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cheapo inductors
Subject: cheapo inductors
Date: Wed, 14 May 1997 17:47:19 -0400
From: 104521.363-at-compuserve-dot-com
To: "INTERNET:tesla-at-pupman-dot-com" <tesla-at-pupman-dot-com>
all,
went to the local machine shop the other day. there i saw the brake
alignment lathe and the gallons of grindings under it and got an idea.
said grindings are mostly iron and steel as demonstrated by a magnet.
so,
i got a few quarts of the stuff for free (ok, ok, i got a 5 gallon
painters
bucket of the stuff which tipped the scales at 68 lbs) and mixed some of
it
into a hardening matrix (concrete == cheap) and spooned the resulting
glop
into several lengths of thick-wall pvc piping. Then i broke down and
went
to builders square and got several yards of the 1/8" ldpe tubing (12
cents/foot) and ran an awg 22 wire down the center (had no neon wire
handy
:-( ) and proceeded to wrap the pvc pipe with randomly spaced sections
a
la mark barton.
so what do i have? a large, but cheap inductor which can handle large
kick-back currents without a clear resonant fequency. yes, there will
be
eddy losses during the kick back and it will heat up due to the fact
that
the grindings are mostly in contact. but it is so large, the time
necessary it to heat appreciably is minimal. yes, it has lousy high
frequency characteristics as it is mostly iron filings and not an exotic
ferrite material and therefore it might saturate. but, again, it is
built
physically large so the necessary flux density would be huge. i suppose
i
could have gotten some 90 degree pvc connectors and made a closed loop
for
the magnetic flux, but this was a spur of the moment cheapo idea.
i haven't had problems with it being too much for the 15-90 neon bank
i'm
using at low power. when i get back from vacation, i'll take some
measurements. but, living in an apartment and having my tc on the
balcony
which faces other balconies necessitates discression on my part.
kyle