From: utzoo!decvax!harpo!seismo!hao!hplabs!sri-unix!KING@KESTREL Newsgroups: net.physics Title: perpetual motion top Article-I.D.: sri-unix.4968 Posted: Wed Dec 29 11:49:48 1982 Received: Fri Dec 31 02:35:12 1982 From: Richard M. King I once looked at a battery powered clock that had a magnetized balance wheel, but instead of the usual escapement on the balance wheel there was a ratchet pawl that drove the gears of the timekeeping mechanism. The only coupling between the battery and the wheel was a set of coils near the wheel, connected to an electronics package, in turn connected to some device that was probably a hall-effect sensor. I suspect that's what you have there. A Lithium watch battery would cost the manufacturer about a quarter and would last for five or ten years. There could even be a small photovoltaic cell recharging the battery. Dick PS: By the way, has anyone heard any more about the alledged room-temperature superconductor? -------