xfrmr rewinding, was: Re: SECONDARY WINDING AND COATING JIG

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

Original poster: "Peter Lawrence by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Peter.Lawrence-at-Sun-dot-com>

Sparky,
       400ma, was that by design or what. Did you just remove all shunts, 
or just some, if so how did you decide how many - trial and error or
computed. Did you actually measure the short circuit current (like Terry
suggests with a voltmeter across a 1kohm (high wattage) resistor shorted
across the output?).

I'ld like to know how to design for a given short-circuit-current, but I've
not seen anything describing how (how to design a non-current-limited power
transformer is described very well in "Roll your own power transformers"
at   http://members.tripod-dot-com/~schematics/xform/xformer1.htm   but this
gives no clue about current-limited transformers.

The power transformer web page suggests #24 to #25 wire for 400 ma (1 to .75
CircMils per ma) for continuous duty. I take it you've not had any problems
with #30 though, presumably since TC usage is typically very very low duty
cycle.

-Peter Lawrence.




>Original poster: "Dukester by way of Terry Fritz <twftesla-at-uswest-dot-net>" 
<>dukester-at-home-dot-com>
>
>Will,
>Been there, done that. I have rewound a Franceformer 15/60, it is now a
>14/300. Works good! I started winding it by hand on a home built winder that
>I made out of  MDF shelving. I was guiding the 30ga. wire by hand, but found
>it too difficult to keep the winding even and not overlapped. I designed an
>auto-feed that was driven directly from the spindle that I could adjust the
>speed of the feed by changing drive wheel sizes. I used a third wheel in
>between the two drive wheels to reverse the feed. It's designed loosely
>after Terry Fritz' winder but without the fancy computer controls. If you
>build one, skateboard bearings work good for all the rotating parts.
>
>Later,
>Sparky