The Turn Of The Century Electrotherapy Museum http://www.electrotherapymuseum.com Winding / Making a Replacement Violet Ray Coil... A completed Tesla Pancake Coil giving 1" sparks. Coil is wound with 34 AWG magnet wire.  Primary coil is 8 turns of cotton covered wire. Secondary is 1057 turns, 13 layers of roughly 80 turns per layer. Secondary coil is less than 1" in diameter. Boiling the bobbin and coil in molten wax 26000-24943 = 1057 Turns The layers do not need to be exact, but hopefully better than this one! Bobbin is made from two wooden wheels, 1 1/2" in diameter and a 5/16" dowel bought at a craft store. The interleave material is drywall/sheet rock seam paper.