Re: [TCML] vacuum tube coil

[FutureT@xxxxxxx]

In a message dated 11/13/2007 7:19:50 P.M. US Eastern Standard Time,  
mrclivehansen@xxxxxxxxx writes:

Hello,
Does anyone know what the distinct advantage of  a vacuum tube tesla
coil? I have seen a lot of hype regarding these and  cannot spot the
advantage. I am thinking about building one, however, I  just want to
know why they are better (or worse) than a traditional coil  design
with a spark gap. I found this schematic which is the one I  am
considering.  http://research.microsoft.com/~swinder/sparks/tes2circuit.jpg

-Clive



Clive,
 
For longest sparks for a given input power, tube coils offer no  advantage.
This is because tube coils require at least 4 times more power input
for a given spark length as compared to spark gap coils.  
 
Tube coils are very different than spark gap coils.  They work  differently,
and the sparks have a different character.  They are also much more  difficult
to build, unless you follow an existing design carefully.  Even then,  much
more work is involved.  Also the parts count is much  greater.  
 
I wouldn't say that tube coils are better or worse than spark gap  coils,
they are mostly different.  An advantage of tube coils (or VTTC's) may  be 
that
they can more easily light nearly fluorescent tubes or other other  gas-filled
bulbs. 
 
There is a way to get longer sparks from tube coils by pulsing them  in
what I call the staccato mode.  This gives an interesting rat-tat-tat  sound,
and a pulsed visual appearance.  A separate circuit is needed to  accomplish
this staccato action.  
 
I show some tube coils at my website at:
 
  _http://hometown.aol.com/futuret/page3.html_ 
(http://hometown.aol.com/futuret/page3.html) 
 
I eventually improved the staccato controller, and this updated  controller
schematic can be seen at Steve Ward's website.  It includes a  zero-crossing
circuit for better triggering of the staccato.  There's also some  other info
on tube coils at Steve's website.  
 
John



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