Re: To cut or not to cut

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

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

In a message dated 8/8/01 9:55:01 AM Eastern Daylight Time, tesla-at-pupman-dot-com 
writes:

> something I'm still trying to understand ( maybe the rest of the tesla
>  Gurus can help here) why do we
>  need to have a max voltage and controlled amperage? What does this produce?
>  What difference does 240V
>  in to a variac ( 280Vout) into an inductor that limits the current to 10 A
>  differ from 140V and 20A
>  supply??? )
>  the coil still sees 2800 watts approximatley..........
>  
>  Scot D

Scot,

I'm not sure what your question is.  You could of course use
either 140 volts at 20 amps, or 280 volts at 10 amps to power
a coil.  But the 280 volts will be more efficient due to lower
resistive losses at 280 volts assuming equal wire diameters.

If you use 140 volts at 20 amps, your transformer will need
twice the step-up ratio to get the same output voltage to run
the TC.  If you use the same transformer, then your output
voltage will be 1/2 as much, so you'll have to use a tank
capacitor that's 4 times larger to get the same bang size.
This tends to be a little less efficient and will tend to increase
the spark gap losses.

If you use a transformer with a larger step up ratio, less
ballast L will be needed for a given output voltage and
cap value, because the inductance requirements get
stepped up or down also.  (double the step up ratio,
requires a ballast 1/4 the size)

John Freau