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Re: [TCML] Form materials, losses, carbon tracking, sealing
Hi Finn, Dr "Hank", all,
Dr. Hankenstein (and Dr. Spark) reside in arid Arizona so one may
tend to think that the arid environment makes for moisture being less
of a prolem with cardboard tube forms in their case. However, I re-
side in SW Tennessee, whose climatic conditions would be a much closer
match to those of Florida than of Arizona. We do get a bit more of
a winter than Floridans but the summers conditions are almost identical
to those of Florida (very hot and very humid). My "first generation"
pole pig powered coil was a 12" x 38.5" coil of #16 AWG wound
on a polyurethaned cardboard concrete former tube (about 660
turns). I left the ink on the tube and stored the coil in an unclimate
controlled garage. When topped with a 9x30 spun aluminum toroid
from a list bulk buy, it produced consistant 8 to 10 ft arcs with no
problems whatsoever. The only reason that it is no longer "in service"
is that I eventually dismantled it in favor of cannibalizing parts to make
an even bigger coil ;^)
Happy sparks,
David
----- Original Message -----
From: "Finn Hammer" <f-h@xxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Saturday, December 15, 2007 12:09 AM
Subject: Re: [TCML] Form materials, losses, carbon tracking, sealing
All,
Perhaps it all comes down to whether you live in apparently very dry
Arizona, presumably very damp Florida or- here in Denmark where these
assumptions were made, and where we have both alternatives interleaved on
an annular basis.
All my coils had plastic sec`s. PVC, mostly. I abandoned polyethylene when
the first one was subject to frost and shrunk so much that the winding
disengaged the thread I`d made for it, and the wire fell down by gravity.
It was unvarnished.
Cheers, Finn Hammer
Dr.Hankenstein skrev:
I'm not so sure if using paper concrete forms is such a bad idea if you
take care to make a careful selection and remove the "inked" layer,
properly dry and varnish the form. For example, here is a picture of a
12" by 48" coil built by Dr. Spark producing about a 8 foot spark. This
coil uses a cement form and has produced arcs in excess or 14 feet with
no problem!
http://www.drspark.org/images/wwt2007/1281.JPG
Spark on!
Woo
dr.hankenstein@xxxxxxxxxxxxx
"We put the fire in the wire."
[Original Message]
From: <FutureT@xxxxxxx>
To: <tesla@xxxxxxxxxx>
Date: 12/14/2007 2:29:09 PM
Subject: Re: [TCML] Form materials, losses, carbon tracking, sealing
In a message dated 12/14/2007 4:21:41 P.M. US Eastern Standard Time,
btmeehan@xxxxxxxxx writes:
Thanks a lot for the info guys, that helps a lot - I heard someone
mention
using concrete forms. If I remember, those were made of very thick
cardboard? Since I have heard several people talk about it - I
imagine that
it is reasonably resistant to lighting on fire when it gets strikes?
I had been looking at a model rocketry site that sells fiberglass
forms, and
even does custom work. Would I be better off with cheaper PVC or
concrete
forms, or would the lower loss tangent of fiberglass be worth
something?
(granted, most of the loss tangent numbers I have seen are in the MHz
or GHz
region, so kHz is probably not a problem with most materials)
(loss tangents)
I would avoid those paper concrete forms. Some of them have strange
lossy materials in them. Some are OK though. Losses in PVC are
not an issue for Tesla coils, but they are subject to carbon tracking
when bad racing sparks or flashovers occur. Probably the most common
material used for secondary forms is PVC. Heating and sealing the PVC
is said to be beneficial but I never bothered with those procedures.
My TT-42, and TT-32 coils both use PVC forms.
_http://hometown.aol.com/futuret/page3.html_
(http://hometown.aol.com/futuret/page3.html) John
**************************************See AOL's top rated recipes
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