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Re: 8 kHz Tesla Coil

Original poster: "Mike" <mike.marcum@xxxxxxxxxxxx>

Maybe putting it in oil will lower the freq. some too and insultate it. The more I think about it, why not just fill the form of a regular coil with powdered iron or whatever they use at 5-10 kHz? The coil form walls would have to be unusually thick (1" acryllic?). Finding a source of a few hundred pounds of the stuff would be tough tho. Guess the ferrite/powdered iron core companies is who I'd check first. Seems like giant wire (12awg+) wouldn't be needed unless you were dumping 50 kw+ into it. Probably need that much for breakout on a huge toroid tho. Maybe a regular-sized toroid with a giant inductance?

Mike
----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Monday, September 19, 2005 2:52 PM
Subject: Re: 8 kHz Tesla Coil


Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Boris,

Multilayer will have breakdown limitations which I know you've already considered. Did you have some thoughts about this as far as a specific winding technique? It will still have the same RF loss issues, regardless.

I think it was Antonio who mentioned a stack of flat coils. This would be interesting to look at. The distance between each flat coil would need to be separated enough to prevent coil to coil breakdown. Winding direction, id to od connection, all would be important to keep the stacks as compressed as possible to take advantage of the proximity (that would be the hard part).

I wound one flat coil a couple years ago. Pretty easy to do. I used a lazy Susan turn table, layed down double sided carpet tape onto a sheet of plexy, and started winding (round and round and round). The tape helped keep the wire in place as the work went on. It would be very interesting to wind several identical flat coils maybe only a 10" o.d. to keep the volts between stacks somewhat low. Flat coils do have a tendency to arc along the surface when over stressed.

Using a 1x10 (id & od) with #24 is 400 turns at near 200 kHz 20" above a ground plane. Putting an identical coil 1" above this coil results in a drop in freq to about 130 kHz. The merit as I see it is simply less wire, but there are breakdown obstacles to overcome not only between stacks but also at the outer and inner edges.

I don't know, just contemplating the possibility. Maybe someone's software out there could look this. But again, the RF losses are independent of coil winding approaches, so no benefit in that respect. And if nothing else, I guess it could be converted to an induction coil with a little work.

It's hard to beat simplicity (single layer helical).

Take care,
Bart



Tesla list wrote:

Original poster: boris petkovic <petkovic7@xxxxxxxxx>

Hi Bart,

-----
<SNIP>
> An 8 awg coil, just for giggles:
>
> 60" x 225" with 1660 turns of #8 and a 60" x 300"
> toroid = 8.07 kHz.
> A lower loss coil of the same freq is just to big
> for most coilers
> and is why our coils are at least x10 the freq or
> more.
>
-----
Try for exercise to calculate dimensions & parameters
of a multilayer helical winding assuming:

-9 layers (sheats) of #8 wire

-coil aspect ratio H/D~3

-equal Ldc inductance of the coil in comparation
 with the inductance of the given classical coil^^


I seem to be ariving at figures much more acceptable
for a low frequency TC garage unit.
At side note ,I wonder if anybody ever tryed
constructing  secondaries in such fashion by a winding
machine,in a purpose for a spark output test
comparation with usual TC designs.

Take care,
Boris