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Re: 120 or 240 or 480 BPS??

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

In a message dated 2/3/01 11:17:25 PM Eastern Standard Time, tesla-at-pupman-dot-com 

> Original poster: "Bill Trumpet by way of Terry Fritz <twftesla-at-uswest-dot-net>" 
> billtrumpet-at-hotmail-dot-com>
>  Hello TCML,
>  Would any of you be so kind as to explain to me the fundamental 
>  in the BPS settings for SRSG's?  What can I expect from the different 
>  rates?  What rates are good for what type of XFMR?  How do break rates 
>  effect the cap values needed for best performance? Any and all tid-bits of 
>  info appreciated.
>  Thank you all,
>  Bill Trumpet


Basically, in the work I've done, the 120 bps is the most "efficient"
at producing the longest sparks with a given amount of power input.
NST's seem to strongly favor the use of 120 bps, but pole pigs, 
and PT's (potential xfrmers), can tolerate higher break rates better.

For a given spark length and input power, lower break rates will
need larger caps.  This is because power input = cap energy in
Joules X bps (not counting losses).

A coil using a low bps will need a taller secondary because it
will have  larger "bang" size.  It will also need a larger toroid,
again to match the larger bang size.

I did test comparisons of 120 vs 240 bps, and the 120 bps was
20% more "efficient" than 240 bps.  The comparison was done
by doubling the input power in two different ways.  First by
keeping the bang size the same and doubling the break rate.
This gave a 20% spark length gain.  Next I doubled the bang
size but kept the break rate the same.  This gave a 40% spark
length gain.

The sparks may look more frantic and fast moving at a high
break rate, but this may not be noticeable if a breakout
point is used on the toroid.  

Also, I think at higher break-rates, it makes less difference if
the gap is synchronous or non-synchronous.

More theory at:


John Freau