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Re: Building your own HV transformer



Hi,
	I have some formulas on my web page that I used to 
make my transformer.  Core thickness mainly.  The rest 
is really variable and up to the designer.  Heres the addr.
http://members.aol-dot-com/tesla00/hbt.htm
Concerning eddy losses:  I use spools of 12 gawg wire 
to ballast my transformer.  By placing a solid steel rod 
in the middle of one of the spools the XL goes up by a 
factor of ~2.4  Running 20a through this ballast for 1 
minute will heat the iron rod up enough to melt the 
plastic spool.  I didn't think eddy currents would be 
so bad the first time I tried this and I almost received a 
bad burn.

	Truthfully the best way to figure out how many volts per turn your core can
take is to wind a simple coil and test for saturation.  This will tell you how
few primary turns you can get away with.  Your core is only power limited by
heat.

Later,
Erik Schulz   <- Gradient
http://members.aol-dot-com/tesla00/
CS major - so lay off of my grammar :)

> Anyway, does anyone have some simple (or not so simple) formulas to 
>  approximate core thickness (laminated silicon steel), primary windings 
> needed
>  to not saturate the core at the wanted VA level, etc. I've found a couple
>  places on the net but the results were so wildly in disagreement that I
feel
>  I need a third (or fourth) opinion. For example, I think I can get a cheap,
>  used 3-phase transformer from the junkyard which has about 3" by 3" core
>  thickness. How much abuse would this take? And I also already have a
smaller
>  typical EI-type laminated core, which has a thickness of about 1" by 3".
>