[sdiy] Analog computers

[Tim Ressel]

Yo,

All this talk of strange attractor (ex-wife?) and
chaos engines (offspring??) got me to thinking: what
about an Analog Computer? Something that is patchable,
configurable, and otherwise delta-ish. I could dig a
box like that. Maybe I have finally found a use for my
mini-suitcase...

An analog computer is basically some integrators,
multipliers, and lots of precision 10-turn pots with
counter dials. I know, i know, there is more to it.
But for our purposes we can ignore some of the issues
like initial conditions and integrator scaling.

Ah, but those 10-turn dial pots cost a fortune. Even
surplus they cost a bunch. Then I had this idea:
instead of pots use multiplying DACs. For example I
have AD7225s laying around. they are quad 8-bit
M-DACs. If i use two of the dacs to make a course-fine
arrangement I can get two 'pots' out of one package.
throw in an AVR processor, some cheap rotary encoders,
and some cheap displays, I can have precision pots
without paying $25 each.

--tr



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