I came across this info on coils, mainly to do with tesla/smith/kapanadze but it made for an interesting read.

http://free-energy-info.co.uk/Chapter5.pdf      Pages 41-107.

more of the same

http://www.free-energy-info.com/Utkin.htm

Thanks for sharing guys, interesting read as always with Tesla
Abstractly speaking it seems as though FE/OU devices has one thing in common, which is cold processes in the sense that when you get it working there's no heat disippated anywhere in the process.