The Turn Of The Century Electrotherapy Museum http://www.electrotherapymuseum.com (C) Jeff Behary 2010 jeff_behary@hotmail.com  Derek's Spark Gap Here is a 4-series adjustable gap I made for Derek, who wanted something suitable for neon transformers and potential transformers.  It uses 3/8" diameter tungsten. This gap occupies a space of only 6.75" x 3.5" x 2". (C) Jeff Behary, 2010