Re: Safety FAQ-discharge classification

To: tesla-at-pupman-dot-com
Subject: Re: Safety FAQ-discharge classification
From: "William L. Osburn" <wosburn-at-utk.edu>
Date: Fri, 23 Aug 1996 10:59:20 -0400
Richard,
<SNIP>
>Sorry about the car crash.  Hope you are on the mend.
>
>Oh yes,  We have numerous  video clips of this "hot knot" effect.  
>Because I am in the engineering end of video, this is easily explained.  
>Based on the normal video exposure rate 1/60 sec/field- 1/30 sec for 
>frame (two fields.  You are seeing the banjo effect synced to 60hz--- the 
>normal exposure rate of the camera.  As the scan moves to make an 
>exposure it is synced to something near line frequency in a camcorder. 
>(crystal generated)  Horizontal sparks tend to occur 2-6 times (pops per 
>exposure), and the camera scans the same area, in sync, at a given point 
>along the arc channel three or more times.  Arc channels move almost 
>imperceptively in calm air (air currents-convection).  The parts that 
>tend to move the most pile up video luminance at that point in sync with 
>the 2-6 pops.  Video is not High res and so at some points often as 
>many as 6 along the arc channel a super bright "sync" knot" appears.  
>A video artifact.  We have yet to catch one on a high res B&W 
>closeup photo-- only the banjo strings show up as individual pops.
>At a distance, and with fast, grainy film, even a photo can show this 
>knoting in really calm air. (camera fails to resolve the banjo strings)
>
>Try this at a faster video exposure (1/250th or more) for more fun and 
>games.  At really high rates and just the right sync with line and the 
>gap, the arcs can even disappear at 10,000 watts!  This is most easy to 
>see with a syncronous rotary.
>
>At the normal exposure levels, it is quite amazing to see these "knots" 
>of hot white light move along the arc channel as the non-synced camcorder 
>beats against the line frequency and gap rate which syncs the arc 
>channels.

I have a photograph of my coil (color, 35 mm) which shows the banjo effect
quite nicely.  In fact, there is a spiraling spark which looks like a ribbon
of banjo sparks.  I used a time exposure and you can count the channels.  Is
that related to the break of the gap?  Is my gap set up right?  I was using
a hemisprical head as that is all I had.  I had a small torroid underneath
and the hemisphere on top to increase the top capacitance.  Wish I could
scan it in for you folks to see...

Later,
*** Magic Bill ***