The Turn Of The Century Electrotherapy Museum http://www.electrotherapymuseum.com Inside Out Pancake Coil or High Frequency Unipolar Induction Coil Secondary winding - 9" OD 3.5" ID - 125 turns of 26 AWG Secondary Coil embedded in Paraffin Wax Primary Coil - South African Pinotage bottle - 25 turns of heavy stranded wire Wine bottle Primary inserted into Secondary Coil Testing - 5000V .004 mfd - 3 series 1/4" diameter Tungsten Spark Gap 3 - 4" sparks (C) Jeff Behary, 2007, 2008