Mar 062013
 

Analog computing in the dark!

I got interested in analog computers over the summer and ended up buying a Comdyna GP-6 off of eBay. They still make the GP-10 version and the Comdyna finds application in teaching labs and in control systems engineering. You can read about the history of the Comdyna GP-6 here.

The unit works and as a first computation I patched it up to simulate the Lorenz system.

The Lorenz system of ODEs is given by:

\frac{dx}{dt} = s (y-x)

\frac{dy}{dt} = r x-y-x z

\frac{dz}{dt} = x y - b z

The classic Lorenz butterfly results when s=10, r=28, and b=8/3.
Here’s the resulting program:

The “program” on the Comdyna GP-6.

And here are a few time-exposures of the program output.

The x-z plane of the phase space.

Another view of the x-z plane.

The x-y plane.

 

 Posted by at 6:01 PM

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