Inductor-less wah, check this out

[zener]

http://members.shaw.ca/roma/wah.html

I don't know if many have known this before. I found this one long ago but I only built this one today in a breadboard. The opamp is TL071 not TL072. I haven't put the LED and LDR in a shrink tube. The switch is normally-open  I just breadboard it to see if the LED will light and the LDR will react and produce a wah sound. I made some mod to it. I'm a newbie in electronics, I don't know if this mod makes any sense.

I followed the circuit and there's something seems to be wrong. First, i put off the lights as I  tested the circuit by using a flashlight over the LDR. It WAAAHHED! :twisted:   . I didn't put the switch yet, I just pull and plug the black wire from the battery snap. The LED slightly flashed upon plugging the wire, then it went to become a fixed barely visible light. I think the light off the LED will not be enough to drive the LDR, you can see it only in the dark. I tried reducing the RV1a and RV1 up to 100ohm both but nothing has change. Here's what I did:

I tried putting another 9v, positive going to GROUND and negative to the negative of 100uf. I remove the switch between the .1uf and 100Uf and just connected it. I put the switch between the negative of the new 9v and 100uf negative.

By doing so, the LED lit brightly as I plug the negative of the new 9v and it stayed bright. I pull the negative and the LED went off gradually. The RV2 determines how quickly the LED goes out. I think that's how it should be to emulate a pedal movement, right.

Sound-wise, I don't know if it's comparable to an inductor wah. I haven't heard a wah with inductor yet. But from what I heard, it really WAAAHHED. The site says it's Morley circuit and I read somewhere that Morley doesn't use pots.

Hope my mod makes any sense. I'm just glad to have it since it's difficult to have an inductor. Thanks Laurier Gendron :wink: