RE: design for new capacitor

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Mark Dunn" <mdunn@xxxxxxxxxxxx>


Adriano:

I tried the same thing with 8" X 12" X.032" thick FR-4 sheets double
sided with copper. I stripped off the outer 1/2" of copper along all 4
edges and both sides to keep prevent cross-over.  As you noted, each
sheet is a capacitor and I alternated the voltage on each board so that
"like" voltage copper surfaces would face each other.

Submerged in oil (5) sheets gave me 13.84 nF.  Unit worked well for a
Tesla Coil.  In air, the arc ran across the surface of the FR-4 around
the edge and back across the other surface.

My final copper area was 7" X 11" less an area to pass brass bolts
through to connect the thing together.  This bolting gets difficult to
explain.  I can send you a drawing of both sides of the cap if you are
interested.
Note: Most "List" subscribers hate Parallel Plate Caps!

Mark


>Original poster: "Dr. Adriano Mollica" <adriano.mollica@xxxxxxxxxxx>

>Hello list,

>i just bought on ebay a certain quantity of douple faces copper fiber
glass plate for very >cheap.

>i will like to use them to make a capacitor, and i believe that it is
possible.
>But i'm worring about the design. infact, every single plate is already
a little
>capacitor "as is",  and if  i'm right , the thickness of the fiberglass
will be 1.6 mm,
>that is very big (this will lead to a high punture voltage resistance ,
but low capacity). >So , how should i connect the plates one to another
in parallel cinfiguration trying to
>avoid any "corona" , and external spark? and so on, considering that
the plates will be in >a number of 20-40 and i cannot overlap them due
the double face!!!

Any ideas?

bye bye


----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Wednesday, March 01, 2006 5:53 AM
Subject: Re: rolled cap blowew out


 > Original poster: Chris Estes <estescc@xxxxxxxxxxxx>
 >
 >
 >
 >
 > Tesla list wrote:
 >
 >
 >  >Original poster: Adriano.Mollica@xxxxxxxxxxx
 >  >
 >  >
 >  >Hello list,
 >  >
 >  >after the last attempt to start the TC using lithuanian capacitors,
>  >that used to explod very quick and very often, i made a homemade  >
>rolled polyethylene cap.  >  >The dielectric thickness was 0.4 mm,
since 1 mm should resist 60kv, i  >  >thought that 0.4mm should handle
about 25kv.  >  >After the rolling up of the materials, i dip the roll
into a tube  >  >filled with synthetic engine motor oil, and by a vacuum
pump i  >  >removed all the air inside.  >  >  >  >unluckly, after few
successful sparks, the capacitor stopped working  >  >and started to
make a noise (probably an internal arc).  >  >i'm pretty disappointe
'cause i spend around 40 euros in materials,  >  >and many hours of
work!  >  >  >  >how can i built a cheap, reliable, and FAST pulse
discharge capacitor?  >  >  >  >i'm thinking about planar caps in air (
at least is the cheapest  >  >dielectric i know.!  >  >  >  >any
suggestion?  >  >  >  >how much is the dielectric costant of the air,
and its puncture voltage?  >  >37 nF cap wil probably be very large?  >
>thanks!  >  >  >  >  >  > I've just finished an interesting design
thats yeilded about 6.7 nf  > with I'm guessing 50 Kv strength. Its a
stacked plate cap that uses  > corrugated cardboard and mineral oil for
the dielectric. I place 2  > pieces of cardboard between each plate to
give about 250 mil (3/4 cm)  > spacing. All the pieces of cardboard are
oriented so that when looking  > down on the stack you can see through
the corrugation if that makes  > sense. then i place the stack in a
container and fill it with oil. The  > orientation of the cardboard lets
the air bubbles flow up and out quite  > nicely. The most expensive
component is all the oil and, I believe,  > they will have a 'self
healing' quality. If theres a puncture, all I  > need to do is shake it
around to jostle the oil a bit. The dimensions  > are about 20cm by 35
cm by 35 cm for, as I said, about 6.7 nf. If you  > wanted more farads
in less space then you could probably just use one  > layer of cardboard
but I just needed about 7 nf for my NST resonant  > condition and wanted
to be sure about the dielectric strength. I  > haven't tried this out
yet as I'm still building the rest of my coil  > but I can't see any
serious flaw in my design so far. Good luck and  > happy coiling.  >  >