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Vintage threads from the first ten years

Wah pedal circuits

8/26/1998 3:16 AM
Hamish	Wah pedal circuits Does anyone have a circuit for a wah pedal that does not involve a 500mH inductor? I have managed to find about five that do involve this part, which I can source but it would take two weeks and cost me a total of $US20 to have it delivered to New Zealand. I built one circuit using a design from a book which sounded lame (filter parameters all wrong). If anyone has a halfway decent schematic for a wah pedal based on an active filter instead of an inductor, I'd be very grateful. My email address is: ode@ihug.co.nz Thanks, Hamish

8/26/1998 3:16 AM

Hamish

Wah pedal circuits

Does anyone have a circuit for a wah pedal
that does not involve a 500mH inductor?

I have managed to find about five that
do involve this part, which I can source
but it would take two weeks and cost me
a total of $US20 to have it delivered to
New Zealand.

I built one circuit using a design from a book
which sounded lame (filter parameters all wrong). If anyone has a halfway
decent schematic for a wah pedal based on
an active filter instead of an inductor,
I'd be very grateful. My email address is:
ode@ihug.co.nz

Thanks,
Hamish

8/26/1998 6:26 AM
Preben Hansen	Hi Hamish. Try Stellans site. He has a section for his home build rack. In this rack is a VCF. As Stellan says "you can wah your brains out". There is a schematic and a sound sample too. Nice sound I think. Regards, and happy building. Preben.

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8/27/1998 5:45 AM
paul perry	Hamish, seeing you are in NZ, the latest copy of Silicon Chip mag (sept 98) has a wah as its lead (no pun intended) article. Uses a 4046 as a voltage controlled oscillator, which goes to a MF5CN switched capacitor filter. Nary an inductor to be seen. A good feature is that the Q of the filter can be tweaked by the ratio of 2 resistors. The only unfortunate thing is their plans for a pedal assembly, with a metal plate scraping around and forcing a linear pot back and foward. Yeah, right, OK for an hour maybe. Use a linear hall efect device & a magnet. The UGN3503 is easy to get, it's used in the gear change indicator elsewhere in this issue.

8/27/1998 5:45 AM

paul perry
email

Hamish, seeing you are in NZ, the latest copy of Silicon Chip mag (sept 98) has a wah as its lead (no pun intended) article. Uses a 4046 as a voltage controlled oscillator, which goes to a MF5CN switched capacitor filter. Nary an inductor to be seen. A good feature is that the Q of the filter can be tweaked by the ratio of 2 resistors.
The only unfortunate thing is their plans for a pedal assembly, with a metal plate scraping around and forcing a linear pot back and foward. Yeah, right, OK for an hour maybe.
Use a linear hall efect device & a magnet.
The UGN3503 is easy to get, it's used in the gear change indicator elsewhere in this issue.

8/27/1998 5:58 AM
paul perry	Another approach is that in one of Penfold's books of guitar effects, "Advanced Projects for Electric Guitar"ISBN 0.85934.380.4 where a hall effect device UGN3503U (Ungar) changes the apparent resistance of a fet.

8/27/1998 4:17 PM
Hamish	Thanks - it's ironic, that the magazine is on the newsstands while I am searching the internet for a circuit. Anyway, I build the wah out of the first Penfold guitar FX books and it sounds horrible. FWIW I am using an old Vox volume pedal as the mechanism. A hall effect sensor would be better, but I am halfway through building the wah from Stallan's (sp?) site. Thanks for the leads though, I have another wah to build for someone else and I might try one of those circuits. Cheers, Hamish

8/27/1998 4:17 PM

Hamish

Thanks - it's ironic, that the magazine is
on the newsstands while I am searching the
internet for a circuit. Anyway, I build the
wah out of the first Penfold guitar FX books
and it sounds horrible. FWIW I am using an
old Vox volume pedal as the mechanism.
A hall effect sensor would be better, but
I am halfway through building the wah from
Stallan's (sp?) site. Thanks for the leads
though, I have another wah to build for
someone else and I might try one of those
circuits.

Cheers,
Hamish

8/28/1998 6:20 AM
paul perry	Thanks for telling us the Penfold wah sounds shitful. Mr Penfold has done some terrible things, notably his book on building your own analog synth, almost every ckt has a fatal error just for starters! Be sure to let us know how Stellan's one goes

8/31/1998 4:46 AM
Hamish	I may have to reserve that opinion against the Penfold wah. When I was dismantling it for parts to make Stellan's wah I discovered I had not soldered a joint on one of the resistors that is used to bias the input signal to one of the opamp stages, since the circuit does not have a -ve. Also, I found the cct you mentioned that uses the hall effect device. (Almost finished the new Wah, has the disadvantage of running two 9V batteries, my design expertise does not extend to changing that). I have an original Vox volume pedal. I'm thinking of using it as a template and casting some copies in aluminium, to use as volume/wah/whatever. That might be a few months from now, if anyone is interested feel free to email me.

8/31/1998 4:46 AM

Hamish

I may have to reserve that opinion against
the Penfold wah. When I was dismantling it
for parts to make Stellan's wah I discovered
I had not soldered a joint on one of the
resistors that is used to bias the input
signal to one of the opamp stages, since
the circuit does not have a -ve. Also,
I found the cct you mentioned that uses the
hall effect device. (Almost finished the
new Wah, has the disadvantage of running
two 9V batteries, my design expertise does
not extend to changing that).

I have an original Vox volume pedal. I'm
thinking of using it as a template and
casting some copies in aluminium, to use
as volume/wah/whatever. That might
be a few months from now, if anyone is
interested feel free to email me.

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