Frost AlarmCircuit Project

Posted on Feb 4, 2014

The thermistor used has a resistance of 15k at 25 degrees and 45k at 0 degrees celsius. A suitable bead type thermistor is found in the Maplin catalogue. The 100k pot allows this circuit to trigger over a wide range of temperatures. A slight amount of hysteresis is provided by inclusion of the 270k resistor. This prevents relay chatter when temper

Frost AlarmCircuit Project
Click here to download the full size of the above Circuit.

ature is near the switching threshold of this circuit.

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