검색어 : 구글 -> Temperature control circuit

Circuit explanation of the temperature controller
http://www.interq.or.jp/japan/se-inoue/e_acryl23.htm

Feedback and Temperature Control
http://newton.ex.ac.uk/teaching/CDHW/Feedback/DIY-PID.html

temperature control circuit
http://www.shortcircuit.com.au/EVCA/tcc.htm

temperature controller
http://www.omega.com/prodinfo/temperaturecontrollers.html