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Re: tesla coil



Original poster: "Steve Cook by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Steve-at-g8cyerichmond.freeserve.co.uk>

Certainly styrofoam donuts worked when covered in foil, in fact I have used
this method on 4 or 5 small coils. I now use self-adhesive aluminium tape.

----- Original Message -----
From: Tesla list <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, January 06, 2001 5:20 AM
Subject: Re: tesla coil


> Original poster: "Joshua Lovato by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <jlovato-at-newmexico-dot-com>
>
> Hey thanks for the help, I got my little coil putting out arcs over 5
inches
> long! (better then the 3 inches it was doing before :-)) I found that one
of
> the things that seemed to make the most difference was the terminal
> (toroid). I tested it by placing a large tin can like those used to hold
> Christmas cookies on top of the coil. This made a big improvement in
> performance. Does anyone have any ideas on how to make a small toroid that
> has a relatively smooth surface? I was thinking of constructing a toroid
out
> of an 8" doughnut shaped Styrofoam ring and wrapping it with aluminum
foil.
> Would this work? Also I would probably have to figure out the capacitance
> that the toroid would have right?
>
> Also another thing that I would like to ask is about grounding. Right now
I
> don't have my small 8 inch coil grounded to anything (I use a wire near
the
> discharge terminal that is attached to the bottom connection of the
> secondary to draw arcs) I know this is probably not the best (or safest)
way
> to do things. However I an afraid to use the household ground for the coil
> (don't want to blow up the computer or entertainment center). I do have a
RF
> choke on both output terminals of my neon transformer with safety gaps.
> Would this provide enough protection? Would MOV's on the 110 volt
connection
> from the transformer help? Or should I use a separate grounding system (a
4
> foot rod in the ground)?
>
> Thanks,
> Josh
>
> P.S. I will have more pictures soon on my website at:
> www15.brinkster-dot-com/thebytefiles/
>
>
>
>
>
> ----- Original Message -----
> From: Tesla list <tesla-at-pupman-dot-com>
> To: <tesla-at-pupman-dot-com>
> Sent: Tuesday, January 02, 2001 9:32 PM
> Subject: Re: tesla coil
>
>
> > Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>
> >
> > Hi Josh,
> >
> > Neat!  Let's see what we have.
> >
> >
> > At 07:40 PM 1/2/2001 -0700, you wrote:
> > >Transformer voltage: Some where between 9-10kv. The transformer was
given
> to
> > >me by a friend of mine at the local radio station and has no name plate
> or
> > >any type of label on it :-(.
> >
> > Is this a NST type or current limited type transformer?  I will assume
it
> is.
> >
> > >
> > >Transformer current: 20-30mA, is there a way for me to measure the
> current
> > >of the transformer? possibly by setting a meter to read current and
> > >connecting it across the transformer before plugging it in?
> >
> > You can measure the current with a meter but if anything is set wrong or
> > anything is not just right, it will fry the meter.  Best just to assume
> the
> > voltages and currents are ok for now.
> >
> > >
> > >Primary coil inner diameter: 5 inches
> > >
> > >Primary coil turns: 3 made of 12 AGW wire.
> > >
> > >Primary coil distance between turns: .25 inches
> > >
> > >Primary cap size : 12nF
> > >
> > >type of spark gap: Multi point spark gap made with 8 1/2" copper tubes
> > >bolted to the inside of a 3 inch PVC pipe
> > >
> > >Secondary coil diameter: 1.75 inches
> > >
> > >Secondary coil turns: 680
> > >
> > >Secondary coil length: 8 inches
> > >
> > >Height of first turn of secondary coil above primary coil: 1/4" from
the
> > >bottom of the primary (im using a Helical primary). I found that if i
> lowerd
> > >the secondary coil further into the primary the output increased
> dramaticaly
> > >( from 1 inch sparks to 3 inches).
> > >
> > >Terminal diameter (side to side): You guys are going to laugh but I am
> using
> > >a 1.5 inch Styrofoam ball wrapped with aluminum foil.
> > >Height of terminal (center) above primary coil: 10.75"
> > >
> > >I will be posting some pictures of the coil on my website as soon as I
> get
> > >it updated :-)
> > >
> > >Thanks for the help,
> > >Josh
> > >
> > snip...
> >
> > Here are the numbers I get using a bunch of programs and formulas:
> >
> > Your secondary coil's inductance is 4.03mH
> > The total secondary system capacitance is 4.56pF
> > Your secondary system frequency is 1.17MHz
> >
> > For the primary to be tuned at 1.17 MHz you would need to tap the
primary
> > coil at 2.38 turns with a 12nF cap.  That gives a primary inductance of
> > 1.53uH and a primary system frequency of 1.17MHz like the secondary.
> >
> > The primary to secondary coupling is around 0.08
> >
> > So, I would try moving the primary tap point in to around 2.4 turns but
> try
> > a bunch of places around there to see where you get the best spark.
> >
> > If that does not seem to help much I would try drawing an arc from each
> leg
> > of the transformer to ground to be sure it is working properly.
However,
> I
> > am assuming you have a current limited NST and can do such a test
safely.
> > If not, we can help you out there.
> >
> > The cap may be the next suspect.  If it gets hot or does anything odd,
> that
> > would be a bad sign.
> >
> > Pictures would be great and help too.  If you send them as attachments
to
> > (now with virus scanning ;-)):
> > terry-at-hot-streamer-dot-com
> >
> > They will show up at:
> > http://hot-streamer-dot-com/temp/
> >
> > So that is the first shot at figuring it out.  See how it goes...
> >
> > many of the numbers above are from formulas like those at:
> > http://home.earthlink-dot-net/~electronxlc/
> >
> > Cheers,
> >
> > Terry
> >
> >
> >
> >
>
>
>
>