The Turn Of The Century Electrotherapy Museum

Jeff Behary's Universal Tesla Coil Tuner
C) Jeff Behary - 12. April 2008

"How does he do it?".  Like this!

The heart of this tuner is my "Binary Condenser" or "Binary Capacitor".  It is a simple Tesla Coil cap tapped at
various points - 1, 2 , 4, 8, 16, 32, and 64 plates pairs.   Each pair of plates represents .001 mfd... so that
this cap is tapped at .001 mfd, .002 mfd, .004 mfd, .008 mfd, .016 mfd, .032 mfd, and .064 mfd.  Any
combination of these values forms from .001 - .127 mfd.

Here is a side view of the knife switches to change the capacity.  They put one or more of the caps in parallel with the circuit.

Here is a side view.  The cap is made from 8.5 x 11 clear acetate, "Overhead Transparency" film.  Cheap and effective for a kilowatt or more.
Two microwave oven transformers, current-limited properly, can supply 4000V at 300 - 500mA.
Many thanks to Frank for the wonderful vintage automobile asphalt-based wire-wrap.

Quality control, My cat Io is checking out the connections!

A close view of the cap connections.  Simple aluminum foil.  Many thanks to Chris Schumacher for the laser-cut steel plate to sandwich the cap!

Here is a wiring diagram of sorts to show the concept.  These figures represent most every possible Tesla Coil frequency used from the 1890s - today.

Testing an 18" tall coil.  Sparks 18" to ground, or the spark gap in this case.

The spark is dimished here, because the frequency wasn't perfect...

Once resonance is established, the discharges become quite interesting...

By changing the frequency slightly interesting things can also happen.  Here you see the ribbon discharge in a spiral to the right!

(C) Jeff Behary 2008