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Re: 20 joules at 100 bps vs 4 joules at 500 bps - any difference?

Original poster: FutureT@xxxxxxx

In a message dated 7/13/05 2:32:01 PM Eastern Daylight Time, tesla@xxxxxxxxxx writes:


so, what does the spark`s length influenced by - power or bang size?
you both are saying that bang size does, but look here:

<http://members.aol.com/futuret/page5.html>http://members.aol.com/futuret/page5.html

"In a well designed TC, the spark length will follow the formula:
spark length (inches) = 1.7*sqrt input power (wallplug watts)"

there`s no connection with single discharge energy here, but i know, this
equation
works and works well - that`s why i`ve asked my questions.




The equation works OK from break-rates of around 60 bps to
maybe 300 or 400 bps it seems.  It's possible that larger coils
may better tolerate the higher breakrates toward the top of that range,
but lower break rates should still be somewhat better.  There
are still some unknowns here.....


John - how would you comment your own  equation? in this way:

"Any coil that gives a certain spark length at a high bps, can be
redesigned to
give an even longer spark for the same power input at a lower bps"
?



Yes, this was in response to a great many folks who used to
install a 120 bps SRSG without adjusting their cap value.  Since
they had a small cap, and were previously running at a high bps, they
actually lost spark length when they went to 120 bps.  They
argued with me that they disagreed that 120 bps was better.
My comment was part of my explanation of why they needed
to follow the rules for building a 120 bps coil and use a larger
capacitor value.


but it`s not similar to Terrell`s words:

>the 20 Joule system should have arcs SQRT(20/4) = 2.236 times longer.

_too_ large difference. 


I haven't seen too much difference in spark lengths between
120 bps and for example 400 bps for the same power input.
Maybe it was a 20% or a 40% difference but I forget offhand.
But I did do some comparisons that I can look up.  I seem
to remember that using a cap value increase was twice as
efficient at producing longer sparks as a bps increase was,
assuming equal input powers.


p.s.
i`m disturbed by the following: at 100 bps i have too heavy currents in the
primary
circuit - 1200 a peak and approximately 10 a rms - there would be some
problems with a capacitor & large loses in the wires.
and it`s only 2 kW!!! what can happen at 5 kW or 10 kW at 100 bps -
terrible %-)



All those heavy currents should not be a problem.  The losses
should not be too bad.  By using
a large number of secondary turns, and/or a wide secondary, it helps
to keep the primary inductance high, and the peak currents lower.

John