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Measuring Spark Distances (fwd)





---------- Forwarded message ----------
Date: Sun, 02 Aug 1998 20:23:33 -0400
From: Richard Staron <rstaron-at-aracnet-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Measuring Spark Distances

Now here is an interesting point of discussion that  I would like to
discuss with the group,
unless it has been discussed before and is resident in the archives.  I
guess what I would
like to see is a common method of measuring spark length that is simple,
easy to
duplicate by all with out using any high tech equipment.

Question:  How does one measure the length of a spark generated from a
Tesla coil regardless
of the way the spark is generated?

The answer seems quite simple until you start looking at all the
variables that could affect spark length.

I guess I should explain how I measure spark length from my coil first.

1.  I place a thumb tack on the outer most diameter of the toroid
pointing
    outwards.
2.  I have made a strike rod that has a 3/4" diam steel or brass ball on
the  end of a 1/4" brass rod
3.  The end of the brass rod. opposite to the ball is grounded.
4.  The height of the ball is set to be exactly the same height thumb
tack.
5.  Measurements are take between the ball and the thumb tack using a
standard tape measure (after the coil
    is off)

In my particular situation, I watch the coil fire and the instant that I
see a VISUAL strike from the
toroid to the ball is comfirmation that I have made that distance.

However I have also noticed that I may have to wait for a while before I
get another confirmed strike.
Was that poor design of my coil or was I just lucky when the strike
occured?  Who knows!

The question is whether, that one strike confirms that distance or not?
It may never happen again!
Should a confirmation be made only after there are say 2 - 3 strikes
within a 60 second period?
Or should we just leave it at that and say that 1 visual stike is good
enough?
Maybe we should be using a sharp point at each end.....one on the toroid
and one on the ground rod...
or should we not use a sharp point at all to prevent breakout.....

I guess what I am trying to get at is whether this group could come up
with a common method of
measuring spark distances that is easy, cheap, harmless and fun!  (I
guess fun is the most
important part of this!)

Oh by the way, the longest spark that I have attained is 34" using
15KV-at-30ma / .005ufd / 4" D x 18 " / 22G wire
2 gap static gap /  and that is using my method of measurement.   I am
trying to improve that distance without going
to any RSG.  I guess only fine tuning will get that distance
increased...or maybe a large fly will fly between the
toroid and strike rod to increase my strike distance :)

Looking forward to an interesting discussion.



--
Regards

Richard Staron,  VE3FAC
http://www.aracnet-dot-net/~rstaron