VACUUM TUBE TESLA COILS
  
 
   
 
This is my original VTTC that gave 36" roaring sparks.  I used a 5kVA,7.2kV pole pig to power the coil.  Raw AC was fed to the plates of the (3) 833A vacuum tubes.  The secondary was 7" by 26" tall wound with 28awg magnet wire.  Eventually the excessive voltage caused an internal acr inside a tube and destroyed it.  Later, I rebuilt the coil using (4) 833A tubes and obtained 38" sparks.  In the later rebuild, I also incorporated a pulsed or "staccato" capability with which I was able to vary the pulse rate of the sparks, thereby creating interesting visual and audio effects.
 
 
    
   
 
   
 
To the right is my small staccato tube coil project which gives a 15" steady or pulsed spark.  The pulse rate is adjustable during operation.  The pulsing gives an interesting "rat-tat-tat" sound, and the spark can take on an interesting single swordlike appearance.  The primary is 6" by 3" high, and the secondary is 3" by 12" wound with 28awg magnet wire, and it is topped off with a small spun aluminum toroid.  The tube is a 4-250A.
    
     
Schematics for this and the above tube coils at David Trimmell's Webpage.
 
     
 
 
Below, we see the same tube coil as above, except I've reconfigured it into a single unit.  Originally there was a power supply module and a separate TC module.  The entire unit now weighs less than the original power supply module, and takes up less than half the space.  Originally I powered the TC with a plate transformer and a 12 amp variac, now I use a level-shifted MOT and a 7amp built-in variac.  This greatly reduces the weight.
  
 
 
   
 
 
   
 
To the right are two photos of the swordlike sparks from my 24" spark staccato VTTC.  The sparks look very similar to this by eye, except they waver around a little.  The coil is powered by an MOT with shunts removed, and uses Dave Sharpe's level shifter circuit.
    
   
     
   
 
my new more stable zero-crossing staccato controller schematic.
    
   
 
To the right is the portable 24" spark staccato (pulsed) VTTC which produces the swordlike sparks shown in the photos above.  The coil can also run as a normal tube coil, and give typical flamelike sparks.  The cabinet is made of wood, 12" deep x 16.5" wide.  The front and rear panels are Lucite.  Power is from a single level shifted MOT.  The coil uses (2) 833A tubes.  The tube plates run a little red at full power steady operation.  A switch on the front panel selects steady or pulsed operation.  A knob on the panel selects the staccato pulse rate.  The secondary is 3" by 12" wound with 28awg magnet wire.  The primary coil is supported by a Lucite pedestal.  The coil draws 2400 watts in full power steady operation.  A small external (7.5A) variac is used to control the coil power during operation.