Re: transformer theory q

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

Original poster: "James T by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jamest2000-at-att-dot-net>

Hi Peter,
  My comments are mixed in.

>         primary current to increase (at least when the secondary is unloaded,
>         not so sure about the loaded case).

 In the loaded case you are just adding more current to the ammount already
in the primary causing it to
run even hotter.
 Don't forget as you load the secondary, the secondary's inductance cancels
the primary inductance,
allowing more current to flow in the primary.
 Bottom line: to few primary turns makes a wimpy, hot transformer. Been
there, no real benifet in
increased voltage at reduced current. Its not the voltage, its the current.
Ask the MOT guys. :-)

> I still have not heard a clear answer to part 2, what happens (to the primary
> current) when there are more than the recommended primary turns (take +10%
> as an example).

 I did this. I didn't extensivly test this but the effect is a "self
ballasting" transformer, so to
speak. However I used 50% more windings. What I had is a very large core
that only required 76 turns to
fully magnetise the core. It was no problem to add taps at 80, 100 and 120
turns. This thing produces an
awesome Jacobs ladder at 120 turns and pulls a steady 20 amps(primary),
even with the secondarys shorted
through an Ampmeter. You have to have a proper size core to do this. I
guess the secondary inductance
never gets high enough to fully cancel to primary inductance, therefore
nothing melts. Hope that sounds
right to the Gurus.

> I am thinking of trying many taps on a test primary and finding the one that
> minimizes the primary current (in the unloaded secondary condition), does
this
> make sense? If I do this what happens when I put the shunts back in (or some
> fraction of the shunts), or should I do the experiment with the shunts?

 Personally I would make a tappable primary, as is practicle, with the aim
to use the calculated # of
turns. Since you have shunts you should rely on them for current limiting.
 The big problem is to make a nice tight primary out of thick, hard to bend
wire and other probs related
to slop and materials avail.

> thanks,
> Peter Lawrence.
>

 With the care your putting into this so far, you basically can't fail!
Good luck,
 James Cart