4Scroll3
Dwell Ch
Ian writes –

In making an electronic circuit exhibiting chaos, one is essentially making an analog computer for the differential equations describing the system. This means that circuits that can differentiate a voltage are needed. In practice, it is convenient to actually do this with electronic integrators, the idea being that the input of an integrator is the derivative of its output. In addition, a nonlinear circuit element must be incorporated, as linear systems cannot be chaotic.

Chaos theory schematic – [via] Link.