My friend is using PD on an rpi as an effects processor for his guitar and has been trying out various simple distortion methods so I sat down and made a sigmoid abstraction for him with adjustable knee, kinda basic but nice sounding...

sigmoid~.pd
sigmoid~-help.pd

I am posting it here as I am curious as to what kinds of sigmoid solutions you guys have up your sleeve. So let's dedicate this thread to sharing homebrew sigmoids

@bocanegra Fun, I didn't know there was a name for that. Cyclone has tanh~ and overdrive~ in case you weren't aware.

I made something similar 5 years ago when I was experimenting with wavefolding. It's sort of like fractional recursion of the second half of cosine, if that makes any sense
deformPhasor~.pd
deformPhasor~ show.pd

Here's another one based on [log~]: logShaper~.pd

@jameslo - I am aware of the extended objects but I stick to vanilla for various reasons ([init~] is not loading here).

[cos~] provides a nice soft and smooth distortion for synth sounds- I use it a lot to beef up bass and snare etc, but usually only one pass and with a dry/wet crossfader to adjust amount. The way it's subtle also makes it good for exciter effects. Example:
exciter~.pd

You could of course change the filter, add more passes, try other sigmoids for the sound you want.

To stay on topic, here's a sigmoid based on the [pow~] object, using some convoluted math to allow asymmetric distortion curves (bias): pow-sigmoid~.pd