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Circuits designed by David Johnson,
P.E.
Last Updated on:
Saturday, December 23, 2017 02:27 PM
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Alarm Circuits |
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UNPLUGGED POWER CORD ALARM |
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 Drawing Below to view PDF version of Schematic |
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