Re: [TCML] MOTkenstein

[Scott Kraus <plymouth_4406@xxxxxxxxx>]

I once dismantled a dead 10 kva 14.4 kv. pig. I think the core was at least 25 square 
inches and 4 volts per turn. Considering how well built they are you might get 5 volts per turn but that should give some idea of how much iron you need.
 
 Also tried the two mot secondaries with one primary and clamped the cores together. It does work. That idea was the result of a cold, boring Wisconsin winter.
 
Scott

--- On Mon, 7/28/08, Christoph Bohr <cb@xxxxxxxxxxxxxxx> wrote:

From: Christoph Bohr <cb@xxxxxxxxxxxxxxx>
Subject: Re: [TCML] MOTkenstein
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Date: Monday, July 28, 2008, 1:29 PM

Hello Folks.

Most important things are said, but for the fun:


>     I was planning on buying a Pig shortly anyway, but here's another 
>thought then, take the middle out of two MOT cores, and stick them 
>together sideways, now the cross sectional area is doubled.
With 4 cores , 2 sideways and than the two E-Packs facing each other,
you would double the core section, thus the power handling. However
construction problems ( tight gaps ) might become even more critical.
Also, this will increase wire length.

>  As far as 
>not having enough turns on the primary, yes this would probably draw 
>10,000 amps shorted, and would need really really heavy ballasting,
With a 20 turn primary it might easily draw 10KA with the secondary open ;-)
A Core with a 5V/turn ratio would have to be quite beefy.. aka
"NotAMot"
The problem you are facing is saturation, you don't even need a secondary 
to run into trouble there. I had good experience eperimentally determining 
the Volt/Turn ratio as suggested to me by FinnHammer. ( without whom
my xformer wouldn't exist anyway )

>could use more primary rolls, but I was concerned about space,
this might be a problem and will end in an tradeoff between space and
wire size. Might even influence the power handling, after all you have to
have some minimum insulation for you HV even under oil ( looong story )
However, you will by any means have to wrap a tight package.

>and lack the patience to wind a 6000 or so turn secondary.
Patience, wackiness, whatever. I did it with over 10000 turns,
manually wound and counted ( I should really get a life ;-)
others have done far more... you have to know for yourself if you want
to find the "Zen" of transformer winding ;-)

>  The cores would be 
>welded together to prevent vibration and limit gaps between cores.  I 
>think I will try it when I get some time, just for kicks.
I alway appreciate it, when folks go for the "hands on" experience,
but
you should still collect some transfomer design knowledge to keep you
from wasting time building an useless, expensive doorstop.

Another probably working, but somewhat pointless, variation of the theme:
Get two identical MOTS, perferably higher voltage types. Prepare the cores
as you suggest but keep the windings intact ( heater can be removed )
In this core insert one primary and two secondarys, this will give you
double voltage ( watch for insulation, maybe arange coils like an NST does )
Wattage of one MOT, voltage of two, size somewhere inbetween.
After all, everything you need comes with the MOTS for free.
Not too usefull, but if you like to experiment.....


best regards
Christoph Bohr
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