In various comparisons I made using high quality primary conductors such as copper tubing versus lossy conductors such as braided coax cable. I was not able to detect any difference in output spark lengths from the tesla coil. From a practical standpoint, the losses due to the poor quality conductors were completely over-shadowed by the spark gap losses. This was all part of work I did in the past to find out what really makes a difference and what doesn't, spark-length-wise. The spark length was around 42 inches in these tests.
John
-----Original Message-----
From: Tedd Dillard <tedd.dillard@xxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Tue, May 5, 2020 1:15 pm
Subject: Re: [TCML] Primary design question for minimum radius
Gary I thank you for your very helpful and interesting experiment,
I really appreciate the detailed description of the set up and the
objective analysis.
What do you think about using insulation between the turns of the primary
and winding it with only the thickness of the insulation between the the
turns..
Also you mention that the primary losses may be over shadowed by other
losses like the spark gap. But any loss eliminated is performance gained
especially if it is easily eliminated.
Do you think that the test results would have been significantly different
it there had been a secondary present.
You kept the inductance very close in all variations but would a secondary
present along with coupling variations likely been significant?
Thanks again for your great work.
Teddy
On Mon, May 4, 2020 at 5:42 PM Gary Lau <glau1024@xxxxxxxxx> wrote:
> I believe I recall that with ribbon conductors, the current flow is
> concentrated at the top and bottom edges and the copper in the middle is
> mostly wasted. Some time ago I performed an experiment to compare primary
> losses for various primary coil geometries, including ribbon, tubing, Litz,
> and various other things. The copper ribbon was unrerkable in terms of
> losses. See http://www.laushaus.com/tesla/primary_resistance.htm
>
> That aside, I can't imagine how to keep 3 spirals of tubing aligned with
> each other and tapping it.
>
> Regards, Gary Lau
> MA, USA
>
> On Mon, May 4, 2020 at 5:25 PM Terry Oxandale <toxandale@xxxxxxxxxxxxx>
> wrote:
>
> >
> > I'm rebuiding my primary (and other parts), with the intent of using a
> > larger diameter tube (going from 1/4" to 3/8"). It would be very
> convenient
> > to use the same primary footprint I'm currently using, and feel I could
> do
> > this with the larger tubing, but would like to have some margin of unused
> > turns for flexibility in components.
> > So my question to the group relates to primary turn stacking. I'm
> > considering stacking 2 to 3 layers of 1/4" tubing (to resemble a ribbon
> > versus a single, larger diameter, round conductor) into each slot of the
> > structure. Looking at increase power, efficiency, etc, and think this may
> > be a way to keep the radius constrained, while improving the performance.
> > Thoughts and experiences of this from the group?
> > Terry
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