Re: MOT power supply mot ballast already made

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

Original poster: "colin.heath4 by way of Terry Fritz <twftesla-at-qwest-dot-net>" <colin.heath4-at-ntlworld-dot-com>

hi all
          finn mentioned air gapping a mot for a ballast i have already done
this iv only used the original primary as i havent got around to winding a
new coil for it yet
i use plastic shims to vary the air gap and it will go from 70mH down to
approx 30mH
i have used this to ballast my mots my custom wound transformer and also my
pig the details are at www.geocities-dot-com/colinheath2002/
cheers
colin heath
----- Original Message -----
From: Tesla list <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, November 20, 2002 12:08 AM
Subject: Re: MOT power supply


 > Original poster: "Finn Hammer by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<f-h-at-c.dk>
 >
 > Ted, all!
 >
 > The data was supplied by Helmuth Singer, a German 2nd. hand instruments
 > trader.
 >
 > http://www.helmut-singer.de/
 >
 > The MOT`s in question were wound without bobbins, and the insulation to
 > the core was "MICA-like". That is the best I can describe it. It seemed
 > like a good porous material, which would be able to benefit from
 > saturation in oil.
 >
 > The bobbin wound transformers will be able to get even more oil btwn
 > windings and core, so they are probably even better.
 >
 > I used to have great doubts about the MOT`s to start with, but after
 > having run a 4-pack at length, and reading about the 6-packs, I now am a
 > fan of the concept.
 >
 > A 2pack is a fine alternative to NST`s in a beginners system.
 >
 > The only problem that I see, lies in the ballasting. The ballast should
 > preferably be air gapped, and about the same size as a single MOT.
 >
 > One day, someone is going to have to pry a MOT open, remove the
 > secondary and install a second primary, and assemble the core again,
 > with an air gap in the 1/8 inch 3mm range, and measure the current
 > trough it at line voltage across it.
 >
 > With primary windings in series.
 >
 > This way the MOT project would be complete, and we could recommend the
 > construction of this kind of psu without guesswork.
 >
 > Cheers, Finn Hammer
 >
 > Tesla list skriver:
 >  >
 >  > Original poster: "tesla by way of Terry Fritz <twftesla-at-qwest-dot-net>"
 > <tesla-at-paradise-dot-net.nz>
 >  >
 >  >  >Thanks for this data Finn this is ther very first time I have seen a
real
 >  > rating for core to winding for a MOT.
 >  >
 >  > Still this figure is in air so in oil I'd imagine the stresses of a 4
or 6
 >  > pak could be indefinate. My oil as I recall is rated at 70kv/mm
 >  >
 >  > Whatever the limits are I think good design with 6 paks in oil does not
pose
 >  > a problem from my own experience and judging from reports on the list.
 >  >
 >  > Hate to think of the ratio of dead NST's to MOT's or worse
$NSTdead/$MOTdead
 >  > Best to all
 >  > Ted L in NZ
 >  >  > Typical insulation from winding to the core in a MOT is 7.5kV for 1
 >  >  > minute. It is only a question of how long they last.
 >  >  > This may well be adequate for coiling, and I encourage your attempts
to
 >  >  > find the limit.
 >
 >