, if the wah works, you put the LED in correctly in your circuit---just thought I'd make a note of that in the event somebody else builds it.

If you get the enough Q in the notch (it only takes a Q of 1), and a a depth of more than 20dB, then the filter will generate a nice little subtle swish, phase chorus sound.

Check out this concept for ideas:  

www.geocities.com/transmogrifox/haha

and for some audio samples:

http://www.geocities.com/transmogrifox/hawaudio.html


If your wah works as a wah, then put an inverting unity output on it, then connect it according to the HawaH circuit.  Replace the 500k resistor on the input of the inverting op amp stage with a 500k pot in series with a 10k resistor to increase the Q.  I think you should be able to adjust it from very subtle to where the circuit goes unstable and oscillates.

[strungout]

Oy.

Transmogrifox:

I fixed the schematic, thnx for pointing it out. I liked the clips, but I haven't got around to trying the stuff you mentioned yet. I decided I needed to finish some other projects first. They feel left out : P

Ciao.