A patent for a similar device from back in the 60s: http://www.google.com/patents/US3115194 http://www.google.com/patents/US3115194 Happened to see it while ar

A patent for a similar device from back in the 60s: http://www.google.com/patents/US3115194 http://www.google.com/patents/US3115194 Happened to see it while archiving the inventor's papers. :)