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Hour Meter Circuits
Last Updated on:
Friday, April 25, 2008 05:10 PM |
| Circuits Designed by Dave Johnson, P.E. : |
- 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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| Machine
Vibration activates Hour Meter: 01/16/97 EDN-Design Ideas by David Johnson
Battery-powered digital hour meters commonly monitor how long a machine is in operation by detecting when the machine is supplied with power.
However, it is often difficult or dangerous to connect a battery-powered hour meter to a line-powered machine. When the machine being
monitored produces de-tectable vibrations, you can use the circuit in Figure 1, which doesn't require any power-line connections. The circuit
uses just one IC and allows you to turn a battery-powered hour meter on and off according to a machine's vibration. (added 09/05) |
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