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Re: [TCML] largest secondary coil you'd drive with an NST

For a given length of wire your inductance will be greatest with an inductor
that has a large diameter and a short height. However if you make your coil
to short you can get problems with flashover from end to end.

Wire is reasonably cheap compared to capacitors and NST. Using a lot of wire
is the easiest and cheapest way to increase spark length. I  would recommend
using 22 gauge on a 12 inch by 4 ft concrete form.This will give a nice low
frequency and if (when) you upgrade to using more NST (or a pole pig) you
will be all set. Finer wire also works and I would not be surprised if one
could drop down to as fine as 28 gauge for a pole pig powered coil. But fine
wire does not seem to survive strikes very well so we use the thicker stuff
as insurance.  (tiny wires are hard to wind, they get crossovers easily)
Jared Dwarshuis
On Dec 14, 2007 12:47 AM, Tim Meehan <btmeehan@xxxxxxxxx> wrote:

> I hate to ask this too - but what is the optimum aspect ratio for a
> secondary?  I've run JAVATC, and have built a feeble (but pretty) classic
> tesla before ... and have read but probably poorly understood a few
> papers.
> I think that I'm ready to build version two of the static-gap,
> NST-powered,
> properly filtered and protected coil.  I just want to make sure that I
> learn
> as much as possible before I start purchasing things that probably won't
> suit my needs.
>
> On Dec 13, 2007 5:56 AM, David Rieben <drieben@xxxxxxxxxxx> wrote:
>
> > Hi Tim,
> >
> > It's a bit of both ;^) As the power levels increase, this calls
> > for larger circuit components (primary C and L and conse-
> > quently larger secondary C and L). Of course there is some
> > flexibility to these parameters and you can increase the output
> > of any given coil by applying more power, within reason.
> > However, a larger diametered secondary coil has a greater
> > inductance than a smaller one and will therefore yield longer
> > sparks. For example, a 12" diameter secondary coil will
> > yield longer ouput sparks than an 8" diamter secondary coil
> > from a 10 kVA power source, assuming all other aspects
> > of the coil are identical. Of course both coils will produce
> > longer sparks from a 10 kVA power source than from
> > a 5 kVA power source. If you are sticking with NST
> > power, then 6"  should be as large as you should need
> > to go for secondary coil diameter. If your going with pig
> > power, then you should opt for at least a 10" diameter
> > secondary coil, if not 12" or more to properly utilize the
> > available power. As far as height goes, optimum aspect
> > ratios (height vs diameter) are generally between 3:1 and
> > 5:1 with the larger coils generally falling toward the lower
> > range and the smaller ones to the higher range. You should
> > choose a wire size that will allow you to wind 1000 to 1200
> > turns while maintaining the secondary's dimensions within
> > the optimum aspect ratio.
> >
> > Hope this helps,
> > David
> >
> > ----- Original Message -----
> > From: "Tim Meehan" <btmeehan@xxxxxxxxx>
> > To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> > Sent: Wednesday, December 12, 2007 8:20 PM
> > Subject: [TCML] largest secondary coil you'd drive with an NST
> >
> >
> > > Is there some given maximum size of secondary coil (diameter or
> height)
> > > that
> > > you would consider driving with an NST?  For instance, I hear a lot of
> > > people building 4-inch diameter secondary coils of various heights,
> > > prehaps
> > > even 6-inch diameter or so ... but is there some correlation of
> > > transformer
> > > KVA rating and secondary coil size, or is it really more about how
> much
> > > bang
> > > you can get out of a primary capacitor?
> > > _______________________________________________
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> > >
> >
> >
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> >
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