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• Home Made Geophone Detects Foot Stomp
  A home made geophone is made from a strong magnet, a coil of wire and a rubber band. The circuit is sensitive enough to detect the vibrations of a nearby foot stomp.  It could be used as an earthquake detector.  (added 7/06)

• Human Traffic Footstep Detector
  This circuit uses a surplus geophone to detect human footsteps from 100 feet away.  It was designed for monitoring the Mexico/USA border.  This preamp part of the system draws about 50 microamps from a 12 volt supply.  (added 12/04)

• Human Traffic Footstep Alarm
  This circuit processes the amplified signals from the footstep detector circuit and activates a microprocessor when the circuit detects footsteps.  At has an adjustable sensitivity.  (added 12/04)