PID_temp_controller.jpg

From the MAKE Flickr Pool –
Member Boss Sauce shares pics of his precision temperature controller using a PID mechanism.

PID_diagram.jpg

A PID (proportional-integral-derivative) controller measures a specific variable (such as water temperature) in comparison to a predetermined setting (ideal temp). The controller then performs a corrective action via its control circuit in order to reach the desired setting (i.e. – increases power to the burner). Result = dinner cooked up just right.

PID temperature controller – Link

PID controller on Wikipedia – Link