Autowah Tone Modding?

[Arn C.]

Thank you for your response.   I will try a few variations of this to find out what works best!

Peace!
Arn C.

[slacker]

I still don't get what the NAND gates are doing, but to answer Snap's question:

The first 2 4001 gates (pins 1 to 6) are a square wave LFO and the other 2 are buffers, one output then feeds an LED as a rate indicator and the other output feeds the base of the bottom transistor, which like you said is a VCR. When the high output of the LFO hits the 47u cap it starts charging up and the voltage on the base of the bottom transistor ramps up. When the LFO output goes low the 1n4148 diode prevents the base of the transistor going instantly low as it is reverse biased and won't conduct. The 47u cap then discharges and the voltage ramps down, so you get a roughly triangular sweep.

[earthtonesaudio]

Thanks slacker,
I guess I kind of already got that much, so maybe what I am missing is what the effect does.  From both the circuit and your description, it sounds like a wah that has a regular sweep set by the speed of the LFO.  When I think of an "autowah" I think of an envelope filter, that responds to playing dynamics.  Maybe "autowah" means different things to different people.