Re: Dielectric constant table

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

Original poster: "Nick Andrews" <nicothefabulous-at-hotmail-dot-com> 

Has anyone tried polypropylene comic book bags in cap construction?  The 
really cheap ones are polyethylene, but the good ones are polypropylene.
Some are mylar, but they are more, and I imagine won't work at HF.

Nick A


>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Re: Dielectric constant table
>Date: Thu, 18 Sep 2003 17:33:55 -0600
>
>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?