Switching Using a PSU based on temperature

[phil21191]

Hi, im not particularly knowledgeable on electrical components but have some experience with soldering and programming PIC chips

I would like to switch a computer PSU on and off dependent on a temperature from a thermocouple say if it hits below 20c.

As you probably know computer power supplies can be turned on without being connected to a computer by joining the green pin with a black pin.

How would I go about this?

 

[Hero999]

Thermocouples are accurate but not simple to use. I'd recommend a simple thermistor.

You don't need a micro-controller, a simple comparator and relay will do.

http://www.silicontronics.com/index.php?action=ezportal;sa=page;p=17

 

[phil21191]

How controllable would temperature be? With this method I need to be able to shut off the psu at at temperature of around 27 so the Peltiers used dont cause condesation

 

[Hero999]

One of the resistors could be replaced with a potentiometer to adjust the temperature threshold.