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Re: Toroid size on Big Coils
Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>
Hi Mike,
My coil, the Green Monster: http://dawntreader.net/hvgroup/david/gm.html
has a 12.5" diameter secondary and a whopping 56" major
diameter x 12" minor diameter toroid and normally, I don't
have problems with the sparks striking the secondary. How-
ever, a couple of weeks ago, fellow list members Miles Wal-
dron and Ken May came for a visit from Atlanta and Jack-
sonville, FL, respectively (I'm in Memphis) and of course, they
wanted to see the Green Monster in action. Of course I was happy
to oblidge. However, I had to fire it off in full daylight and the
weather wasn't very good (too windy with rain shorty on the
way). Well, the strong winds actually blew some of the
sparks back into the lower section of the secondary coil and
I ended up with secondary damage that looked much like the
damage to Dr. R's M-200 secondary coil:
http://users.cableaz.com/~chooper/images/tes133.jpg
This also caused other problems that I had not experienced
with the coil up until this time, including racing sparks,
primary turn/turn arcing and the distribution overvoltage
arrester burning out to a dead short. I ended up discarding the
distrbution arrester and I have cleaned off and recoated the
secondary coil with numerous overcoats of poly spar varnish.
Hopefully, this will get it back into working order as I haven't
had a chance to fire it off again yet since then.
I guess the moral to this story is to not fire off your big coil outdoors
in windy conditions, as well as rainy conditions :^O Unfortunately,
my double car garage workshop with its standard 8 ft. ceilings
just can't accomidate a 7 1/2 ft tall, 12 to 15 ft spark spouting
coil, so I'm forced to operate it outdoors and this leaves my coil
firing at the mercy of the weather, which usually ain't too great
this time of year ;^(( Although we don't get lot of snow or extreme
cold (temps seldom fall below +20*F) in this part of the country during
the winter months, if it ain't windy and/or raining, clear and calm evening
temperatures are usually uncomfortably cold for dragging the coil
outdoors. Looking forward to late spring and summer.
David Rieben
----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Wednesday, February 08, 2006 4:06 PM
Subject: Toroid size on Big Coils
Original poster: "MIKE HARDY" <MHARDY@xxxxxxxxxx>
From what I see on the profesional coiling sites, in particular KVA
effects, and Tesla Technology Research, the toroids seem small for
the size of the larger coils. I know the cost of large spun toroids
is prohibatively expensive. In the case of the M-13 magnifier, the
majority of pics, show the discharges comming off the corona ring
and not the toroid. With this coil, and Electrum, many of the arcs
seem to be hitting the secondary. At the Cheesehead teslathon this
past summer, the M-200 of D.C. Cox had several secondary strikes,
one of which severely damaged the sec. He said 'that's what happens
with too small of a toroid. How does one avoid this kind of
catastrophic damage? I'm planning to make a coil similar to DC's
M-150. It uses an 18" form, and I have a 36" spun toroid. I don't
want to destroy my secondary.