RE: Basic TS curcuit conflict

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

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Gary.Lau-at-compaq-dot-com>

Hi Jonathan:

Assuming that nothing else was changed, the two circuit configurations
_should_ result in identical performance, both in terms of spark length
and racing spark behavior.  The things that affect racing sparks are the
pri/sec coupling and the "bang" size, or the size and charging voltage
of the tank cap.  Changing just between the two circuit configurations
shouldn't affect any of these.  But then I've never tried the other
configuration so I can't be 100% sure that something else isn't going
on.

The reason for favoring the gap-across-the-NST configuration has only to
do with generating the least amount of stress on the NST.  The goal is
to minimize the high frequency oscillations that the NST secondary sees.
The HF oscillations occur while the gap is firing and the tank circuit
is oscillating.  Now, if the gap is across the NST, the gap is
essentially a short circuit when it's firing.  So the voltage across the
gap and hence the NST is minimal.  If the "other" configuration is used
with the cap across the NST, the full amplitude of the tank oscillations
would be across the cap and also the NST.

Terry Fritz performed some detailed experiments comparing the two
configurations and documented the procedure and results in a paper on
his web site.  See:
http://hot-streamer-dot-com/TeslaCoils/MyPapers/primarycircuits/pricir.html

That you're getting racing sparks AND that you blew a tank cap may
suggest that your spark gap is set too wide.  This would generate large
"bangs" and result in racing sparks, and also be very hard on your caps
(and NST).  How wide is it?

Regards, Gary Lau
MA USA



>Original poster: "jpeakall by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<jpeakall-at-mcn-dot-org>
>
>Hi All,
>
>I Have a small coil I have been operating off various power sources.
The
>specs are:
>
>5 1/2" helical primarry, 12 turns of 12 AWG auto wire
>3/12 " secondary, 436 turns of 22 AWG anameled wire.
>
>The circuit I have3 been using is from John Couture's book, and in it
one
>side of the transformer goes to one side of the tank cap, and the other
>trans lead to the other side of the tank cap. One side of the cap goes
to
>the SG, and the other to one end of the primary.  The aligator clip
side of
>the primary goes to the other end of the SG. On other circuits out
there,
>like on Gary Lau's site, the trans leads both go to the spark gap, with
the
>tank caps going between one end of the SG and the primary.
>
>What is the difference between these two set ups? I tried the way it is
on
>Garry's site, and it seems to work better, but I get tons of racing
sparks.
>I had previously been using a .038 tank cap,, and I went down to .021
.014,
>still getting racing sparks. Very little backfire from the safety gap
>however. After a few seconds, I blew a tank cap. 
>
>Is it just that the other circuit is way less efficient, and so I never
had
>the racing spark problems? Is hooking it up as on Gary's site harder on
the
>caps? 
>
>Jonathan Peakall