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Circuits designed by David Johnson,
P.E.
Last Updated on:
Thursday, March 22, 2012 06:10 AM
Master Category List -
Dave's Circuits
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Vibration
Monitors Circuits
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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)
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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
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