Original poster: "Darin Willson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <darinwil-at-execpc-dot-com> Are there any equations for a DC Coil. I saw Kevins Specs for his but no equations. Also the AC frequency plays a big part in an AC coil. Is the firing rate of the spark gap in a DC coil similar? Thanks, Darin