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Freezer alarm
This circuit uses an LTC1042 window comparator to form a freezer alarm. The 10M and 0.05uF combination sets the sample rate (of the LTC1042) of 1Hz, and the bridge values program the internal window comparator for the outputs shown. For normal freezer operation, pin 1 is high and pin 6 is low. Over-temperature reverses this state and can trigger an alarm. Current consumption is about 80 microamps. T is a Yellow Springs Instruments Company #44007 thermistor.