High Voltage Power Source is a 9kV 30mA Neon Sign Transformer. 9000V * .03A = 270VA of total output power. Manufactured by Alanson.
Spark Gap is five, 3/4" O.D. x 2" long copper tube sections, epoxied onto a small plywood base with small air gaps in between. Total gap spacing is close to 1/8". No cooling air is used, and the unit gets quite hot after a couple 2 minute runs.
Tank Capacitor is a single "Promised Land" glass milk bottle. The outside has been wrapped with aluminum foil for one plate, the other plate is the saltwater within.
Secondary Coil is a 6" length of #28 gauge Radio Shack magnet wire, wound on cardboard paper towel tube. Outside Diameter is around 2" or so. It is sealed with an alcohol-thinned epoxy solution.
Primary Coil is nothing more than 10 or 12 turns of speaker wire helically wound on a few inches of polypropylene plastic, from a flourescent light protector tube.
Topload Capacitance is a 4" lightbulb covered with strips of aluminum foil tape. The tape was carefully smoothed down so there were no sharp points to limit the output voltage.
Performance: This coil was not built with performance in mind. It was constructed for no other reason than the heck of it. The junk was laying around the shop, and we figured it could be thrown together in less than a couple of hours with a minimum of work. So we did - and we're almost impressed with it ; ) It will give a continuous writhing 3" violet arc to ground, and will flicker a flourescent bulb 3 feet away due to the high frequency. We're really not even sure if it's in tune, but who cares. It works, it's finished.
The whole system:
Primary and Secondary Coils:
Saltwater Bottle Capacitor:
Linear Spark Gap:
