RE: Re-winding a NST

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

Original poster: "Atkinson, Chip by way of Terry Fritz <twftesla-at-uswest-dot-net>" <CAtkinson-at-Circadence-dot-com>

I rewound one of my NSTs.  I believe I used 31ga wire, which is pretty fine.
There are a number of problems you must over come once you have figured out
the number of turns.  

First, you need to make the wire lay flat with each turn next to the
previous.  With the hair fine wire it is not as easy as it looks.  If you
look at the old windings you'll see that they insulate between each layer.
IIRC I was getting 113 turns per layer.  Then I'd use cyanoacrylate glue to
hold that layer together.  On top of that I'd put a strip of drafting mylar
and glue it down.  You need to use a winding device that has a cross feed
that can reverse.

Another problem you need to address is the mandrel that you wind on.  It
must be close in size to the core but no smaller.  You cannot stretch a
wound coil over a core.  Instead you have to wind another one entirely.
That's the voice of experience.  

Oh, another thing to remember is that as you wind, the wire can break very
easily so you must start out slow and speed up rather than just yanking the
wire.



> -----Original Message-----
> From: Tesla list [mailto:tesla-at-pupman-dot-com]
> Sent: Wednesday, April 25, 2001 12:32 PM
> To: tesla-at-pupman-dot-com
> Subject: Re: Re-winding a NST
> 
> 
> Original poster: "Peter Lawrence by way of Terry Fritz 
> <twftesla-at-uswest-dot-net>" <Peter.Lawrence-at-Sun-dot-com>
> 
> Shad,
>      I'm doing the same thing, with 9, 12, and 15 kv units. 
> Your math looks
> right (I did a similar thing to estimate the existing primary 
> turns, put 120v
> into the primary and measured the output of 10 turns of 
> hookup wire wound
> around the primary). see other comments interspersed.
> -Peter Lawrence.
> 
> 
> >
> >Original poster: "sundog by way of Terry Fritz 
> <twftesla-at-uswest-dot-net>" 
> <sundog-at-timeship-dot-net>
> >
> >
> >Hi All,
> >
> >  Some quick questions about rewinding this thing, so I get it right.
> >
> >I'm using the original primary, but need to make 2 new 
> secondaries for it.
> >It's a 9/30, and I have a 9/60 to do later.
> >
> >with 8 turns of THHN wire on the core, with 8v into it, I 
> get 38v on the
> >primary leads.
> >
> >1 volt per turn means I have 8*38=304 primary turns.  Sound feasible?
> >
> >Mkay.  At 9k output, I have 2 4500v secondaries in 
> anti-parallel.  I got to
> >remember to wind them in opposite directions.
> 
> 
> Make them identical, and flip one around when assembling them 
> on the core.
> 
> 
> >
> >4500/120=37.5:1 necessary ratio for each secondary.  With 
> 304 turns on the
> >primary, I end up with ~11,400 turns on each secondary.  I'm 
> not concerned
> >with getting the voltage dead on, just in the ballpark.  I'm 
> going to stick
> >as close as I can to what the manufacturers (9/30 is 
> Magnatek, 9/60 is a
> >franceformer) originally had on it.  If anything I won't be 
> able to get as
> >many turns as the manuf. and it'll have a lower output 
> voltage.  I'm not
> >concerned with core saturation, as I won't be trying for 
> more than 9kv out,
> >or feeding it more than 120v.  And if it does saturate, ahwell!
> >
> >For potting!  I'm planning on using vaseline, possibly with 
> LDPE melted in
> >with it.  I want to simmer the tranny in the gunk for awhile 
> to give it a
> >chance to seep into all the airspaces it can.  HV oil is 
> just too messy for
> >my taste, and I can't be bothered having to clean it up.  
> petroleum jelly
> >pretty much stays put once it solidifies.
> 
> 
> Don't mix anything into the vaseline, LDPE will not "mix" 
> with it even if
> melted. (I'm sticking with xfrmr oil, and making clear 
> acrylic cases for mine).
> 
> 
> 
> >
> >I wanted to check and make sure I did the math right, so I 
> don't spend an
> >hour or two working on it to end up with a "Doh!"
> >
> >Along the same train of thought, I'd like to use 2 identical 
> cores, wind
> >them with heavier wire to be single-ended (what's the 
> technical tranny term
> >for a 1 eared polepig?) and run them back-to-back like MOTS 
> for a mini-pig.
> >That's a project for another time tho.
> >
> >	Shad
> >
> >
> >
> 
> 
>