[vcf-midatlantic] vacuum tube computers

David Gesswein djg at pdp8online.com
Mon Dec 4 19:49:54 EST 2017

On Mon, Dec 04, 2017 at 02:51:27PM -0500, Neil Cherry via vcf-midatlantic wrote:
> Would analog computers have be used in control systems where feed back would
> be use. I can't quite recall those classes anymore (I haven't needed them
> since the early 80's).
I think like all terms analog computer get fuzzy when you try to categorize
particular objects. Previously we were discussing more of general purpose
programmable analog computers which were used to model/solve problems.

I would call the analog proportional integral derivitive (PID) controllers
that were/are used a lot for process control analog computers. The PID
coefficents were normally adjustable for the particular application but
the general function implemented was not. I would not call just having feedback
an analog computer. An op-amp wired up as a unity gain follower has feedback
but I wouldn't call it an analog computer. V2 = V1 is a little too 
simple to call computing.

> Also my Calculus professor gave us an example of Calc used daily. I can't
> quite recall all of it but something like
> Acceleration
> Speed
> force
> I think that you can derive the next from the later. I'm sure there are
> other examples of where we actually use these formulas without realizing
> it.
Correct order
Speed/velocity (integral of acceleration)
Accelleration (acceleration = force/mass)

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