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

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: FutureT@xxxxxxx 

In a message dated 7/16/05 4:29:02 PM Eastern Daylight Time, 
tesla@xxxxxxxxxx writes:



>   >Some coils tend to produce a bunch of small short streamers until a
>   >certain bps is reached, then the sparks  coalesce into a single
>   >streamer as the bps is raised.
>
> does this fenomenon give us considerable spark length increasing at
> the same power in comparison with "usual" operating mode or not? that
> is - do we need to aspire getting it in an artificial way?


No it doesn't really give any spark length advantage.  The idea
about coalescence is actually a poorly defined one, because
the coalescence can occur to various degrees.  Certain conditions
can show it up more.  For example in Greg's large coil, he was
able to lower the break rate so low that very short sparks came
off the toroid all around it.  As he raised the break rate the
sparks coalesced into one.  When I ran my coil at 30 bps, it
caused this same "gas burner" effect of very short sparks all
around the toroid.  The break rate was just too low.  In the
normal operation of a tesla coil, the sparks are actually coalesced.
But at higher break rates, the coalesced condition looks a little
different it seems.  One some small coils, just a slight change
in the toroid size can make the sparks look more or less
coalesced.


>   >Maybe if he had a larger bang size, this behaviour would have
>   >disappeared.
>
> everything this could be easily checked with the help of "best man`s
> friend" - drsstc, do you have one? :-)


Unfortunately I never built any solid state coils yet.  That was next
on my list when I got busy with other things.


>   >The components must be carefully "matched for synergy" at 120 BPS,
>   >because there will no longer be the  option to use changes in
>   >break-rate to find the coil's "sweet spot". Rather than adjusting
>   >break-rate to match the coil, the coil will need to be matched to
>   >the break-rate at 120 BPS.
>
> what components? is it not enough just to pick up a large toroid,
> in order to discharge will take place only after full energy transfer
> from primary to secondary?


The matching must be between the cap value and the
break rate.  Using suitable LTR values with NST's will give
the correct result.  Toroid size and overall coil size should
be suitable for the spark lengths expected.  In the old days,
folks used to build a coil "any old way" in many cases.  They'd
simply use whatever transformer and capacitor they happened
to have.  Often the capacitor was of a small value, so a high
breakrate was needed to get much spark length.  So they used
a static gap (which sets the bps rate automatically for a given
cap value), or they used a ASRSG so they could vary the
break rate and find the longest sparks from their system.
I suspect that it was this approach that originally gave folks
the idea that high bps was best.  It happened to be "best"
for their coil because their cap value was too small.


the fact is that i`m now planning my first

> coil, so any component may be changed without any problems - any
> advice? :-)


Only what I said above, but it's nothing new just the normal
LTR, 120 bps concepts.  One disadvantage of the greater
knowledge that's available about coils these days is that folks
often build the coil "correctly" from the start, and never get to
experience the behaviour of less optimized coils.  A variable
break-rate coil could be considered a less optimized coil in
the sense that the user must build the coil, then fiddle with
the break rate to find the longest sparks.  But there are
advantages of variable break rate coils, and many folk still
build them, and their efficiency can be impressive despite
the whole 120 bps issue.  Advantages of the variable break rate
coil are, the ability to change the look of the sparks, and the
ability to change the sound of the sparks.

Cheers,
John