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Oudin Coil Detail Specs (yeah, right!)
---------- Forwarded message ----------
Date: Wed, 8 Oct 1997 17:29:55 -0400
From: Thomas McGahee <tom_mcgahee-at-sigmais-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Oudin Coil Detail Specs (yeah, right!)
----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Oudin coil
> Date: Wednesday, October 08, 1997 3:06 PM
>
>
>
> ---------- Forwarded message ----------
> Date: Wed, 8 Oct 1997 17:06:49 +0200 (MET DST)
> From: anjorsta-at-online.no
> To: tesla-at-pupman-dot-com
> Subject: Oudin coil
>
> Today, I found the article about the coil on www.noah-dot-org/x-ray. It
does not
> say how many layers the windings should be distributed in. And not
much
> about the thickness of the insulation between the windings (5000)
either.
> Any suggestions on this?
>
> Atle Jorstad
Atle,
I don't have my original notes anymore, but I remember that when I
made mine the secondary came out about 4 inches long and fit neatly
inside a 3" diameter bakelite tube. Today we would use acrylic or
pvc, with the PVC being cheaper and easier to find, and also easier
to work with.
As you noted, the original article did not give 100% complete details
as to dimensions, etc. But we didn't *need* every single detail. We
got *enough* information to figure out the rest on our own.
I couldn't find the varnished cambric stuff, so I used kraft paper
soaked in beeswax. Got the beeswax by getting the pastor of the local
church to give me all the old candle stubs he had hanging around.
(Hey, you can scrounge stuff *anywhere*). I built a double boiler
from some aluminum containers and melted down the beeswax, removed
the extraneous matter such as wicks and carbon junk by filtering the
beeswax through several layers of an old "T"-shirt. I then soaked the
kraft paper strips in the molten beeswax for about an hour. Why an
hour? Seemed like long enough to drive out any moisture, and I was in
no big hurry, anyway.
No one told me how wide to make the strips. I just looked at the
drawings in the book, and guessed on probable sizes based on clues
like the 1/2" plastic rod. The book mentioned a few things that
didn't seem quite right. The drawing made it look like the wire was
on the outside of the plastic rod. The article mentions a solid
plastic rod, but I used a hollow one, and ran the wire up the
*inside* of the rod. I didn't use any transformer oil or a chrome
chair glide either. They seemed superfluous to me. I mounted a bolt
on the end of my plastic rod so I could attach things later.
I improvised. I allowed 1" margins between the edge of the windings
and the edge of the kraft paper. I simply wound as many turns as I
could within the 2" of actual winding width I came up with. Seemed
reasonable. I had to figure out on my own how to get the wire from
one layer up through the waxed kraft paper and begin the next layer.
(You act like you're continuing the winding as you insert the kraft
paper and wind/wrap it around at least 1 1/2 turns to ensure proper
overlap). Each layer needed it's kraft paper custom cut, as the
layers grew larger and larger in diameter.
Before applying the wax soaked kraft paper I would stick the paper
between some old newsprint and go over it a couple of times with an
old iron. That made the kraft paper nice and flat and easy to handle.
I kept winding layers until I knew that it was getting almost too big
to fit inside the bakelite tube.
Was it 5,000 turns exactly? Of course not! I realized that the
important thing was to have a high ratio. A thousand turns either way
wasn't really going to be that important. There are times when you
want to have an exact number of turns. This was not one of those
times.
Then I soldered a bigger wire on the top layer wire, carefully
maneuvered the wire through the appropriate hole, and then slid the
assembly together. One side of the bakelite tube was open. I turned
this end up, and poured molten beeswax into the interior in an
attempt to make the thing a bit more corona-proof. I could have done
a better job in many ways. But it was good enough, and it worked. I
will not bore you with the details of the copper primary. You get the
idea.
That particular coil was used regularly for almost 30 years. I sold
it, and haven't heard of it since... but I'm sure it's still
operational. Ugly but functional.
Don't fret the small stuff. Understand what is important and what
isn't. Modify where necessary. Scrounge stuff everywhere. If you make
a mistake, learn from it. The most important thing is *DO IT*. Don't
sit around waiting for a complete set of detailed plans. Make your
own!! And share what you learn with others.
Hope this helps.
Fr. Tom McGahee