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Dead NST
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From: Jim Fosse [SMTP:jim.fosse-at-bjt-dot-net]
Sent: Saturday, February 28, 1998 9:45 PM
To: Tesla List
Subject: Re: Dead NST
><<
>> Hi all,
>> I just picked up a 15 Kvolt 30 ma transformer from a sign shop. They
>> gave it to me as they had it marked with one side bad. I assumed from
>> reading this list that it was probably shorted from tracking. When I
>> got it home and checked it with a meter, that side was open. I poped
>> the top and it is filled to the top with tar. Is it worth trying to
>> salvage this thing, by getting the tar out, when a side is open?
>
>> Thanks,
>
>> Russ >>
>
>Russ,
>
>An open winding seems like a bad sign to me. I needed some "E"s
>one time, so I opened 4 NST's that had open windings on one side.
>All the NST's had one secondary coil burnt to a crisp.
>
>John Freau
Russ,
When I found a 1/4" diameter hole in the winding of my 15kV 60
ma xfmr, I took both secondaries off and rewound with 6.5 turns IIRC
of #4. I can now parallel them for 7 volts -at- 130A or series them for
14 volts -at- 65 amps. I've since added a 300A bridge rectifier for DC.
Not enough voltage for arc welding;( I can just strike a small arc on
a carbon rod. Or using two curved pieces of graphite as electrodes I
can resistance heat metals. It will sweat solder 1.5" copper pipe in
about 30 seconds flat.
As soon as I add a couple more turns of wire on my new secondaries,
I'll have enough voltage to charge 12V lead-acid cells.
cheers,
jim