RE: Silly question?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Loudner, Godfrey by way of Terry Fritz <twftesla-at-qwest-dot-net>" <gloudner-at-SINTE.EDU>

Hi Luc

The site that shows the homebrew pig is located at
http://www2-dot-netdoor-dot-com/~maxz . The core is constructed by gluing together
the cores of small transformers. I collected a pile of transformers used to
supply street vapor lamps. The power company here does not care if you dig
in their dumpsters. The cores are easy to get apart with a hacksaw. I made a
good size square core by spot welding the cores together. I experimented by
using the existing primaries. By using a secondary with about 20 turns, I
found that the voltage output varied a lot when I changed the position of
the coil. I concluded that the performance of such a core was too erratic to
predetermine a set of design parameters. Also the core had a number of hot
spots during operation. Even though I made the core very uniform, it
probably had a complex of eddy currents. I am willing to bet that the wave
shapes of the output did not look anything like those of 60 cycles/sec. The
charging of a tank cap would be very erratic. In fact the owner of the site
e-mailed me that the transformer worked, but it blew his tank cap. I don't
know if rectifying the output of such a transformer would improve very much
the charging of the cap. By the way, it took the owner of the site 14 months
to hand wind the secondary.

Godfrey Loudner

> -----Original Message-----
> From:	Tesla list [SMTP:tesla-at-pupman-dot-com]
> Sent:	Wednesday, September 26, 2001 11:14 PM
> To:	tesla-at-pupman-dot-com
> Subject:	Re: Silly question?
> 
> Original poster: "Luc by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <ludev-at-videotron.ca>
> 
> Hi Matthew,
> 
> No it's not a silly question, but I could show you some reason
> why most of us don't build trans. First the difficulty to find a
> core and don't think about making one with steel sheet; trans.
> mfg. used a special kind of alloy commonly call silicon steel not
> so expensive but hard to find; they are the only one using this
> stuff, the sheet received a surface treatment to make it no
> conductor, this surface treatment need to resist to kind of high
> temperature. If they don't build the core this way the loss are
> incredibly high. An other thing; the mfg. wind there coil in a
> way that the oil could circulated in it, pig are nice piece of
> engineering.
> 
> BUT...! But some do what you plan to do, I remember a member of
> this list, a Finnish I think, he made a core, he build a form in
> Plexiglas and fill it with small piece of microwave trans. core 
> glue together with epoxy. I don't know what was the result may be
> other member have better memory than me. I'm a kink of "do it
> your self" guy but for a big trans. no thanks.
> 
> Often you can find a nice core from a welding machine but the
> window are to small for high voltage coil remember in a HV coil
> you need a lot of insulation and this take place.
> 
> I try to find one here in Quebec Canada but no success for now
> they are easy to find used in USA for around $ 300.00 to $400.00
> but could you imagine the cost of shipping and I don't know about
> the custom charge....
> 
> Cheers,
> 
> Luc Benard
> 
>         
> 
> Tesla list wrote:
> > 
> > Original poster: "Matthew Smith by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <matt-at-kbc-dot-net.au>
> > 
> > Hi All
> > 
> > Maybe I've been away from electrical engineering for too long and
> > writing software as made me soft in the head - but:
> > 
> > If sourcing suitable 110/240V --> xkV transformers is such a bind, why
> > not wind our own?  If it's a question of it being too (mechanically)
> > difficult, maybe I (and others) should try to devise a tranny winding
> > gadget - possibly one that's flexible enough to do Tesla secondaries as
> > well...
> > 
> > In my previous engineering incarnation, we were forever getting motor
> > stators rewound and they must be a NIGHTMARE to do compared with a
> > tranny!
> > 
> > Transformers with alternated laminations (ie the ones that won't pull
> > apart) are obviously out of the question...
> > 
> > If anybody's seen the little widgets on sewing machines that fill the
> > underside bobbin, maybe something based on that principle?
> > 
> > Cheers
> > 
> > M
> > 
> > --
> > Matthew Smith
> > Kadina, S. Australia
> 
>