The Turn Of The Century Electrotherapy Museum
(C) Jeff Behary 2007


Spark Gap Tesla Coil operated from 220/240V mains without a transformer

Tesla wrote in his early lectures that he was able to sustain a spark gap with as little as 200 volts.  Here's proof.

This gap was adjusted from .0015" - .0005".  A simple choke coil was placed in the circuit to limit the current from the 220/240V mains.
A .15 mfd condenser wsa placed in parallel with a spark gap in series with the Tesla Coil.  A normal circuit only without a transformer.

Sparks were not long (.75"  - 1.5") but were extremely hot.  Equivalent spark of a diathermy machine yet only 240V 1000mA  input power.

Click here for a movie!

Output was seen as a thin straight spark surrounded by fiery flames that radiated a lot of heat.

At maximum spark distance the spark tends to form a ribbon of sparks / flames.

Single Bovie Spark Gap and Electromagnet / .15 MFD Condenser

5" Pancake Coil - 1000T Silk Covered Secondary (32 AWG) and 6T (10 AWG) Primary

A 240V spark gap driven Tesla Coil is not impossible, but requires a precision tungsten spark gap.  However, by
increasing the voltage to only 300 - 750V much easier results are obtained and a normal spark gap is more easily sustained.

It is also curious to note that a .5 mfd condenser can be used and a normal "model T" ignition coil replaced with the Tesla Coil.  The whole coil
must be submerged in oil and an amazing 2" flaming discharge will result.  Photos tommorrow!