Re: DC power again

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: FutureT@xxxxxxx 

In a message dated 1/7/06 9:28:45 AM Eastern Standard Time, 
tesla@xxxxxxxxxx writes:


> >From what I have read a larger cap in a properly
> > designed Tesla
> > coil will yield
> > a higher voltage and thus possibly a longer spark.
> > If I increase the cap while
> > also suffering a decline in repetition rate will the
> > sparks actually
> > get longer?
> >   Is a high rep rate necessary for long streamers?
> >


Generally a rep-rate of around 120 bps seems to be most
"efficient" at producing long streamers.  Certainly 160 bps
will give similar results, and 100 bps is OK too.

I once did some tests at 60 bps.  (Actually I did two
series of tests.)
In one test series the 60 bps seemed a little better than
120 bps, and in the other tests it seemed a little worse.
I may have made a mistake in the earlier tests though.
I think the 60 bps is generally not as good as the 120 bps.
In any case the sparks at 60 bps are not generally as "nice"....
not as bright, etc.  If the break-rate is too low, the sparks
will not coalesce and the notorious "gas-burner" effect will
occur with a plethora of tiny short streamers emitting all
around the toroid.

Some coilers especially using pig powered or PT powered
systems like to run variable speed async for a break-rate
of 200 to 500 bps or so.  Often these systems seem to
remain reasonably efficient at the higher break rates.
It is likely that by installing a somewhat larger capacitor,
and keeping the bps around 120 to 170 bps, the spark
producing "efficiency" might be improved.  Some folks
like the brighter more intense streamers that are produced
at the higher break-rates.  However the brightness can
be increased by using a larger toroid when running the
lower break-rates along with the larger cap value.  The
lower break-rates with large bang size often do best
with a somewhat larger toroid.

Generally the design of a 120 bps sync rotary system is
somewhat more critical than an async system.  The cap
value is more critical in the sync system.

All of what I wrote above is mostly for AC powered coils,
although DC behaviour may be similar in many aspects.
(I noticed the post subject heading has a DC component.)

Happy New Year to all !

John