"Cheap Auto-wa" build report

[RickL]

I found it here: http://www.epanorama.net/schematicsforfree/Audio/Musical/Circuits/index.php

It's a little filter that can be either manually set or swept by a LFO. I added a dpdt centre-off switch to give three combinations of filter caps (the 10n caps connected to the collector of Q2). 4n7, 4n7 parallel 4n7 (9n4) and 4n7 parallel 15n (19n7). Built on perf, I managed to fit it onto a piece 10 holes by 14 holes. I didn't notice much difference when I fiddled with the 10k trim pot.

When swept manually it's a usable wah. You won't mistake it for a Clyde McCoy but as a fixed position wah it's not too bad. It might be worth building just the filter part, without the LFO, as an add-on to a simple fuzz.

Swept by the LFO it has a bit of a phaser vibe. If you've built a Phoser you'll have a pretty good idea of the sound.The Tune pot lets you alter the range of frequencies that are swept through. The cap selector that I added broadens this range out a bit.There's a pretty good range of speeds available from the LFO, more than I was expecting. I didn't notice too much ticking from the LFO unless the Tune pot was turned down fairly low.

If you've built enough fuzz boxes for a while and want to try a simple modulation effect this one is worth a try.

[Harry]

Interesting site!

Not meaning to highjack, but I once had a pdf for the "$2 fuzz" anyone know where that was posted?

[Mark Hammer]

If I'm not mistaken, that's the circuit that appeared in ETI several decades back, and was designed by Tony Allgood who eventually started up Oakley Spund Systems, purveyors of fine analog synth modules and some pretty super filters.

[reverberation66]

    I think he has the $3 fuzz posted here, seems like there are scans of the original article and everything, this is a GREAT site by the way for old school effects:  http://smg.photobucket.com/albums/v324/caseyseffectpage/

[reverberation66]

  Thanks RickL btw for the link there, tons of cool stuff on that one too, I'm thinking about that "pitch changer" already, never heard of the IC, have to look into that and see if you can still find 'em...

[gez]

I agree with your comments about using the filter for a fuzz - simple T filters make wonderful tone controls!

PS  Just a minor point, but for anyone who does build the LFO the 2u2 cap is the wrong polarity as shown.

[Harry]

    I think he has the $3 fuzz posted here, seems like there are scans of the original article and everything, this is a GREAT site by the way for old school effects:  http://smg.photobucket.com/albums/v324/caseyseffectpage/

No, no, that's not it I was looking for the $2 Fuzz, $3 is one dollar more than I'm willing to pay for my fuzz. THANKS!

[RickL]

PS  Just a minor point, but for anyone who does build the LFO the 2u2 cap is the wrong polarity as shown.

Oops, I meant to mention that. I changed it almost without thinking about it. It's the filter cap for Vb which isn't necessarily obvious the way the schematic is drawn.

OT how do I show who the quote was from when I put one in a post? I've been clicking the quote button then copying and pasting the quote between the quote and /quote.

[slacker]

OT how do I show who the quote was from when I put one in a post? I've been clicking the quote button then copying and pasting the quote between the quote and /quote.

you click the quote button that's next to the post you want to quote and it puts the author's name in for you.