Re: Bang size and break-rate

To: tesla-at-pupman-dot-com
Subject: Re: Bang size and break-rate
From: Finn Hammer <f-hammer-at-post5.tele.dk> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Fri, 11 Jun 1999 22:42:18 -0600
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme
Tesla List skrev:
> 
> Original Poster: FutureT-at-aol-dot-com
> 
> In a message dated 99-06-10 04:47:31 EDT, you write:

Thanks for your thorough responce, I`l answer this one, because there is
so much more, see below:

> > topload 2-3 times bigger than sec. self-C
> 
> This would seem about right, are you suggesting something different?

No, this is what I consider recent knowledge.
> 

> Cheers,
> John Freau

Ok, the first coil I made was heavily inspired by R. Quick`s texts about
the perfect primary, and his descriptions of the transfer btwn. the
primary and the secondary. What he wrote, is that with many primary
turns, that are so spaced, that the outside diametre of the primary is
approx. equal to the length of the secondary, would enable the magnetic
field of the primary to completely engulf the secondary. This would
ensure an efficient transfer of power from pri. to sec.
I see no contradiction here, my coil can make sparks around 3 times the
length of the primary.
What R. Quick also pointed out was, that if the primary was smaller,
there would be a problem with interturn sparks. Initially, I thought
this would be because of the transfer caracteristics of the small coil,
but there is another way of looking at it:
Asuming the coils are run with a 100 BPS rotary (50Hz), and the cap is
sized to be resonant, then the cap will be quite small, therefore the
pri. coil must be big, and the power throughput small also.
So a big primary not only ensures secondary magnetic engulfment, it also
ensures low power input at 100 BPS. (50 Hz)
Terrys recent post about calculating power in, filled in the missing
piece:
Take my 20 kV, 3 kW pig for an example: Resocap:0.0199 nF
At 100 bps it will take 0.5 * 28200^2 * 20e-9 * 100 = 795 watts to
charge the cap.
I am using a 34 nF cap, which charges with: 1351 Watts, so It would seem
probable that with a static gap my coil is running 200 - 300  BPS with
the power available. (Based on the sound, it is running 300 BPS, it
changes pitch 2 times, when I turn the variac up) But with a rotary, all
I would gain with this power would perhaps be a ring of fire in the
rotary.
The sizing of the cap for most beginners is made by the various tesla
programs, but it seems like I would be doing better with a 80 nF cap, to
match available power to 100 BPS.
Now this would bring the primary down from 15 turns to 7.5, still not
too few, however, if I was to change the transformer to say 10 kW, the
cap would have to be 200 nF and this would translate to 4,5 turns
primary. I would assume There would be a problem, then.
But would it be a problem due to power throughput, more than a problem
of magnetic coupling?
So maby RQ was just trying to preserve the coils from abuse?
What to do:
I _must_ get the scope to record breakrate. 
I _must_ get confirmation that the reso-cap estimate should be taken off
the tesla programs, and replaced with calculations based on actual power
throughput ability of the cap.
Find out if it is possible to predict the coupling of the coils, without
actually building them.
And be happy I am part of this forum :-)

BTW: coil described is on display at:
http://home5.inet.tele.dk/f-hammer/tesla/tesla.htm

Cheers, Finn