RE: Capacitors

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Gary.Lau-at-compaq-dot-com>

I built two different oil-filled poly caps to work with my 15kv NST, only to
have them die.  The first was a single cap with two layers of .04" poly.
The second attempt was two series-connected caps with .04" poly in each.  I
agree with Terry - unless you enjoy the smell of burnt poly, skip the poly
caps and built an MMC cap.

Regards, Gary Lau
Waltham, MA USA

Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>

Hi Tim,

Welcome to the wonderful world of coiling!!

Your transformer is perfect but be sure to use safety gaps across it so it
does not burn out.  Tesla coils and caps can interact to create high
voltages that can destroy an unprotected transformer.  A fancy filter is
nice like the ones below but a simple safety gap is the minimum.

http://hot-streamer-dot-com/TeslaCoils/Misc/NSTFilt.jpg
http://hot-streamer-dot-com/TeslaCoils/MyCoils/BigCoil/protection.jpg
http://hot-streamer-dot-com/TeslaCoils/MyCoils/SmallCoil/small_protection.jpg

I "think" your LDPE sheets need to be like 60 to 90 mils for a 15kV NST!?!
I am not an expert on this but others will chime in here.  I do want to
point out that another brand new kind of primary cap called the MMC is a
far better choice IMHO.  They have obsoleted the oil filled poly caps very
quickly.  Information on this is at:

http://hot-streamer-dot-com/TeslaCoils/MMCInfo/mmcinfo.htm

Feel free to ask more questions because I am sure your have a bunch :-))

Cheers,

	Terry



At 08:04 PM 12/21/2000 -0700, you wrote:
>Hi to All, My name is Tim Walrath. I am endeavoring to build my first
>Tesla Coil. I have purchased a 15000 volt neon sign transformer that
>puts out 450VA at 30MA. I am wanting to build my own capacitors. I am
>planning on using LDPE sheets at 6mil thickness and aluminun roof
>flashing for the conductor plates. I am purchasing some polypropylene to
>make the cases and plexiglass to make the tops. I am having trouble
>figuring out how to figure the capacitance needed for the caps- that is
>how much LDPE to use between each conductor plate. Math never was my
>best subject but I do want to be able to figure this out. Any help would
>be appreciated. Thanks, Tim
>