Terry's coil picture
Once in a very very great while, lighting, focus, aperture, and those
"funny" knobs, all just seem to magically be in the right place and even
someone with my photographic skills manages to take a really good picture :-))
This picture managed to get everything from the neon to the lower half of
the secondary in excellent detail. The high-res 800k JPG file is at:
I'll describe the parts for those who are interested...
The 15kV 60mA neon is in the bottom of the picture. It is a new Transco
unit I paid real money for.
The output of the neon has two strings of seven 1800 volt transorbs to
ground. These protect the transformer from over-voltage spikes.
The filter network is connected next. There are two 5k ohm 50 watt
resistors in each leg. Then there is a 2700pF 30kV doorknob cap followed
by a common mode choke and two more 5K resistors. There is a piece of wood
on it to hold the red wire away.
To the right of the filter is a high power safety gap. It is set to 11300
volts on each leg to ground. It is made from 1/2 inch machine hardware and
To the left of the safety gap is the fiber probe that is sensing the
secondary ground currents. The orange non-conductive fiber cable is
randomly strung through all the high voltage parts as usual. I shouldn't
have it on the resistor, however :-(
On the right is the 1800 RPM rotary sync spark gap. I can turn the motor
to adjust the timing. A muffin fan cools the motor on the lower right.
The rotor is a thick piece of polypropylene cut from a cutting board. The
gaps are 3/8 inch brass all-thread with the typical hardware. A 3/8 inch
all-thread steel axle has bearings and such held with 3/8 inch nuts and
Above the gap is the primary current sensing fiber probe.
Above that is an array of ten 1.7nF 30kV high-Q doorknob capacitors
between two brass plates which is the usual primary capacitor at 17nF. It
is setting on a sheet of 1/2 thick glass.
The primary has a 12 inch ID with 20 turns of 1/4 inch copper tubing. The
turns have 1/8 inch space between them. The form is a circular pine form
with grooved hardwood supports. The turns are held in place with nylon
cord. The primary is tapped with the large copper strap that has 1/4 inch
fuse clips soldered to it to connect to the tubing.
The secondary has a wood triangle form in it to adjust the secondary
height. The secondary is 1000 turns of #24 space wound on a 10 inch
SonoTube form. It is 30 inches high.
Perhaps this will help answer some of the questions about circuit hookups
and such. You can zoom in very close in this picture to see just about
anything you want.
Hope this is of use...