Re: help needed with building a mini table top tesla coil

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

Original poster: "Jim Mitchell" <electrontube-at-sbcglobal-dot-net> 

Holy ***, .00795pF?  thats nothing!  You must MUST MUST be mistaken.  Thats
like the capacitance of the tip of a screwdriver.

Regards - Jim Mitchell
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, February 11, 2004 2:15 PM
Subject: Re: help needed with building a mini table top tesla coil


 > Original poster: mizpoon <mizpoon-at-burningart-dot-com>
 >
 > Hi everything,
 >
 > firstly, thanks for your advice on my tesla coil project.
 >
 > i'm now looking for the right capcitor for my tesla coil and am running
 > into difficulties.
 >
 > the capacitor I think I need is about 0.00795 pFarads and is rated at
 > 10KV.
 >
 > However, when calling up a few places, this kind of capacitor is hard to
 > find... do you guys have any idea where I could find such a thing?
 >
 > everyone I talk to says that the capacitor is tiny, and that I'm trying to
 > get the wrong thing... what do you think is the problem here?
 >
 > I know that Ebay has many capacitors for sale, but there are pretty jumbo
 > caps for a larger tesla coil...
 >
 >
 >
 > On Wed, 4 Feb 2004, Tesla list wrote:
 >
 >  > Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz>
 >  >
 >  > On 4 Feb 2004, at 11:49, Tesla list wrote:
 >  >
 >  >  > Original poster: mizpoon <mizpoon-at-burningart-dot-com>
 >  >  >
 >  >  > Hello everyone,
 >  >  >
 >  >  > I was hoping you could help me with my first table top
 >  >  > tesla coil. This is really my first high voltage
 >  >  > experiment, so any input you have would be very
 >  >  > helpful.
 >  >  >
 >  >  > I have a mini secondary coil and toroid, and am trying
 >  >  > to figure out its resonant frequency so that I can
 >  >  > size up the transformer and capacitor I need for the
 >  >  > primary.
 >  >  >
 >  >  > my secondary coil has a radius of 0.5 inches, 7inches
 >  >  > high, and has 448 turns of very fine wire.
 >  >  >
 >  >  > the toroid is a brass doorknob (!), about 2.125 inches
 >  >  > wide, 1.5 inches tall.
 >  >  >
 >  >  > According to my calculations, I have an inductance of
 >  >  > 673 mhenries, and a capacitance of ~ 7 micro farads
 >  >  > (for both the coil and the toroid), leading to
 >  >
 >  > I do believe the units should be microHenries and picoFarads. On the
 >  > face of it, the values look OK.
 >  >
 >  > Malcolm
 >  >
 >  >  > -- a frequency of 3887883 hertz --
 >  >  >
 >  >  > -- a transformer of 10K at 30ma, and a capacitor at   0.00795
mfarads
 >  >  > --
 >  >  >
 >  >  >
 >  >  > before I go ahead with these calculations, can you
 >  >  > tell me if this seems even vaguely right, or am I way
 >  >  > off with these calculations?
 >  >  >
 >  >  > I used this site for most of my calculations btw:-
 >  >  > http://home.earthlink-dot-net/~electronxlc/formulas.html
 >  >  >
 >  >  > Thanks again for all your help,
 >  >  >
 >  >  > mizpoon
 >  >  >
 >  >  >
 >  >  >
 >  >
 >  >
 >  >
 >
 >