Gadget Freak has a cool Freezer Failure Alarm project that is based on the PIC Microcontroller. Most projects have no important purpose but this one sure does. It could save you hundreds of dollars if you have a freezer full of meat! Looks like a nice simple yet effective design. See this document for full build details.
"The gadget is built around a small controller, an alarm and a temperature sensor. While temperature monitors are common, Grill’s device remembers temperature variance and displays the length of time the freezer rises above the set temp. The gadget is relatively small and costs less than a couple of steaks bought on sale and stored in the freezer."
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A place I worked at had such freezers all over the building for storing very expensive frozen adhesives tied into the buildings security system. Security would transfer items from a failed freezer to a standby if needed. It would take nothing more than a relay to tie that into a security system.
Thanks for the tip on the IC as it’s a winner. I may whip something up for the ATTINY when I get past this current project.