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DiscoverCircuits.com -- Hobby Corner
Last Updated on:
Tuesday, June 01, 2021 03:06 PM
Hobby Circuits List
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LINK to Dave's circuit, but DO NOT COPY any files to your WEB
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Alarm Circuits |
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UNPLUGGED
POWER CORD ALARM
designed
by David A. Johnson, P.E., 7/8/2000 |
Many medical devices, such a portable X-ray and ultrasound equipment, carry their
own batteries. However, the frantic pace of some hospital emergency rooms might
cause the device to be shoved off into a corner without being plugged back into an
AC power source to recharge their batteries. So, I designed
this circuit to emit an
audible alarm whenever the device’s power cord was unplugged from the wall for a
period of time. The device was designed
to snap onto the outside of a power cord,
where it senses the AC electric field emitted. No direct connection to the internal
wires of the power cord is needed. I also included a low battery voltage monitor. |
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Click on Circuit Below to view PDF of Schematic |
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