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RE: Transformer cores



Alfred & Max,

I've often wondered about "transformer iron" as well.  I think it contains
lots of Silicon.  It magnetizes very easily in the presence of a magnetic
field, but demagnetizes quickly when that field is removed--for low
hysteresis loss.  Many kinds of cheap wire made of poor quality, high
silicon steel might approximate transformer iron.  I'm thinking of Alfred's
concrete reinforcing wire, galvanized fence wire, coathanger wire,
florists' wire, etc.  I also understand about annealing the wire to make it
softer, to reduce hysteresis losses, but is this strictly neccessary?  How
much loss are we talking about if the core material retains a bit of
residual magnetism?  I know the notion of making a transformer core must
seem nutty to some subscribers.  Still, I'm itching to try it.  The thought
of being forever free from scrounging for NSTs has strong appeal.

Greg

----------
From: 	Tesla List[SMTP:tesla-at-pupman-dot-com]
Sent: 	Tuesday, November 10, 1998 2:23 AM
To: 	tesla-at-pupman-dot-com
Subject: 	Re: Transformer cores

Original Poster: RODERICK MAXWELL <tank-at-magnolia-dot-net> 

Tesla List wrote:
> 
> Original Poster: alfred.skrocki.sr-at-juno-dot-com (Alfred A Skrocki)
> 
> On Sun, 08 Nov 1998 13:03:02 -0700 RODERICK MAXWELL
> <tank-at-magnolia-dot-net> wrote:
> 
> >I have been reading some postings from one of the list members in
> >Australia who has built his own home built pig. I would like to know
> >if anyone knows were to find large laminated iron cores? This would give
> >you the flexibility to wind a transformer to whatever voltage that you
> >like and would be a great learning experiance as well.
> 
> When I was about 15 I wanted a several Killowatt supply for my Tesla
> coils and couldn't find anything close so I got this idea of making a
> transformer core out of iron wire
> used in the construction industry (in concrete work) it comes in boxes
> about 3 feet
> long and may be 4 by 4 inches packed dense with about 18 to 20 gauge iron
> wire. I heated the bundle of wire in a charcoal fire and allowed it to
> cool very slowly to aneal the wire. I then bent the wires into a square
> shape and alternated the sides that the ends came together on. I wraped
> the whole deal in several layers of electrical tape and wound my primary
> on one side and the secondary on the other. I managed to get a fairly
> nice although very bulky transformer that gave me 3 killowatts at 18KV on
> the secondary.
> 
>                                Alfred A. Skrocki
>


   I thougt the iron had to be of a specific type to avoid residual
magnetism (steel will become permanently magnetized)? After you annealed
the wire could you magnetize it by strokeing it with a permanent magnet?
I am familiar with the wire you have mentioned, it is used to tie steel
together in a concrete form.


                                     Frankenstein Helper
                                           Max