just the auto not the wah...

[1878]

I have an old wah board with a Whipple inductor which I was hoping to make into an auto wah. Does anyone have any suggestions for the 'auto' circuit ?? I'm not looking at a load of features, but a switchable up/down sweep would be nice. I've already modded the board with bass, mid & treble pots as well as a switchable cap thingy & Q control.

I've got a couple of optoisolators knocking about as well as LDR's so that would be my preferred way of going about things.

Thanks in advance.

[Kipper4]

Take a look at the lfo in Dead Astronaughts Lightwah. It has a switchable ramp up/down sweep.
Search for it on the forum plus midwayfair did a version of it called the crying time.
I love mine.

[nocentelli]

OP - Do you mean an envelope detector ciruit that will respond to playing dynamics to trigger filtering provided by the inductor from an actual wah?

I can't think of an existing autowah circuit that uses an inductor to do the filtering part that you could adapt, but that's not to say it can't be done.

I would look at using something like the Meatball envelope filter that uses an opamp envelope detector to drive an LED (it also has and up/down sweep direction switch and attack + decay controls). You could use this LED (that varies in brightness with picking dynamics) tied to an LDR, and use the LDR to replace the pot in the orignal wah circuit.

[1878]

Basically, I'm looking for an LED/LDR combo in place of a pot to control the wah. I was thinking of using the envelope section of the uglyface to see if it worked before going onto something a bit more 'involved'.

[Mark Hammer]

OP - Do you mean an envelope detector ciruit that will respond to playing dynamics to trigger filtering provided by the inductor from an actual wah?

I can't think of an existing autowah circuit that uses an inductor to do the filtering part that you could adapt, but that's not to say it can't be done.

I would look at using something like the Meatball envelope filter that uses an opamp envelope detector to drive an LED (it also has and up/down sweep direction switch and attack + decay controls). You could use this LED (that varies in brightness with picking dynamics) tied to an LDR, and use the LDR to replace the pot in the orignal wah circuit.

The old Boss TW-1 used an inductor-based wah circuit, although it did not use LDRs to replace a pot, such as one would find in a standard Crybaby type.

[1878]

Just put the envelope section of the uglyface together with a DIY vactrol & it works !! Quite a bit of ripple though & it's only a down sweep. Still, it works.

[puretube]

the original wah-patent had an optional ldr in there, IIRC;
R.G. has a solution, too, IIRC... ( not here, though...)
maybe here...

[B Tremblay]

I collaborated with "culturejam" on the Quinoa in an effort to have an LFO-controlled inductor-based wah. It worked well enough, but I couldn't completely eradicate the pop when switching from LFO to manual sweep.  I can dig up sound clips and more info if there's interest.  It incorporates RG's LDR wah pot replacement as used in the Phozer. I'd probably do some things a bit differently now, based on conversations with Joe Gagan about the Boomerang.

An inductor-based wah with three control modes (LFO, envelope, and manual) has always seemed like a good idea to me.