One thing that I don't understand is how this would virtually eliminate the
problem of arcing down the tertiary winding. Isn't the base of the
winding being fed with a much lower voltage than is at the top? If this
is true, wouldn't the spark be just as likely (or slightly less) to spark
to the base where the potential is much less?
I got my 4" coil working last weekend some more. I was trying to observe
things and do both some experimentation and some photography.
On the experimental side, I notice that sometimes I get sparks zapping
down the secondary. These sparks are attached to the secondary, and don't
appear to be arcs from the toroid or top turns, but instead seem to be
more like massive static electricity sparks. I have gotten shocked from
touching the secondary when the thing had been off for a few minutes,
so I know that there is the potential to build up large potentials (sorry).
I am using an air blast spark gap, so to shut down the coil, I cut off the
air supply and then turn down the power to the coil. It is obvious that
the air flow plays a critical part in the quenching of the spark. When
the air flow stops, the coil stops. The interesting thing is that as the
air flow is stopping, I notice that there are more static sparks down the
coil than when it is running full tilt. This indicates to me that gap
quenching plays an important role in the creation of sparks down the sides.
Photography: I have an SLR camera with automatic exposure. When I took
the pictures that I'll post (once our scanner gets up and running), the
exposure was adjusted automatically to make the dark garage appear at
daylight values. The end result is that there is a well lit garage with
a sparking coil in it. This isn't as dramatic as a black background.
Therefore, the next set of exposures will be taken as follows:
Bulb setting, apperture wide open, exposure about 1 sec. or so.
I have taken great coil shots, but foolishly didn't write down how I did it.
This weekend I spent my time fixing the air compressor and working on a
vacuum cleaner gap. (The vacuum cleaner motor is in a box which has
the parallel gaps on it. The vacuum cleaner sucks air through the
gaps). I'll give more details as they become available.