Testing an 8.5" Pancake Coil, Part III


Continued testing of 700 turn 8.5" Pancake Coil (34 AWG wire)...

Sparks could be drawn out 8-10" carefully, but eventually would arc down to the primary terminals as the power was increased...







On higher power, arcs would grow to 12 - 14" or more...

But would still make their way to the primary ribbon!






Later that evening...


Decided to insulate the middle of the coil inside of a 4.5" OD PVC pipe filled with wax...



Low power tests were beautiful 10" crackling sparks

Then on high power some beautiful 14-15" arcs - and as I turned up the current !!**!!** Fizzle !!**!!**!!** !  Almost no brush discharge.
This is why.  The arc broke forth through the wax underneath the coil...

...and even across the wooden table it was sitting on.  More insulation needed!

But...there is no reason why this 8.5" diameter flat spiral coil could not have produced 16" arcs or greater.  I was powering it from 4kV only...
more voltage and moderate power levels might well produce a discharge twice the diameter of the coil...   the problem is insulating it!


(C) Jeff Behary, 2010