[AH] CV/audio mixer for modular idea

[Phillip L. Harbison]

Ken wrote:
> [...] Instead of a whole pile of digital stuff the two axis
> rotation became a very simple analogue circuit that switched
> polarity and mixed voltages.

This reminds me of a humbling but educational experience early
in my career.  I had just graduated with a BSEE (digital option)
so I was convinced that computers were the solution to every
problem.  I was visiting McMorrow Labs, a giant simulations lab
at Redstone Arsenal in Huntsville, AL.  We had just toured the
computer portion of the lab which featured a CDC-7600.  At that
time, this was the fastest supercomputer.  The cabinets were
arranged in a horseshoe so you could walk inside and view the
circuitry.  I was understandably impressed.

The next stop on the tour was what a modular synth lover would
call "analog heaven".  Imagine a room the size of a basketball
court completely filled with row after row of analog computers.
I grimaced and said something remarkably stupid like "Why would
you need all these dinosaurs when you've got that supercomputer
downstairs?"  The guide patiently explained that while the 7600
was a capable number-cruncher, the computations required to
solve even a single differential equation would occupy most of
the CPU's time.  In contrast, a small and relatively inexpensive
analog computer could solve a complex DE instantaneously and
produce a continuous output!

In fact, this bay was the heart of most simulations with dozens
of analog computers solving hundreds of DE's.  The CDC-7600's
primary duties were interfacing with the analog computers (lots
of ADCs and DACs), logging the data, and making some "non-linear"
decisions that are best done in the digital realm.  It also ran
a FORTRAN program that read DE's and generated patch diagrams.
In other words, the supercomputer was just a "lackey" for those
"dinosaur" analog computers.

As I labored to remove my foot from my mouth, I contemplated the
lesson of the day.  Keep an open mind and expand your toolbox.
If all you have is a hammer, every problem looks like a nail!


--
*name: Phil Harbison
*path: alvitar at traveller.com
*URL: http://www.hsv.tis.net/~alvitar