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Re: Terry filter alternates?

Original poster: "Black Moon" <black_moons@xxxxxxxxxxx>



From: "Tesla list" <tesla@xxxxxxxxxx>
To: tesla@xxxxxxxxxx
Subject: Re: Terry filter alternates?
Date: Thu, 02 Dec 2004 18:20:09 -0700

Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi,

At 02:47 PM 12/2/2004, you wrote:
Hi, Im intrested in building a filter for my NST, but can't quite get all the money for the parts...

It is sort of obnoxiously expensive... Had to use common off-the-shelf parts so anyone could do it...


Im only using a 15kv 30ma NST, so I was wondering if mabey I could: Remove the movs, use two 10kv to ground caps across the NST, leave safty gap across the NST, Replace the 100watt resistors with 10watt 1kohm (or mabey 2 10watt 1kohm in series per side? 2kohm won't be a big deal at 30ma)

The resistors get pretty hot as is. Smaller ones would probably fry. I would just use safety gaps, but make them well and set them carefully,
that will get you 90% there.

Well thats why I was thinking of adding inductors to reduce the load on the resistors.
PS: about what size filter cap should I use for a 15kv 30ma nst?

And possabley an aircore inductor in series with the resistors, Probley something looking like a pencil with 2 or 3 layers with some insulator beween em, or mabey all wound back and forth in little sections so each winding is only next to a winding withing x kv, Any suggestions on value to shoot for if I do? Operateing freqency is about 400khz for the coil

Forget the inductors, they are useless. Put you effort into a good safety gap and be happy ;-)

I still think smaller higher value resistors would probley be fine, since its the ringdown that causes the disipation higher value resistors would disipate less, 30ma at 4kohm is still only 3.6 watt, and at lower chargeing current there would be less ringdown events. Any thoughts?


Cheers,

        Terry