[sdiy] Static ADC and DAC recommendations?

[Phillip Harbison]

m brandenberg wrote:
> Phillip Harbison wrote:
> > The professor who taught control theory at UAH did the
> > control theory work for the Saturn V rockets using an
> > array of analog computers and an IBM 1401.
>
> Would love to read more on that.

His name is Dr. Carroll Johnson. He was a graduate of Purdue.
Someone told me he was the #2 control theory man in the USA.
When I asked the obvious question (Who is #1?) that answer
was "the guy who taught him at Purdue". I would guess he is
now in his late 70's or early 80's if he's still alive.

> I'm always amazed at the  gimballing F1 engines and the tiny,
> tiny little system making  that work and work correctly. That
> was some first-rate engineering.

It's amazing the Apollo/SaturnV went to the moon and back with
less computing power than in a modern programmable calculator.
My uncle worked on the computers for the space shuttle. Those
were about 1000 times more advanced.

I always enjoy looking at how engineers solved complex problems
in an age prior to VLSI. That IBM 1401 (not absolutely sure I
have the right model number, but definitely pre-360) had a
novel solution to power conditioning. It was an electric motor,
a generator, and a HUGE flywheel on one shaft. It was not a
UPS by any stretch, but the flywheel had enough inertia to ride
out a power glitch.

I looked at a much older IBM design using vacuum tubes. It used
a rotating drum to store its REGISTERS. Can you imagine how slow
that would be? I guess when the cost of a flip-flop is at least
one (probably 2) vacuum tubes, you do everything you can to
reduce the amount of state kept in the CPU.

Someone mentioned the 10-turn pots common on the analog computers.
I forgot to mention those. The pots were of the Vernier variety
much like this example.

http://www.ace4parts.com/images/products/503-0004_medium.jpg

There were hundreds of these spread over about 30 computers. It
is a shame there were not salvaged. Usually when equipment was
sold for salvage the buyers were only interested in the copper
and gold. *sigh*

It annoys me when younger coworkers do not respect the work of
engineers from the "distant" past. How do you know where you are
going if you cannot appreciate where you've been?

-- 
Phil Harbison   <---- almost a fossil