My return to Classic Cmp - San Diego, software archive, etc.
cclist at sydex.com
Thu Dec 18 11:19:03 CST 2008
On 18 Dec 2008 at 6:05, Dave McGuire wrote:
> Yow...What was the application? I'm familiar with those Honeywell
> CV supplies; they're nowhere near as stable as a Weston cell. Far,
> far, FAR more rugged though, and resilient to temperature
> shifts...which Weston cells are not.
Almost all were for process temperature control--from ingot soaking
pits to solutions on the continuous galvanizing line. "Rugged" was
probably more important than "stable", but I think it was more to
avoid the issue of once-monthly replacement of dry cells and
maintenance of the associated calibration mechanism. The big square
black 1.5v cells (made by National Union?) were used extensively,
instead of the smaller round No. 6 ones. On an open mill floor,
temperatures could go from sub-freezing to Saharan. Dirt, of course,
Right about this time, I recall that IBM had installed a computer for
process control in one of the new plants. Sadly, I don't recall any
details. Perhaps a 1710 used with the BOF.
Like a lot of American heavy industrial operations of the time, the
mill was a wild mix of period technology, much of it pre-war and much
running from 25 Hz power. Up until that computer, it seems to me
that the most sophisticated stuff was pneumatic--full analog
computers, with P-V and V-P converters, pneumatic amplifiers, square-
root extractors, differentiators, integrators, etc. "Wiring" done
with quarter-inch copper tubing and compression fittings. If the air
supply was kept clean, the pneumatics were pretty much
Earlier controls were mostly hydrostatic types of the diaphragm-and-
jet type. Keep the tank filled with Pydraul and you were good for
decades. There were very few electrical-only process control
systems, mostly restricted to non-critical processes.
(I hope there's enough "computer" content here not to irritate)
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