Re: [TCML] Acrylic Covers

[Phillip Slawinski <pslawinski@xxxxxxxxx>]

On Thu, Apr 22, 2010 at 08:40, Brandon Garretson <garretsontech@xxxxxxxxx>wrote:

> I am nearing the completion of the second incarnation of my 4” Tesla Coil.
> After a good deal of time spent polishing and cleaning the copper
> primary I got the idea of installing an acrylic disk over it in order
> to help protect it from dust, fingerprints, falling objects, idiots,
> etc…
>

That's a good idea.  I incorporate this on all my flat primaries now.  It
helps smooth the e-field around the primary to a limited degree, as well as
providing protection to the finish of the copper.


> In searching the archives, I read about this being done before but
> found nothing regarding its effect on the device.
> I also found an acrylic tube that slides perfectly over the secondary
> coil leaving an eighth of an inch clearance between the windings and
> the ID of the tube.
>

If there is ANY air between the tube and the secondary windings the tube's
only function will be aesthetic.  If you would like it to provide electrical
protection to the secondary you will need to fill the space between the tube
and the windings with oil or epoxy.  If you don't already have the tube I'd
suggest looking into using epoxy, it would probably be cheaper, and when
applied properly provides a glass-like finish that is very resistant to
racing sparks and flash over.


> Aesthetically it is all very pleasing, but will that much plastic have
> a measurable impact on the performance of the coil?
>

If you take the steps mentioned above you would be able to push the coil
harder without having to worry about flash overs or racing sparks.


> It looks as though it may help prevent racing arcs due to the lack of
> any direct path of air between the primary and secondary but I cannot
> figure out in what way (if any) it might adversely affect the
> relationship between L1 and L2.
>

There should be no effect.  You can adjust for any coupling changes you
might have due to the inner diameter of the primary accommodating the
secondary form.


> The acrylic over the primary would be .25” and the wall thickness of
> the tube over the secondary .125” for a total of .375" (3/8").
> Has anyone experimented with this before or is it common knowledge
> that this is just too much dielectric?
>

Too much?  Hardly.


>
> Thanks!
>
> Brandon from Jersey
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