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G3XSE > INFO 05.07.02 20:57l 17 Lines 808 Bytes #999 (0) @ WW
BID : 42392_GB7COS
Read: DB0FHN GUEST
Subj: carbon arc
Path: DB0FHN<DB0ZWI<DB0CHZ<OK0PKL<OK0PPL<RZ6HXA<SP7MGD<GB7YKS<GB7LGS<GB7NLW<
GB7WIG<GB7JYU<GB7COS
Sent: 020630/0920Z @:GB7COS.#31.GBR.EU #:42392 [Essex, Point Clear] FBB7.00g23
From: G3XSE@GB7COS.#31.GBR.EU
To : INFO@WW
When I was doing my HNC 30 years ago we were shown a carbon pile motor speed
control. Although thyristors were coming in, this was a device, consisting of
maybe 20 two inch square plates in series and a device which altered the
pressure on them, thereby changing the resistance. This was hooked up to
mains 240v and a motor. The lecturer then called a fag break and left the
room. A fellow student, who had seen this before, cut a one and nine tenths
bit of paper and inserted it between two plates.
After his fag, the lecturer turned on the power. It was an amazing display of
how a carbon arc worked. The display lasted a minute, then the piles worked
as expected. The paper burnt out thus comitting the perfect crime, self
destroying evidence.
73's de Hugh
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