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Re: old fashioned triode Tesla coils



Original poster: FutureT@xxxxxxx In a message dated 12/17/05 3:40:41 AM Eastern Standard Time, tesla@xxxxxxxxxx writes:


Dear All,

I am very interested in working out the details of a triode or tube TC,
because I want to compare this method to the newer solid state coil
schematics. Can someone give me a pointer as to where I can find a basic
concept, basic schematic, or layout, for a triode driven interruptor circuit
that replaces the traditional spark gap?

Sincerely,

Miles


Miles,

Tube Tesla coils as traditionally built do not use the tube as
a replacement for the traditional spark gap.  Instead the design
is actually a power oscillator coupled to a secondary coil.  They
run in continuous wave fashion except they usually run on raw
60Hz AC.  The continuous wave operation makes them much
less "efficient" at producing long sparks for a given input power
compared withspark gap coils.  I usually
include an interrupter circuit which permits a selectable number
of AC cycles to be skipped.  This gives the coil a pulsed or
"staccato" type behaviour.  This provides for interesting visual
and sound effects in a sense.  It also increases the "efficiency"
in a way.  Using this staccato pulsing method, the tube can
be run harder when it *is* on.  This results in longer sparks from
a given tube.  I show some of my work at my website at:

   http://hometown.aol.com/futuret/page3.html

I'm not sure what schematics I have at my website.  I had sent
some information to Steve Ward in the past and he may still have
some of this at his website, along with his own subsequent tube
coil work.

Richard Hull of Richmond VA once built a tube coil which used
a hydrogen thyratron to replace the spark gap.  Unfortunately
this provided only for a one-way flow of current.  Thus he was
forced to terminate conduction at the first beat which prevented
a complete transfer of energy and greatly hurt the efficiency of
the system.  He probably could have added a diode across the
thyratron to conduct the reverse current.  He considered using
dual cross-parallel thyratrons but never got around to trying it.

John