group buy for homebrew CPUs?
cclist at sydex.com
Sat Aug 12 17:29:28 CDT 2006
On 8/12/2006 at 3:02 PM Don wrote:
>Do they still use thermocouples (dirt cheap)? Or, have
>they moved on to things like infrared, etc.?
I've been out of that area too long. This was when I was a YOUNG man.
That was the day of mechanical chopper-stabilized vacuum-tube amplifiers,
some running from 25 Hz mains power. Heck, some places back then still had
key-wound chart recorders wtih clamp galvanometers. (Somehow, the word got
out that the galvanometer supports were gold, so we'd usually have to come
by a couple times a week and replace them). For some burner control, I do
recall some optical quartz-lensed thermopile heads, but they weren't
common. You checked accuracy of thermocouples with a hot-wire optical
pyrometer and calibrated instruments with a potentiometer bridge and a
thermometer (to measure the cold-junction temperature). Weston standard
cells were still in use.
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