RE: Large Tesla Coil Construction Details - Help Improving The Primary

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>

Using a 15/60 midpoint-grounded NST, a 1" clearance between the inner
primary turn and the 1st secondary turn has proven to be adequate,
provided there are no sharp edges.  But if you're using a pig, you have
the option to ground the inner primary turn, in which case you need zero
clearance.  Even so, I'd still stick with the inch.

The coupling value may be accurately calculated using MandK, available
on Terry's site at
http://hot-streamer.com/TeslaCoils/Programs/Programs.htm.  But the
maximum coupling one may use before racing sparks occur is still just
determined experimentally, usually using "primary plane at 1st secondary
turn" as a starting point.

Regards, Gary


> Original poster: "Cameron B. Prince" <cplists@xxxxxxxxxx>
>
> Hey guys,
>
> With all the comments regarding the extra resistance of bronze and
corona
> breakdown of wood, I think I will rebuild the primary plate using HDPE
with
> pure copper.
>
> I have questions regarding coupling and the alignment of the primary
in
> relation to the secondary. I basically followed Terry's design with
the
> 4.25" distance between the primary and secondary. This is even though
he's
> using 30KV and I'm using 14.4KV. I did leave room to tighten up the
coupling
> somewhat if need be. How can I calculate this with more certainty?
>
> Also, I aligned the first winding of both the primary and the
secondary to
> the same height. Most designs I've looked at don't specify whether
there is
> a difference and a lot have insulation so thick in between you can't
really
> see to even guess. What is the rule of thumb here?
>
> Thanks,
> Cameron
>
>
>  > -----Original Message-----
>  > From: Tesla list [mailto:tesla@xxxxxxxxxx]
>  > Sent: Wednesday, July 27, 2005 8:41 PM
>  > To: tesla@xxxxxxxxxx
>  > Subject: Re: Large Tesla Coil Construction Details - Comments
>  > Requested
>  >
>  > Original poster: "Peter Terren" <pterren@xxxxxxxxxxxx>
>  >
>  > No but it may penetrate the varnish by melting or cracking.
>  > When HV is in contact with wood there is corona which
>  > gradually carbonises a very small point next to the most
>  > intense corona. This becomes conductive and the process
>  > spreads like a cancer. It may only take a weak spot or bit of
>  > moisture to start.  I have this problem on my display lifter
>  > that has been running for months.
>  > To see a demonstration of wood burning from HV look at this:
>  > http://tesladownunder.com/misc1.htm#Wood%20burn%20fractals
>  >
>  > Peter (Tesla Downunder)
>  >
>  >
>  > >Original poster: "Cameron B. Prince" <cplists@xxxxxxxxxx>
>  > >
>  > >Hi Peter,
>  > >So you think the heat could possibly reach the wood's flash point?
>  > >Thanks for the input,
>  > >Cameron
>  > >
>  > > > > Original poster: "Peter Terren" <pterren@xxxxxxxxxxxx>
>  > > > I worry a little about using wood as a base for a
>  > multikilowatt hot
>  > > > primary with 20kV across the used winding.
>  > > > Still, looks like you can easily replace it.
>  >
>  >
>  >
>