Morula Auto Wah

Here's a simple auto wah circuit with a pretty low parts count I thought was interesting. Not a lot out there on it, but it uses a single CD4049UBE to create an LFO and wah audio path. The depth of the effect is controlled by the LFO. Should fit nicely in a 1590B. Here's the schematic for reference.

Mad Professor Snow White AutoWah

Happy New Year, everybody! I hope this year brings you all joy and much soldering. :)

By popular demand, I give you the Mad Professor Snow White AutoWah. Now stop pestering me for it. ;) This was a pretty complicated circuit to fit on a single-sided board, so there are a few jumpers (one of which is super long–bugs me, but it was the only way to make it work), but if you play your cards right you should be able to squeeze it into a 1590B like the original.

Seamoon Funk Machine

The Funk Machine is a filter effect that can be used on either bass or guitar (or synth, Rhodes, harmonica, etc). It's also like an auto wah, given that the wah effect is controlled by the string attack of the player. Original units used 2, LM741 chips, but I've laid it out for an LM1458 (which is 2, 741 in a dual op amp). Don't try to use a TL072 or JRC4558, as they will not work in the circuit. Check out the discussion of this circuit over on Tagboard Effects for more info.

DOD FX25 Envelope Filter

The FX25 was initially produced by DOD in the early 80s and is an OTA-based envelope filter/auto-wah. It's a fairly tweakable and you can find various mods on other sites, but this is for the stock layout. The original switching circuitry has been removed, so you can use true-bypass. An LM1458 is listed in the layout below, but just about any dual op-amp should work there (TL072, NE5532, JRC4558, etc.), so if you get a little distortion, try a different op-amp.

Update Aug. 10, 2016:

I've fixed the layout as per NapAlpha and Eduardo's comments below. Thanks for catching that guys. Sorry it took me so long to make the fix.