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Re: MOT for Ballast Question...

Hello Fabs (first name would be nice!)

The setup you describe will work nicely, I use one like that myself,
although the cores are not from MOT`s, but were chokes to start with.
About same size, though.

You should have the same number of turns, as the mot has, and it would
be naturel to use simply 3-4 primary`s off MOTīs in parallell. Or you
could wind your own coil with thicker wire.

With the cores in contact to each other, the inductance of these coils
will be like a mot primary, and they will allow the same current to pass
into a short, as a MOT idling at no load. How far you have to take them
apart is a matter of trial and error. I found out by inserting pieces of
wood between the outside legs of the e-cores, and clamping the cores
together with a carpenters clamp, to stop vibration from the cores. The
vindings may vibrate a bit, so probably you want to fix them to the core
by applying some epoxy or polyurethane glue.

Hope this helps,

cheers, Finn Hammer

Tesla List wrote:
> 
> Original Poster: "M Fabs" <the_machin_shin-at-hotmail-dot-com>
> 
> I asked some time ago about a thought I had for a ballast, and never
> received an answer. I was hoping someone with some experience with variable
> air gap inductors could help out.  I took apart 2 identical Microwave Oven
> Transformers by grinding out the welds, etc... I was planning to put the two
> "E" sections open face to open face, whereby I will have the same current
> capability as a single MOT, but twice the wire winding window area.  Is this
> reasonable?  I was hoping to build a bracket of some kind that would let me
> adjust the air gap between the two core sections, thereby varying the
> inductance (and current limit).  What range of air gap distances is
> reasonable for, say 0-20 amps?  Would it be on the order of 0-2 mils, or
> maybe 0-200 mils? Should this be wound with wire similar to that which
> originally made up the primaries of the MOT's?  How many turns? Same number
> as the original primaries had?
> 
> This is all for 120V 60Hz supply.  This arrangement (or maybe these, if I
> get ambitious and find more MOT's) will be used with NST's for Tesla Coils,
> and other fun.
> 
> Any thoughts, or answers, or even questions would be welcomed!! I don't want
> to find out only after this is built that I missed something very important!
> 
> MPF
> the_machin_shin-at-hotmail-dot-com
> 
> PS: My Allanson 12kV 60mA is happily soaking away in gasoline, pleasantly
> sluffing away the tar I missed when I heated it up.
> I also got my Primary wound, it's on a Lexan disc about 30" in diameter
> (kinda big, I know, but it's Pretty!), with 18 or so turns of 3/8" Copper
> Refer Tubing. For supports I used some strips of Walmart Special poly
> cutting board. I cut holes in the strips, and then trimmed the strips again
> such that the copper tubing just snapped in. I can't remember which of the
> hundreds of Tesla sites I visited mentioned this method first, but Bravo!!!
> The primary was easy to wind; it took about 5 minutes. (Cutting and drilling
> and obtaining a second 50' of tubing notwithstanding...)  I think
> preparation is the key.
> 
> Thanks everyone!
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