Twin coil help?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" <Beans45601-at-aol-dot-com>

I have been interested in building a twin coil system for a while now, but 
I can't seem to find a good (keyword, good) website explaining what is 
different for building a twin system instead of just one coil. I know they 
have different primaries that are 180 degrees out of tune from each other 
(not sure if I worded that right) and they have different secondaries. But, 
say that you were using a 12/120 NST to power them, what size cap would you 
need? Would it be the same for a regular coil?
Thanks
Adam