First Light

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

Original poster: "Kelly & Phillipa Williams by way of Terry Fritz <twftesla-at-uswest-dot-net>" <kellyw-at-ihug.co.nz>

Hi All,

On the 8th Feb we had the "First Light" of our 9" coil. Specifications are:

Power supply: 15kV 120mA NST farm with 1nF filter caps and 3300 ohm
resistors on each leg.
Capacitor: 40nF MMC using Terry's Panasonic caps
Primary coil: 21 turn 254 uH total  flat spiral coil
Secondary Coil : 9" dia. by 45" wound with 24AWG for 2000 or so turns
Toroid: 25" center-to-center dia. and 9" tube dia.

We suspended a grounded wire about 5" away from the toroid with no breakout
bump, and having no variac, we just threw full power to the NST's. We
immediately got a LOUD buzzing from the spark gap, and brilliant white arcs
to the grounded wire! :-)))))))))
We then moved the grounded wire out slowly, and the maximum arc length was
24 inches!!

We then removed the grounded wire, and we could get 5-6 thin purple
streamers about 6-7 inches long from all round the toroid (no breakout
bump). They were very small and thin, but the toroid is very scrappy (foil
pasted onto a large tractor inner tube).

Our system should be capable of 60" - 80" arcs eventually, and there are
thousands of things to improve (esp. the coupling - the bottom of the
secondary coil was more than 4 inches above the primary coil as we were
scared of secondary flashovers.)

Does anyone know of a method of calculating or measuring when your coupling
is optimum aside of lowering the secondary until flashovers appear?
This is our first coil, so we would like as much advice as possible.

Thanks for all the help everyone has already given us,

Alan Williams and Daniel Mullholland