RE: Desktop Bipolar Coil

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

Original poster: "Dave Kyle by way of Terry Fritz <teslalist-at-qwest-dot-net>" <dave-at-kyleusa-dot-com>

Thanks for the comments. I hope I was not misunderstood regarding spark
length; I am only seeking to attain 18 inch sparks from a 2 foot coil. The
calculations were best case with the power level I plan to run to show 18
inches should be possible. Should 7.5KV -at- 30 be too little I can always get
a 9KV -at- 30 and throw another cap on the MMC.

My reason for using the SRSG is that I found a really cool little sync motor
in a surplus store and was looking for something to use it on. Probably
overkill but isn't that why we build these things in the first place. :-)

=========================================
Dave Kyle
Austin, TX USA
Email: dave-at-kyleusa-dot-com


-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Saturday, June 28, 2003 3:05 PM
To: tesla-at-pupman-dot-com
Subject: RE: Desktop Bipolar Coil

Original poster: "Ralph Zekelman by way of Terry Fritz
<teslalist-at-qwest-dot-net>" <gridleak-at-bluemarble-dot-net>


Dave,



Dave,



Me thinks you are a bit optimistic on getting a spark length of 25.5 inches
from a 24 inch bipolar. My efforts with a 24 and 48 inch bipolar convince
me that the geometry of the coil must limit the spark length.



The problem is simply that the spark will always take the shortest path. I
made the rabbit ear antenna arms adjustable so the spark length could be
varied, but no contraption of hinges or ideas of plastic sleeving to
increase the breakdown voltage at the base of the arms succeeded in making
the spark longer than the length of the secondary. As the voltage will
increase with the spacing, the quality of the insulation becomes a factor
in the attainable spark length. While modern materials have increased the
quality of the insulation, I have never seen a photo of a bipolar coil
showing a spark length longer than the length of the secondary.  With 15 kV
-at- 150 mA input,

the best I could ever get is 20 and 40 inches respectively for the 24 and
40 inch coils.



An MMC combo will work just fine.



Good luck on your project.



Ralph Zekelman