Original poster: "claude masetto" <claudmas-at-optusnet-dot-com.au> Hello everybody, A couple of weeks ago there was a posting on the list by somebody who made a ballast and was using it series with 4 MOTS. I think the core was made from welding rods. I'm trying to track down this design information as I believe it works well, so if anybody can help it would be much appreciated. Thanks Claude.