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Old 06-11-2013, 01:24 PM   #163 (permalink)
gone-ot
...beats walking...
 
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Don't even need a thermocouple, just use a cheap temperature-sensitive resistor with a suitably-sized current limiting resistor in series, and apply a known 'reference' voltage (5Vdc regulator?) across them to make a temp-sensitive voltage divider.

HOT temp will pull the voltage UP to some "threshhold" and COLD temp will pull the voltage DOWN to a lower "threshhold", and a digital comparator IC could "trigger" at those upper & lower voltages, providing control to drive bigger transistors to power the louver motor to open and close.
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