Electronic climate controller / Rizal Mat Jusoh and Hasrul Zaidi Zainol Abidin

Fundamental of Electronic climate controller (ECC) is temperature sensor. This temperature sensor has a temperature coefficient of reverse breakdown voltage equal to + 10 mV /°K , is extrapolated to O mV at 0°K . Thus, at room temperature (298.2(K), the voltage across IC4 (LM 335) should be 298.2 mV X 10 mV /°K = 2.982V. But, in practice it has some error due to self-heating and other related factors (heat sources). These errors are eliminated during the calibration procedure at last activity of construction. The dot/bar display driver IC2 (LM 3914) will drive 10 LEDs to show room temperature, where each of it is marked with certain temperature. Example, LED 1= 67(F and LED 2 = 69(F, if room temperature is 69(F both LEDs will ON. Whenever room temperature reach certain value Relay (RY 1) will switch ON fan or air-condition. The fan will OFF automatically when room temperature is equal with settled temperature on calibration procedure.