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Re: secondary question

Original poster: "Drake Schutt" <drake89@xxxxxxxxx>

Thank you all for the responses, and I also have another question. What is the deal with end caps. I know people put like pieces of plastic inside their coil-forms to seal them or something. What purpose does it serve and is it beneficial or necessary.


On 8/8/06, Tesla list <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx> wrote:
Original poster: "Barton B. Anderson" <<mailto:bartb@xxxxxxxxxxxxxxxx>bartb@xxxxxxxxxxxxxxxx>

Hi Drake,

Teslamap has been around a few years. It's probably ok, although I
don't use it. Most of the programs are a good ballpark, so not to
worry there. What is important is that you either allow a couple
extra turns for tuning (primary) or you tune the coil with scrap wire
and then build a nice primary replica of the scrap wire.

Cellcore is just a term regarding the construction of the plastic
(cellular bonding). The technique is used with all types of plastics.
The advantage is strength under pressure. Cellcore PVC would be for
burying underground in a location that might see large loads where
the earth would be compressed around the form (thus, the form is
designed to not crack under a given pressure limit). It should be
fine for coiling. Some of us probably use cellcore and don't realize
it. I believe I have my 8.5" diameter coil wound on cellcore (1/4"
thick walls) - no problems. Definitely clean it before winding and
sealing doesn't hurt either (helps prevent hygroscopic absorption).
The cellcore won't enhance your coiling. There may be a little more
dielectric loss in the form (the thicker, the larger the loss, but
the losses are likely insignificant).

For a 12/30 transformer, about 0.75" is appropriate for pri to sec
proximity. I wouldn't go over 1" as this will just reduce coupling
and you may end up with the secondary below the primary
(unnecessarily). I just built a little 7.5/20 NST coil and I'm
running 0.5" clearance without any problem (0.5" is the beginning of turn 1).

Take care,

Tesla list wrote:

>Original poster: "Drake Schutt" < <mailto:drake89@xxxxxxxxx>drake89@xxxxxxxxx>
>hey all,
>I've now assembled most of the materials I need to build my first
>tesla coil.  I used teslamap57 to design it, and ive never heard of
>anyone on-list using this.  Is it accurate and reliable?  I am going
>to wind about 1000 turns of 26awg wire on 3.5 OD pvc pipe.  the only
>problem is that it is pretty thick-walled and its called like
>cellcore or something like that, basically insulated i guess.  Will
>this cause problems?  Also, will it enhance the performace of my
>soon-to-be coil if i clean, sand, and coat my secondary form before
>i start winding it?  Also, if my secondary has an OD of 3.5in, then
>what should the diameter of the hole in the primary be?
>any help appreciated as always
>-dr. drake
>seconday(hopefully) 17inx3.5in=999 turns of 26awg