Re: ballast core

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

Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <MShock8073-at-aol-dot-com>

In a message dated 4/1/01 3:22:52 PM Eastern Daylight Time, tesla-at-pupman-dot-com 
writes:

<< One of the better variable home made inductors I have made so far consists
 of an E
 core ( 13.5" sqr area ) with 200 turns of # 10 THHN. To make the 
adjustments, I
 slide the windings upwards ( off of the center leg) by 3/4"-1.25". This
 increased
 the current from 15A to 40A. Other methods include increasing the distance
 between
 the E and the I  ( increasing the air gap) for increased Amp flow. >>

I know this may sound dumb, but exactly how do you measure the area of the 
core. I usually think of cores as 3 dimensioned items and that indicates 
volume as opposed to area. But, I see references to square inches. Does that 
mean that the core is measured by height and width of the cross section of 
one leg (IE looking from the 'end')?

Big question: 

How important is it to have the silicon steel from an actual transformer core 
to make a ballast? Can I make a suitable replacement by plasma cutting 10Ga, 
or 3/16, or 1/4 hot rolled plate iron (common sheet metal) into a suitable 
shape, and stacking them into a big enough cross section? If so, then I have 
the perfect situation. I can plug the dimensions needed into my CAD program, 
and use the CNC plasma cutter I have access to, and make my E's from scrap 
material that usually get's sold for pennies a pound to the scrap yard.  I 
could burn a strategically placed hole or two in the corners to use for 
bolting together the laminations or stagger some holes to use for plug 
welding, and have a handy replacement for something I can't seem to find 
elsewhere. Although It might take a while to collect up enough laminations 
from scrap to do the job.

thanks for any info,
Marc S.