Frost Alarm


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 Alarm
Click here to download the full size of the above Circuit.

ature is near the switching threshold of this circuit.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

LM317 Regulator Circuit
3-Way Light Control
Isolated 15V To 2500V Supply
eminent
Led display digital Voltmeter
Mini GSM localizer without GPS
80M CW QRP rig
Keypad-Operated Switch No.2



Top