The Turn Of The Century Electrotherapy Museum http://www.electrotherapymuseum.com Reproduction Kinraide Induction Coil - Full Size Reproduction High Frequency Induction Coil using concepts patents by Thomas Burton Kinraide in 1897 Complete unit, runs from 110V, less than 2A input power. Unit has 3 primary windings of copper ribbon to allow minute variations of electrical discharges from both poles of the coil. Micrometer spark gap is adjustable in 1/1000th of an inch increments.   The smaller centre-punched holes represent increments of 1/10,000th of an inch. Secondary coil has 2000 turns of 34 AWG wire.  A capacity of .05 mfd is used. Sparks are better than smoke... Discharge is adjustable from 6 - 8".  The discharge length can be increased, but sparks tend to form on the insulating tube! View with the lights off. 3 turns of each outer primary coil are used for this photo. (C) Jeff Behary, 2010