Re: Self-built power transformer

To: tesla-at-pupman-dot-com
Subject: Re: Self-built power transformer
From: Doug Brunner <dabrunner-at-earthlink-dot-net> (by way of Terry Fritz <terryf-at-verinet-dot-com>)
Date: Wed, 30 Sep 1998 18:43:57 -0600
Approved: terryf-at-verinet-dot-com
Slight misinterpretation, it appears. I was talking about 8 primary turns.
I would put
the windings on top of each other and parallel them, thus giving me an
inductor with the
same value but capable of handling more current. According to my
information, 32 AWG can
take 1 or 2 amps, and 24 can take 6, so with 5 layers paralleled, it can
take 30. It'll
be in oil anyway, so I have some margin for error.

As for the losses issue, I think I have a solution to it--tell me what you
think. I'd
magnetically couple it on both ends (probably run some thick bolts from the
core) to the
caps of the iron pipe it will be enclosed in. Therefore, I'd have something
like the
double E, except all the way around.

Tesla List wrote:

> Original Poster: ESchulz531-at-aol-dot-com
>
> Doug,
>         How much power are you going to draw from this transformer and
are you going
> to use it for a tesla coil?  I have built my own 29 kV 300 ma transformer
and
> it has worked fine with my tesla coil.  You said 15" long and 1" diameter.
> This implies to me that you are using a cylinder core.  The losses from this
> wouldn't even be funny.  You need to use either a torriod or a double E core
> which looks like a 8 on its side.  If you used your 40 primary turns and
1600
> secondary turns you would have a 1:40 transformer.  So with an input voltage
> of 120 volts you would get 4800 volts.  With those wire sizes you are using
> you wont be able to pass much current through the transformer without
> something melting.  Form my calculations I get about 0.81 volts / (turns *
> inch ^ 2) for the maximum flux in a transformer before saturation.  This
value
> does leave some room for error.  Let me give an example.
>
> Using a torriod with a 5" radius and a 0.5" radius of curvature you get Pi
> inch^2 of cross sectional area of the core.  Now if you want to connect the
> primary to 120 volts you will need 120 / (0.81 * Pi) turns or about 47
turns.
> Now if you wanted 12000 volts form the secondary you would need (47 *
12000) /
> 120 secondary turns or about 4700 turns.
>
> I hope this helps a little.
>
> For information about my transformer go to
> http://members.aol-dot-com/tesla00/o_index.htm
>
> Erik Schulz
>
> >> I'm currently building a power transformer for my coil, and I'd like to
> >> get some reactions on it. It's wound on a 15" long, 1" diameter
> >> commercial iron core with 1600 turns of 32 AWG magnet wire for the
> >> secondary, and 5 windings, 8 turns each, of 24 AWG (they're on top of
> >> each other) for the primary. I'll probably wind a second primary so I
> >> can run it on 240V as well as 120V. The whole thing will be immersed in
> >> motor oil. Please reply with your opinion--I want to be sure it won't
> >> fry on me when I power it up.



--
           --Mr. Postman (Doug Brunner)
                <dabrunner-at-earthlink-dot-net>