RE: DIY HV transformer

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Mark Dunn" <mdunn@xxxxxxxxxxxx>


Christoph:

You could wind a new coil for the open core if you have some spare
#14ga or so wire.  I have 60Turns on my core.  With no gap 38 mH.  With
.040" gap 6 mH.

The core is one of the small MOT approx 4-1/8 X 3-7/16 X 2-1/2
I computed Ae = 2218 mm^2, Le = 210 mm, and Ve = 464727 mm^3 if you want
to compare.

Drops about 30 VAC at 14 amps and 60 Hz with the .040" gap.

Mark


-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Wednesday, July 13, 2005 4:02 PM
To: tesla@xxxxxxxxxx
Subject: Re: DIY HV transformer


Original poster: "Christoph Bohr" <cb@xxxxxxxxxxxxxxx>

Hello Mark.

Thanks for your reply.
I already opened a core just as you describe it and the
E and the I part of the core really seprate nicely while
the remaining welds hold the laminnations together. Unfortunately this
transformer had both windings ruined. But I still have a bigger one I
will try to modify this way. It has also a primary failure, but on one
of the outer layers. I think it should be OK to remove some turns
there... I will carry out these tasks in the next few days and report
what happened.

best regards

Christoph

----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Wednesday, July 13, 2005 8:29 PM
Subject: RE: DIY HV transformer


 > Original poster: "Mark Dunn" <mdunn@xxxxxxxxxxxx>
 >
 >
 > Christopher:
 >
 > If one of your MOT secondaries is now shorted then it is obviously  >
ruined.  You can convert your ruined MOT to a ballast inductor.  Most  >
MOT's are made of E and I cores.  The E's and I's are all in the same  >
stack respectively(typically) and welded together along either side.  If
> you saw the weld out then the I cores will separate from the E's.
Note:  > make a thin saw cut down the center of the weld so the weld
remains  > intact to hold the separated E's and I's together(or add new
weld on  > either side of the the originals).  Once apart, remove the
secondary  > coil and use the primary as the inductor coil.  You can gap
the E and I  > stack with plastic shims to vary the inductance.  I can
give you some  > rough #'s on inductance and gap for a given core if you
want.  >  > Mark  >  >  > -----Original Message-----  > From: Tesla list
[mailto:tesla@xxxxxxxxxx]  > Sent: Tuesday, July 12, 2005 1:00 PM  > To:
tesla@xxxxxxxxxx  > Subject: DIY HV transformer  >  >  > Original
poster: "Christoph Bohr" <cb@xxxxxxxxxxxxxxx>  >  > Hello everyone.  >
> As you may have noticed during the last few days, I had some trouble
> with my 6-mot-stack, which finally lead to a failure mode that makes
> diagnosis very difficult, so I wanted to try something else: Wind my
own  > transformer:  > first pictures of the winding process can be seen
here:  > http://www.luebke-lands.de/tesla19.html
 > along with some basic specs.
 >
 > The transformer is intended to be run unter oil, but another problem
> arises:  >  > The core material I am winding this transformer on, is
the core of my  > former ballast coil, which means I no longer have one.
Now, can I  > incooperate some shunts or airgap to limit the current so
that I don't  > have to build another ballast coil? The core is basicaly
rectangular,  > with each of the coils on one leg left and right...
Maybe someone has an  > idea here. Maybe even with shunts, that can be
moved by means of some  > mechanism while the transformer is still under
oil....  >  > I'm thankfull for any suggestions.  >  > best regards  >
> Christoph  >  >  >