Re: Capacitor needed

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "miles waldron" <mileswaldron@xxxxxxxxxxx>

I bought a "great" 0.1 UF 15KV capacitor from e-bay for $15 and it totally
melted into stinky slag. I had to laugh about it. Use them CDEs.

Miles

----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Wednesday, December 06, 2006 5:57 PM
Subject: Re: Capacitor needed


> Original poster: "Jack" <Jack@xxxxxxxxxxxxxxx>
>
> Hi Gary and all,
>
> The Russian cap is listed as
>
>
>
> Soviet capacitors PKGT-I 15KV
>
>
>
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ih=007&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=170055836253&rd=1&rd=1
>
> and my friend Frank Jones ( you may know him ) located them for me.
>
> Not much description on this eBay listing but Frank feels they will
> work for the Model T-Tesla coil when substituting the 3/30 NST for the
T-coil.
>
> I would be interested in your thoughts.
>
> Again, thanks for the helpful notes on capacitance. I am learning,
> albeit slowly!
>
> Best,
>
> Jack
> Hilo
> ----- Original Message -----
> From: Tesla list
> To: tesla@xxxxxxxxxx
> Sent: Wednesday, December 06, 2006 8:58 AM
> Subject: RE: Capacitor needed
>
> Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>
>
> Hi Jack,
>
> Beware that there is much more to choosing a capacitor than voltage and
> uf ratings.  The dielectric material is critical in Tesla coil
> capacitors.  Polypropylene (PP) is the state of the art and first choice
> for TC caps.  Mica was widely used, but as I had mentioned, is bulky and
> expensive when compared to PP.  Mylar, a.k.a. polyester, is NOT suitable
> for TC caps, as it is lossy at RF frequencies and will get hot and the
> cap will die.  There are many types of ceramic dielectrics, and almost
> all of them are also not suitable for TC caps.  The losses are high and
> the capacitance changes significantly with temperature.
>
> Even among polypropylene caps, there are good caps and there are bad
> caps, the difference being the interconnect between the foil plates and
> the leads.  The high pulse currents we use require a very robust
> construction!  It's very difficult and no doubt frustrating to beginners
> to get this, ignoring what appear to be dream-deals on eBay for much
> more expensive parts that a bunch of strangers on the list suggest.
>
> If it's not already too late, you may want to float your Russian jobs
> past the List to see what we think.  While it's remotely possible that
> they're suitable, I think it's more likely that they are small, Mylar
> units that will die in a coil without so much as a whimper.
>
> Regards, Gary Lau
> MA, USA
>
>
>
>   > Original poster: "Jack" <Jack@xxxxxxxxxxxxxxx>
>   >
>   > Thanks for your offer, but today we found a couple of Russian jobs at
>   > 15kv and .01 uF that will work perfectly.
>   > You and Gary are kind to respond!
>   > JT
>
> Have a great day!
>
>
>