This is the "House Pedal" - an overdriver/distortion/fuzz/octave up pedal. It functions as a simplified Electro-Harmonix "Hot Tubes". No opamps, just a standard 1-FET booster to drive the CMOS inverters. Overdriven CMOS inverters actually sound a bit like a tube guitar amp, moreso than most opamp diode clipper circuits. I think. It's all the mind anyway.

A lot of distortion and volume from this thing, and I've reduced the gain from R.G. Keen's "Hot Tubes" schematic.  I don't think the EH Hot Tubes was this hot (The opamps didn't give much gain, this may be the reason). The EH Hot Tubes is a guitar amp simulator. You have 2 inverting assymetrical clipping stages, a tone control and a symmetricial clipping stage. This is a crude model of a push-pull guitar amp.

C. Gardel pointed out that the 22uF cap was in the wrong place so I fixed that. One end went directly to 9V and was making things fuzzier.

It does seem that the manufacturer of the CD4049UBE chip used makes a big difference. It's worth trying a couple of manufacturers. Harris (CD4049UBE H9801) and ST Microelectronics (HCF4049UBE W990A9828 MALAYSIA) work for me. You can replace the input transistor with your favourite volume booster, a tube screamer, or an opamp as in the Guitar Player Anderton Tube Sound Fuzz. It does actually sound a bit like an overdriven tube amp.

This is what I'm currently using though, it has more control over gain, and a little more high frequency taming. It gives an octave up effect when you turn the Gain/Octave control to zero, and Oscillation (with a hard-to-control Octave down synth effect) when you turn everything up to max, so take it easy guys:

This is an even simpler version: Basic Hot Harmonics

This is beginning to look like the Anderton Mk II. ( Craig Andeton's Tube Sound Fuzz , remove the boost from Craig's circuit, and you have the Red Llama) The pickup loads the input, reducing high frequencies (which is good). Turning the volume control down to about 7 takes nearly all the distortion away, giving a bright rhythn guitar sound. See also the Slow Finger on Aron Nelson's page.

References (Nearly all of these links are broken, google them ):