Diddling with things for possible future videos. I think I can make an example of a Chua's circuit using a motor with attached pendulum for the tank -- hence the oddball component values.
Shove it into LTSpice, run it, and you should see some classical chaotic behavior. Here's a pic of the phase-plane; the axes are labeled, although you may have to squint to see them.
A shout-out to Jim Thompson for his atan(x) idea for making smooth transitions -- it certainly seems to work nicely here for the nonlinear element.
Version 4 SHEET 1 976 680 WIRE 48 96 16 96 WIRE 112 96 48 96 WIRE 176 96 112 96 WIRE 320 96 256 96 WIRE 368 96 320 96 WIRE 448 96 368 96 WIRE 16 128 16 96 WIRE 448 128 448 96 WIRE 112 144 112 96 WIRE 320 144 320 96 WIRE 16 240 16 208 WIRE 112 240 112 208 WIRE 320 240 320 208 WIRE 448 240 448 208 FLAG 16 240 0 FLAG 112 240 0 FLAG 320 240 0 FLAG 48 96 Vvel FLAG 368 96 Vctrl FLAG 448 240 0 SYMBOL cap 96 144 R0 SYMATTR InstName C1 SYMATTR Value 1600m SYMBOL cap 304 144 R0 SYMATTR InstName C2 SYMATTR Value 100m SYMBOL ind 32 112 M0 SYMATTR InstName L1 SYMATTR Value 16m SYMBOL res 272 80 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R1 SYMATTR Value 500m SYMBOL bi2 448 128 R0 SYMATTR InstName B1 SYMATTR Value I=0.1 * (50 * atan(V(vctrl)) + V(vctrl)) TEXT -22 280 Left 2 !.tran 1000 TEXT -24 304 Left 2 !.ic V(Vvel)=16m TEXT -24 328 Left 2 !.ic I(L1)=0 TEXT -24 8 Left 2 ;An example of Chua's circuit, showing chaotic behavior.