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Re: Toroid size on Big Coils

Original poster: "MIKE HARDY" <MHARDY@xxxxxxxxxx>

I ran my 6" coil a few weeks back in fairly windy weather as well . I
noticed bright flashes on the far side of the coil (the windward side). I
discovered a burned area on the sec. 4 inches up from the bottom. I bet it
was caused by the same thing. This 32" high sec has a 26" spun toroid.
Probably plenty large enough. I too have outgrown my garage with this coil
doing over 6 foot arcs. Flourescent lights are a good target. I also haven't
had good enough weekend weather to try the repaired coil again (I work 2nd
shift). Iwas going to run it sunday night, but declined, as I was afraid RF
interference might interfere with Superbowl reception. Coils are sacred, but
to most of my neighbors FOOTBALL is the holly grail.

----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Thursday, February 09, 2006 10:35 PM
Subject: 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
> 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.
> >
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