Nonlinear Feedback Filter (idea only) schematic on the web

[Sean Costello]

Scott Gravenhorst wrote:
> 
> This is as yet untested, but I worked out a circuit I want to
> prototype and test.
> 
> http://members.xoom.com/chordman/NonlinearFeedbackFilter.html
> 
> Have a look if you like.

Looks cool.  One more idea for a nonlinear circuit: Dan Slater discusses
turning a state-variable circuit into a Ueda Attractor, using two
multipliers for an x to the 3rd function in the feedback loop.  I found
a circuit in Electronotes that is a nonselective frequency tripler, that
uses two transistors.  I can't do ASCIImatics, but I can describe it
pretty easily:

Use a 2N3904 and 2N3906.  The bases are tied together, and the input (+-
1.2 volts) is applied to the bases.  The emitter of the 2N3904 goes
through a 15K resistor to -15 volts, while the emitter of the 2N3906
goes through a 15K resistor to +15 volts.  The collectors of the two
transistors are connected, and the output (+_ 0.4 volts) is taken from
them.

Sean Costello