Re: Dielectric constant table

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

Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>

Hi,

I just wanted to be sure you were aware that nobody makes homemade oil caps 
anymore.  A new cap called the "MMC" has totally replaced them now 
days.  When MMC came on to scene, many people just stopped there oil filled 
cap projects right in the middle and never went back...  See:

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

http://hot-streamer-dot-com/temp/MMCcapSales.gif

http://www.thegeekgroup-dot-org/mmc/

Or, just search on Google for "mmc capacitor"...

Perhaps you really do want to make one of the obsolete types still, but 
just want to be sure you don't go to all that work for no reason.  Since 
the MMC, I think most of the rolled poly cap technology sort of stopped dead.

Polypropylene is the "best" material by far.  Caster oil gives good high 
values and is used in some commercial caps.  The only drawback is the high 
cost.

As for "novel materials", to my memory, there have been zero sucesses...

Cheers,

         Terry



At 04:13 PM 9/18/2003 -0700, you wrote:
>I'm wondering how long it's been since the dielectric tables present on many
>tesla coil sites have been updated.
>
>I'm also wondering about some of the values on them. For example, the table
>says that Mylar is good for 7.5Kv *per mil*. However, one of my early
>attempts at a cap using 10 mils of mylar failed at 5000V rms. Something is
>wrong.
>
>Also, a suggested addition... the giant table at
>http://www.asiinstr-dot-com/dc1.html says that hydrogenated castor oil has a K of
>about 10 at 80* F.
>
>Speaking of which - Anyone ever considered novel materials to build a
>capacitor? For example, Iodine? Iron oxide? Copper oxide?