The Turn Of The Century Electrotherapy Museum http://www.electrotherapymuseum.com Drum Style Bipolar Tesla Lecture Coil Two new coils.  Secondary Coils are embedded in cardboard forms 6.375" OD and 12" long. This coil used the Kinraide concept of embedding rings of metal for added capacity to the insulated ends of the secondary coil.  These rings are 6" OD 1/4" wall aluminum pipe cut to 1" lengths. The coil in this example is fairly coarse, wound with 29 AWG wire on a 2.375" OD PVC pipe 12" long. (C) Jeff Behary, 2010