A coupla years ago (before 9/11 I believe) Popular Mechanics had an article on EMP weapons. They even included diagrams and theory of operation for a non-nuclear device that could be made from common CATV supplies like PVC pipe and ground wire. I was gonna help the kids build one for the science fair but the wife said NO.
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This is CABL.com posting #150978. Tiny Link: cabl.co/mNri