Re: Practical limit to number of turns on primary ? ? ?

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

Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" <FutureT-at-aol-dot-com>


> >I'm mystified by the repeated emphasis given to the number of turns
> >given that most TC operations are dependent on impedances. For
> >example, the voltage stepup ratio in a disruptive coil is a function
> >of primary and secondary impedances, gap losses are a function of
> >primary impedance and so on....


Hi Malcolm,

Yes, a coiler could build a rather physically large coil and thereby
increase the impedances via coil size rather than a large number of
turns..... A technique which you've used to good advantage on your
impressive coil.  I must admit I haven't had good results using that
method with a 12/30 NST.  It seemed that the large secondary C
value was bottling up the energy too much for the toroid sizes that
were required.

In my writings about using many primary turns, I'm making
certain assumptions about what the designer may want to accomplish.
I'm assuming:

1)  LTR, NST, 120 bps operation (or close to 120 bps)
2)  Low power, somewhat compact design
3)  Low frequency for added "efficiency" (?)

Given the above, a design using a rather large number of primary
turns (18 to 24) generally results.

Larger more powerful coils, higher bps coils, etc, may
not need as many primary turns for a suitably high surge impedance.

I make the distinctions at my website, but sometimes forget to
point them out in a quick list posting.  My apologies.

As you've pointed out many times, best "efficiency" results from
a balancing act between gap losses and wire losses, etc.

Regards,
John