Re: 120 vs 240 bps, was Rotary phase adjustment

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

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

In a message dated 4/20/01 7:44:24 PM Eastern Daylight Time, tesla-at-pupman-dot-com 
writes:

>   Perhaps a naive question, but is the advantage of one break rate over 
>  another?  Can other multiples of 60/120 be used as well?
>  
>    Thanks.
>  
>  ---
>  Kent Vander Velden

Kent, all, 

I've found 120 bps to be 20% more efficient than 240 bps or higher 
breakrates in my work.  By efficient, I mean 120 bps gives longer
sparks for a given input power in an optimal coil design.  I've tested
these ideas only up to 1500 watts or so.

In a couple of tests I did at 60 bps, the "efficiency" was almost
as good.  The problem with going too low in bps is that the
sparks tend to lose coalescence, and break up into a lot of
small sparks.  This happened when I tested 30 bps.

In general, a low bps will demand a larger toroid, due to the
larger bang size at low bps.  Higher bps can give a longer spark
for a given toroid size and secondary size.

The secondary needs to be larger when using a low bps 
because of the larger bang size.

Other sync multiples of 120 bps (or 100 bps) can be used.
Also, any non-sync bps can be used, but these non-sync
break rates may tend to destroy NST's.  The non-sync
breakrates are better suited to pole pigs, or PT's or other
non-current limited transformers.   These transformers
work fine with sync gaps too of course.

One of the advantages of a non-sync gap is that the breakrate
can be varied to optimize the system.  Using a sync gap,
the system has to be designed to be optimal beforehand.
The capacitance value of the capacitor is much more critical
with a sync system.  Low bps requires a larger capacitor for
a given input power and spark length.

Another advantage of a non-sync system is that the sound
and behaviour of the sparks changes as the breakrate is varied,
thus adding an element of artistic interest.

I've been using only 120 bps sync lately because of the great
"efficiency".

Cheers,
John Freau