Craig Anderton's Wah/Anti-wah

[aelling]

This one seems interesting. There seems to be two different schematics, one for +18v and one for +9v.


+18v version
http://4.bp.blogspot.com/-4Bb05WGylYQ/T8JMJalGvnI/AAAAAAAAATI/iDypE3toKVY/s1600/wah2.gif

+9v version
http://electro-music.com/forum/phpbb-files/thumbs/t_wah_672.png

[jaredcohen]

Drew the 9v version up tonight. Haven't verified it. For Cx and Cn you're obviously going to want to socket those until you find the pair you want. Let me know if it works.

[aelling]

Thanks alot Jared, I forgot I requested this but I just build it and the layout works fine.

However, this circuit could use some tweaking, there's a high pitch oscillation when pot is fully cw using 22nF's, perhaps a cap between pot 2 and ground? It maybe also need a little more volume, perhaps different value on the 10k output resistor?

Anyway, thanks again for the layout, it works, but one should definitely play around a little with this one to get it to properly work.

[jaredcohen]

I think he recommends using pairs of caps between 1-5nf. So the 22nf cap could be causing unexpected behavior for sure.

[aelling]

jaredcohen wrote

I think he recommends using pairs of caps between 1-5nf. So the 22nf cap could be causing unexpected behavior for sure.

Ooops, you're right, I didn't convert the values properly. I´ll try the correct values tomorrow. Thanks

[aelling]

Okay, so I made the changes using a pair 1nF's and 4.7nF's and it works without that oscillation. The volume problem I think is more that you loose certain frequencies and overall beefness with a wah rather than a unity gain problem, which it does reach unity.

So your layout is verified. Thanks