Hour meter activated by magnetic influence

Abstract

An hour meter is activated by the stray magnetic flux leaking from a piece of equipment to be monitored or surrounding a conductor supplying current to operate that equipment. A tie down rod extends from the housing of the hour meter, and serves the dual function of providing a means to strap the hour meter onto the housing of the equipment and as an antenna to conduct alternating magnetic flux to a coil within the hour meter. There an alternating voltage is induced in the coil, which is rectified by a doubler circuit and applied to a switching transistor, which in turn allows a timer to run from a battery contained within the hour meter. The battery only supplies power to run the timer; the sensing circuit itself is self-powered by the energy induced by inductive coupling to the coil. A coupling adapter plugs into the wall, allows an appliance to be monitored to plug into it, while coils within the coupling adapter serve the dual purpose of supporting the hour meter by surrounding the ends of its tie down rod and coupling magnetic flux thereto, so as to activate the hour meter when the appliance is drawing current.