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MACHINE VIBRATION
TRIGGERS HOUR METER This circuit allows an off-the-shelf
battery powered digital hour meter to be turned on and off, according to a machine's
operation, without requiring a direct electrical connection to the machine. Machine
vibrations are detected by an off-the-shelf piezoelectric wafer. The wafer is normally
used as a sound generator. The 3v power could be tapped from the hour meter's own lithium
battery or from a separate 3v lithium battery. The circuit only draws about 1.5uA, so a
250mA-hr battery would power the circuit for about 10 years. Published in EDN, Jan 16, 1997
Click on Drawing Below
to view PDF version of Schematic
