Re: Capacitor search

To: tesla-at-pupman-dot-com
Subject: Re: Capacitor search
From: Dan Gowin <gowin-at-epic-1.nwscc.sea06.navy.mil>
Date: Thu, 05 Dec 1996 09:37:42 -0500

Tesla List wrote:
> 
> >From Esondrmn-at-aol-dot-com Thu Dec  5 00:20:41 1996
> Date: Wed, 4 Dec 1996 13:40:50 -0500
> From: Esondrmn-at-aol-dot-com
> To: tesla-at-pupman-dot-com
> Subject: Capacitor search
> 
> Well, it's about 15 degrees here and supposed to snow 6" to 8" tonight.  I
> have been reading about people building small coils and like the idea of
> making a table top model out of a wine bottle.  Sounds like a good winter
> project.  I've done some calculations and concluded that a wine bottle 3.0"
> in dia. wound 7.0" high with #28 wire and a small 5" or 6" toroid would
> oscillate at about 654 mhz.  With a 12 turn primary made out of #10 bare
> copper wire I would need about .0045 microfarads to tune at 80% of the
> primary.
> 
> My question here is does anyone have some .002 mf capacitors they would be
> willing to part with?  I plan to use a 9 or 12 kv  30ma transformer.  I have
> never used the doorknob type capacitors and know they are not the best but
> they would probably work in this application.  I would probably want a 15 or
> 20 kv ac rating.
> 
> Also, I need to find a source of large (2" or 3") ferrites so I can wind some
> safety chokes to protect the transformer.  Anyone know of a source?
> 
> Thanks,  Ed Sonderman

Ed, I did some off the cuff calcs on your numbers.

	Unloaded Resonate Frequency	908 khz
	Unloaded Q			93.67
	Loaded Q should be		41.63
	Inductance			7.034 millihenry

	Isn't your inductance a bit to low for this size
of coil?

D. Gowin