How to Build a Freezer Alarm

How to build a freezer alarm. The freezer alarm alerts you when the freezer temperature lowers and can be assembled from about 15 simple electronic components for less than $20.



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The device requires two basic elements: a thermometer (which continuously monitors freezing compartment temperature) and a comparator circuit (which decides when the thermometer reading has gone too high).
PHOTO: MOTHER EARTH NEWS STAFF
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Diagram: Freezer alarm system.
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