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 Marc

The cores are ok for a HV transformer. I have three dental x-ray
transformers with cores of the same oval shape. The HV section is divided
into two coils located on the center leg. Beneath each HV coil is a primary.
Each HV coil has one lead grounded to the core. The x-ray transformers are
essentally NSTs, but with no current limiting features. Contact Mike at
e-mail address arcsnsparks-at-parlorcity-dot-com and ask him to e-mail you his
transformer design engine. The design engine is not on the web. You can down
load Mike's engine that calculates approximate parameters for square and EI
cores. You can consider your core to be an EI core.  

Godfrey Loudner

> -----Original Message-----
> From:	Tesla list [SMTP:tesla-at-pupman-dot-com]
> Sent:	Wednesday, September 26, 2001 11:08 PM
> To:	tesla-at-pupman-dot-com
> Subject:	Re: Silly question?
> 
> Original poster: "Metlicka Marc by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <mystuffs-at-orwell-dot-net>
> 
> Matthew,
> I'm concidering winding a somewhat "super nst" on one of the back to
> back, oval shaped, high silicone steel cores that the 40-1 transformers
> i found are built with?
> 
> http://www.fortunecity-dot-com/meltingpot/syria/1210/id26.htm
> 
> (top of page one with big taps on it)
> 
> 
> They have a 1" x 3" x 12" high x 4.5" inside width gapped cores that are
> gapped in the center (like this -00-) 6 sq. in. center leg. I was
> thinking of winding each oposing hv bobin for the outside legs of the
> "ovals", these would be around 10" long and i could use hevier wire then
> an nst (like 22g or something). then put the primary around the back to
> back center legs?
> With the bobbins being so long, wouldn't the hv stress be lower from
> layer to layer? Wouldn't this help with cooling because they would be
> reletivly thin?
> I was going to wait until i was about ready and then start asking the
> list for advice, I found some long rolls of .030" thick polystyrene
> sheet that is 22" wide by 100' long and clear, I will buy all five rolls
> tomorrow (I also want to build a polystyrene flat plate cap to test in
> tc duty with some?) at $4.50 a roll, i don't want to pass it up.
> I was thinking about using a layer of this between each wound layer of
> the high voltage coils? (if the list thinks it will be a good idea? or
> maybe use epoxy on each layer? (i would like it to be a dry type hv
> trans. when done?)
> It would be nice if i could get around 40kv-at-300ma when finished, would i
> need to use shunts to keep it current limited?
> 
> I never wound an nst style transformer before, but i think this is a
> good core to try it?
> There will be more questions as i get ready, i just hope it isn't a
> wasted effort because the core style is wrong?
> suggestions are apreaciated,
> Marc M.
> 
> 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
> 
>