The Turn Of The Century Electrotherapy Museum http://www.electrotherapymuseum.com New Tesla Coil With New Spark Gaps A Compact Modern Breadboard Tesla Coil made with modern materials 9kV 60mA Transformer, 4 Series Behary Spark Gap, 3 .002 mfd Doorknob Caps, Tesla Coil The base is 1.25" thick Acrylic Caps wired for .006 mfd at 40kV.  Vintage rubber coated wire used here! Tesla Secondary Coil is removable - rests on the top of an original ceramic Edison Battery Jar Lid courtesy of Robert Campbell! I think this will be a great surprise at lectures.  Primary is 5 turns of 1" Copper Ribbon, separated by .1875" thick EPDM rubber. Secondary is wound with 250 turns of quadruple-silk covered magnet wire, 30 AWG.  Closeup of winding.  Secondary is 4.5" OD and 9.75" of winding. Approx. 26 turns per inch. Topload is a 6" Copper Sphere.  Discharge point made of a brass bell and 3/8" diameter ball terminal. Arcs to metal rod Brush discharge Click here for a movie! Brush discharge exceeds 12".