It's good to correct "fake news", to help newbies avoid making a coil that will be disappointing at best, or possibly never work. Some of us have been here since the 90s, yourself included, back when we used to get dozens upon dozens of posts every day. Many of us shared our research and results, helping to fine tune our understanding, reinforce good assumptions, and dispel bad ones.
A coil from the 90s that did quite well with numerous primary turns. He proved higher primary turns resulted in lower spark gap losses - I^2R. His site used to have detailed assumptions, builds, and results. He introduced many of us to an easy way to electrically vary the phase of SRSGs, came up with a streamer length formula for a given input, as well and spinning and selling good quality toroids.
TT-42 Tesla Coil Project - jfuturet
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TT-42 Tesla Coil Project - jfuturet
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On Sunday, February 17, 2019, 9:10:19 PM EST, Gary Lau <glau1024@xxxxxxxxx> wrote:
When designing a Tesla coil, one starts with a power source. After we know
how much power is available, this allows us to choose a primary capacitance
that can successfully be charged ~120-240 times per second with the power
available from that power source. The size of the power source also allows
us to choose secondary and topload sizes, and now we have to find a primary
inductance that makes everything resonate at the same frequency. If you
impose the constraint that the primary be just one turn, the primary
capacitance will be far, far, FAR too large to be charged by the power
supply.
Additionally, having a low inductance primary results in correspondingly
higher primary currents, and gap losses are also correspondingly higher.
Colorado Springs Notes is not gospel. Well performing coils with
many-turn primaries are common. I have never seen a single one-turn
primary. If there were an advantage to this, it would be common practice.
The collective experience of modern-day coilers is more instructive than
blindly following Tesla's practices. Kindly cite one well-performing
single turn coil with enough information that we can judge performance
relative to what might be obtained with comparable power using conventional
geometries.
>As Tesla reasoned, high voltage oscillators are Helmholtz resonators.
>Therefore the same physics that make a flute resonate are the same physics
>that make a Tesla coil resonate. The flutist will not become a better
>flutist by having extra pairs of lips, and neither does a Tesla coil become
>a better resonator by having extra primary turns.
A Helmholtz resonator is an acoustic resonance in a cavity, like blowing
over the mouth of a bottle. The practical considerations of Tesla coil
resonance do not REMOTELY translate to acoustic resonance.
The inter-turn parasitic capacitance on primaries is inconsequential, as
the energy in these capacitances it just noise compared to the energy in
the main cap. Yes there are parasitic oscillations, but everything has
more going on if you look closely enough. If primary coils have parasitic
capacitance, secondary coils surely have a great deal more. But as the
relative energies are so small, this simply is not a problem that affects
performance.
Gary Lau
MA, USA
On Sun, Feb 17, 2019 at 8:06 PM David Thomson <aetherwizard@xxxxxxxxx>
wrote:
> On Sun, Feb 17, 2019 at 5:11 PM derstrom8--- via Tesla <tesla@xxxxxxxxxx>
> wrote:
>
> > Hi David,
> >
> > I have never heard of single-turn primary coils used for Tesla coils.
> > You're sure you're not thinking of a multi-LAYER primary? I have seen
> > semi-toroidal dual-layer primary coils to improve coupling and field
> shape,
> > but I have no experience with those myself. I'm strictly referring to the
> > number of turns on a single-layer primary.
> >
> > I'd be interested to see some data on Tesla coils with a one-turn primary
> > coil, if that's actually a thing.
> >
>
> Colorado Springs Notes is my source. By the time Tesla figured out how to
> best tune his coil, he was down to one turn. Of course, the secondary will
> have to be designed around this configuration.
>
> With just one turn of an inductor, you have nearly pure inductance and very
> little capacitance. When you have two or more turns of an inductor, you
> spread out the power transmission path between the primary and secondary.
> As an analogy, the more pairs of lips you add to a flute player, the less
> pressure each pair of lips can blow. You want to minimize the footprint of
> the primary as much as possible so as to get the most power in the smallest
> area to transfer into the secondary. I believe I have seen several guys on
> this list use single turn flat ribbons with success.
>
>
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