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Another Inductorless Wah, now with Sallen-Key filter

Started by thomasha, August 22, 2017, 04:28:03 PM

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That's really really cool!

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Partner and Product Developer at Function f(x).
My Personal Site with Effects Projects


Wonderful job as usual, Thomasha!

I'll give it a go as soon as I have the time.
Little question though, is R10 really a 1 ohm resistor?




R10 is a 1 ohm resistor, but you can use a jumper.
The thing is that if you put a 1k potentiometer there you can change the Q frequency.
The resistor is there so I could tweak the circuit, but in the end it sounded better with the pot. shorted


So I guess the BOTY contest this year is just for runner-up positions. ;D

Awesome build!


Made one, also in a 1590ish enclosure. Sounds great!. :D
All the components are from Tayda. Tayda's LDR (they only sell one type) resistance goes from ~0.9kOhm to ~1.5MOhm using an "ultra bright" white LED.
Thank you Tomasha!.

Addy Bart

Quote from: thomasha on August 22, 2017, 04:28:03 PM
Hi guys!
Have another cool project for you.
The guy over
came with this idea and presented all the simulations and results.

If you remember, I built a colorsound wah, but it wasn't that intense as the other circuits that do use an inductor.
So I gave it a try, and now here is the result>

It really sounds better than the colorsound wah. I still need to make a comparison video, but until then, here is a short video of it. I'm still learning how to control a wah, for the second time...

Hope you like it!
I made a small file for it, but it's not as good as the madbean documents.


That's amazing. I'd love a wah that size.



Hi, i'm Lucas, this is my first post.

First, congrats for the project and the buldings, are amazing.

Now, I built a colorsound twin T wah and even though it sounded good, it wasn't what I was looking for.

So I decided to try this wah, which looks awesome, the sound and the project.

But the first step was the first problem, in my city I can't get the 2N5457 MOSFET.

When I looked at the place in the schematic, it's in the input buffer (I'm not expert in electronics, only a youtube viewer jeje, so probably I'm wrong  ;D)

Finally, my question, can I change the input buffer without changes in the final wah sound? How can I calculate it if possible?

Regards, hoping help


That looks amazing.  I love the etching.  I've never seen a wah build in anything but a wah shell.  I understand that it's an led/lrd combo for the wah sound but how exactly is it attached to the treadle.  If I can understand how you built the enclosure I can foresee myself making a small buffered volume pedal. 

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Under the lid is a thin aluminium sheet, where everything is screwed to, so that it would not ruin the top etch. There I fixed another thin piece of aluminium which enters the box right between the LED and LDR. It is more visible in my first wah, where a plastic piece was fixed with a small wire.

Here you find more pictures:

Regarding the previous question, another fet would be the J201, but this one is even worse to find. A better approach would be to redesign the gain stage with a simple transistor.
There is also a schematic with an OpAmp here
But will require a new layout.