The Turn Of The Century Electrotherapy Museum http://www.electrotherapymuseum.com Tesla's Table Top Coils... A few color renderings from blueprints and articles... Excerpts from Leland I. Anderson's Nikola Tesla:  Lecture Before The New York Academy Of Sciences - April 6, 1897 Twenty First Century Books Larger photo Blueprint of H.G. Fischer "H" Tesla Coil - 3600 turns of wire in the secondaries totals. This bipolar Tesla Coil uses a 1000V transformer and .6 mfd mica condenser. It uses only a single 1/4" tungsten spark gap. Of the hundreds of antique Tesla Coils I have experimented with, this is the most efficient I have ever seen, and I believe its design is close to what Tesla himself was building in the 1890s. Top view of coils under the case Side view of coils - posts are 7" between centres Crackling sparks: To show the unusual nature of this coil, the unit was powered by only 20 volts AC.  The output on the power transformer - normally 1000 volts - was less than 200 volts.  A barely visible spark gap was maintained less than .001".  Sparks 4" long, seen above, crackled between the terminals. At full power, consuming 15 amps, this unit produces nothing short of a flame! McIntosh Bipolar Tesla Coil The coarse tapped winding seen on top of the kicking coil is used for the cautery circuit. 3 - 4" Sparks.  This unit operates at a higher frequency than the Fischer X-Ray. An efficient 3" spark Tesla coil. A selection of Tesla Coil cross-sections... (C) Jeff Behary, 2008