question about a mica capacitor

[Jason Banco]

I'm wondering whether or not this can be used as part of a planned 250 KV
Tesla coil:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=ADME:B:EOIBSAA:US:11&Item=260331142646

It would be part of the primary with a 5 KV OBIT.

Thanks,
Jason

[Bert Hickman]

Hi Jason,

It may work as long as you don't try to use a higher voltage NST or
OBIT, and you use a carefully adjusted safety gap to prevent
accidentally overvolting the cap. Normally the tank cap DC voltage
rating should be at least 3X the AC RMS rating of the HV transformer you
are using. You may also need to carefully monitor the temperature of the
capacitor during operation to make sure it doesn't get too hot from the
high tank circuit current.

You may want to consider using a group of foil-film polypropylene
snubber capacitors (called a Multi Mini Cap, or MMC) instead. These are
self-healing, low loss, and lower cost alternative to more expensive
pulse caps or mica caps. They have been found to offer maximum
performance and minimal cost for thousands of Tesla coil enthusiasts
worldwide. See the following sites for more information or Google "MMC
capacitor":

http://deepfriedneon.com/tesla_f_mmc.html
http://www.tb3.com/tesla/capacitors/capacitors.html

Bert
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[Jason Banco]

"Bert Hickman" <bert-h...@comcast.net> wrote in message
news:Scadnapf-_5KVwXU...@giganews.com...

> Jason Banco wrote:
>> I'm wondering whether or not this can be used as part of a planned 250 KV
>> Tesla coil:
>>
>> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=ADME:B:EOIBSAA:US:11&Item=260331142646
>>
>> It would be part of the primary with a 5 KV OBIT.
>>
>> Thanks,
>> Jason
>
> Hi Jason,
>
> It may work as long as you don't try to use a higher voltage NST or OBIT,
> and you use a carefully adjusted safety gap to prevent accidentally
> overvolting the cap. Normally the tank cap DC voltage rating should be at
> least 3X the AC RMS rating of the HV transformer you are using. You may
> also need to carefully monitor the temperature of the capacitor during
> operation to make sure it doesn't get too hot from the high tank circuit
> current.
>
> You may want to consider using a group of foil-film polypropylene snubber
> capacitors (called a Multi Mini Cap, or MMC) instead. These are
> self-healing, low loss, and lower cost alternative to more expensive pulse
> caps or mica caps. They have been found to offer maximum performance and
> minimal cost for thousands of Tesla coil enthusiasts worldwide. See the
> following sites for more information or Google "MMC capacitor":
>
> http://deepfriedneon.com/tesla_f_mmc.html
> http://www.tb3.com/tesla/capacitors/capacitors.html
>
> Bert

Hi Bert,

Thanks for the info. Unfortunately, I'm having a hard time tracking down
these capacitors. One of the link lead to "The Geek Group", but it doesn't
seem to have them available anymore. And I can't seem to find them at the
other. Do you have any order sources at a good price?

Thanks,
Jason

[Bert Hickman]

Hi Jason,

You can find 0.15 uF 2 kV polypropylene caps (CDE 942C20P15K-F) on eBay
- see auction numbers 200304228772 and 200312005660 for example.

"The Geek Group" no longer supplies them. However, professional Tesla
coiler DC Cox (at Resonance Research Corporation) also carries these -
you can contact him at reso...@wildblue.net

You can also go to Cornell Dubilier's website (http://www.cde.com) and
click the "Services" tab at the top of the page, and then "Stock Check"
to display a list of distributors. Use the 942C20P15K-F film capacitor
as the part number. You can then call the individual distributors to
find pricing, minimum order requirements, quantity discounts, shipping
costs, etc. Many coilers have found that Richardson Electronics offers
the best overall pricing. Their inventory is constantly changing, so
it's likely that they have either them in stock or will have them in
stock shortly.