The Turn Of The Century Electrotherapy Museum http://www.electrotherapymuseum.com Reproduction Kinraide High Frequency Induction Coil Back: Reproduction Kinraide Coil Front:  Reproduction Kinraide High Frequency Induction Coil One embodiment of Kinraide's patents was to have a coil with a central cylindrical primary coil and two additional flat ribbon primary coils to effect the ends of the secondary coil.  This allowed modifications of the two poles discharges. Sparks at different power levels and frequencies shown below.  4kV transformer, adjustable condenser .032 - .350 mfd used here. Single tungsten spark gap, 1/4" diameter. Note the interesting bright spots on the sparks... Click here for a 4MB movie! (C) Jeff Behary, 2010