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Re: transformer theory q



Original poster: "Finn Hammer by way of Terry Fritz <twftesla-at-qwest-dot-net>" <f-hammer-at-post5.tele.dk>

Peter!

Too few primary turns, and Your primary inductance will become too  low,
so that the current in the primary will become too high. Connected
unloaded to the mains, the transformer will melt or burn, instead of
idle along nicely.

Calculating the primary turns is all right, but nothing beats actually
testing it: Get a ballpark number by calculating, then wind that number
of turns with _any_ kind of wire you have laying around. Connect to
mains to check how much current flows. The idle current should not
exceed, say 5%, of full current draw.
If the current is too high, wind another 10-15 turns, and try again.

When you get it right, for this particular core, wind a nice and
beautifull primary, with the right wire and all, and you will have a
great start on a transformer.

Cheers, Finn Hammer

http://home5.inet.tele.dk/f-hammer/tesla/tesla.htm

Tesla list wrote:
> 
> Original poster: "Peter Lawrence by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <Peter.Lawrence-at-Sun-dot-com>
> 
> Tranformer gurus,
>                  I might actually make some progress on my mechanical xfrmr
> winding jig over Thanksgiving holiday, so I have a question about xfrmr
design.
> 
> If I follow the design guide at for example
>         http://members.tripod-dot-com/~schematics/xform/xformer1.htm
> I get a certain number of turns in the primary to match the core cross
section
> of the laminated core that I have obtained.
> 
> What if I use fewer turns in the primary to up the turns ratio (I've only got
> so much room for secondary turns in a fixed winding window size).
> 
> What happens with fewer primary turns than "recomended" for a given core.
> 
> thanks,
> Pete Lawrence.