Right, bit more information, an example patch and some sounds. sorry for the delay, have been having a reshuffle at home and the serge was out of action whilst it was relocated.
So firstly, Ian has gotten back to me, and is happy for me to distribute these as long as it's small numbers for people DIYing stuff. My plan is to sell them direct to people who DM me on here, and not putting them on pusherman/synthcube. In the unlikely event there's hundreds of requests then I guess I'll have a chat with him to sort something else out, but I don't really see that being the case because these feel pretty niche. Possibly I'd just create a version without the X(1-X^2) circuit to distribute but I think that's probably the most interesting thing on here.
Which brings me to the next thing. I've spent a bit of time this weekend getting to grips with these, using them in the driven double well example on Ian's site.
https://ijfritz.byethost4.com/Chaos/ch_cir1.htm
They're definitely a lot of fun, and there's interesting stuff that can be done with them, but it requires a very fine touch a lot of tweaking, and probably a scope. I find it difficult to not have one or both of the outputs slamming into the voltage rails whilst oscillating for example, and getting the nice double attractor images has proved pretty elusive so far. It's not clear to me how much of this is my patching, or requires more work, or if there's something fundamentally wrong with the design of these (I've not trimmed for or even thought about any DC offsets in the lm13700 outputs for example)
Of course none of this is necessarily a bad thing depending on your point of view, just that I think a lot of people interested in chaotic oscillators and signals may be better served by getting a complete ChaQuO/Hypster/etc module.
Anyway, with that in mind, have a patch and some sounds.
This is essentially the double well example.
Integrator A -> Integrator B -> Non-Linearity -> Mixer + Driving Oscillator -> Integrator A
The scaling buffer is being used for negative feedback/damping around Integrator B, as well as controlling the rate on both integrators simultaneously and letting it be modulated slightly by a triangle LFO from a cycling slope. The driving oscillator here was the variable sin/saw output from the CGS compact oscillator, with the volume control for that on the mixer corresponding to the drive control in Ian's circuit.
I should try to get some better images of the scope, but I was recording the sound at the same time and so was busy tweaking as well hah.
Recording as well, X output to the left channel and Y output to the right.
https://soundcloud.com/rumblesan/integrator-chaos
I'll periodically update here as well with other interesting things I find and patches I make using them. Might try patching up a state variable filter later and see how that goes.
Well done! 
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