RE: [TCML] party cup capacitors

[Brian Hall <brianh4242@xxxxxxxxxxx>]

Would stackable cups/plates of a good dielectric strength work better?  Such as thicker plastic, or those styrofoam coffee cups, or even glass cups?  I remember someone posted a while back about a coil made decades ago, where the cap was tin foil glued to either side of a window pane .. and it worked.   Though I have burned through glass with a raw 15/30 NST at full power ... 

... hmmm i just noticed the famed 942C20P15K cap for $5 each (and price breaks as you get more)  here 
http://www.onlinecomponents.com/buy/CORNELL-DUBILIER/942C20P15K-F/
 
I did some googling and did not see $3 price range caps like that .. whereabouts is a good online store with a better price for a cap that's around that good, that would hold up to the merciless trials a coil puts its caps through?

---------------------------------- 
Brian Hall 




 
> Date: Tue, 2 Nov 2010 17:29:41 -0400
> From: phalenor@xxxxxxxxx
> To: tesla@xxxxxxxxxx
> Subject: Re: [TCML] party cup capacitors
> 
> On 2010-11-02 at 08:25, Brandon Garretson ( garretsontech@xxxxxxxxx ) said:
> > This idea has been around for a decade and this is the first Im hearing of it?
> >
> > http://www.angelfire.com/ak5/energy21/cupcap.htm
> >
> > I must have gone through about 90% of the archives on this forum over
> > the past two years and I have never had the urge to try to build a
> > homemade cap until now.
> >
> > Has anyone proven that these arent worth the effort?
> 
> They aren't worth the effort. Been there, done that, spilled lots of oil 
> ;)
> 
> I think for a party cup capacitor housed in a 4"x12" piece of PVC pipe, 
> filled with vegetable oil, with about 20 'plates', it weighed maybe 10lbs, 
> gave maybe 1-2nf of capacitance, and could barely hold up to a 12kV NST.
> 
> Until you build enough of these to put in series-parallel to get the 
> desired voltage and capacitance, you'll have some massive oily mess.
> 
> And the second one of the caps punctures, you get to tear the whole thing 
> apart.
> 
> When I made mine, I used aluminum foil tape, and the cheapest red party 
> cups I could find. I suppose if you were using low enough voltages, this 
> type of cap might be acceptable if you're really on a budget. Might even 
> get away without the oil, though the corona will eventually break down the 
> plastic. Might also experiment with plastic party plates as well and make 
> a 'plate cap', though the one I made lasted all of 5 seconds...
> 
> Just for documentation purposes, here's a picture of the first cup cap I 
> made, using a clear plastic container. Lasted one night of experimenting 
> with a 12kV 30mA NST, http://kb3ewy.com:8000/old/images/cupcap.jpg
> 
> Save yourself the time and money and buy some MMC type capacitors. I think 
> they're still about $3 a cap these days...
> 
> --andy
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