This is a universal thermostat, which can be used to switch. Used 220 V The author uses the circuit as a breeding thermostat. 220 V Thermostats Circuit Diagram : The circuit is built around an opamp 741, which is the voltage of the voltage divider R1/R2/R3 compares with the reference voltage of R4/R5/P1. As the temperature rises, the resistance of the NTC fall's, causing the voltage drops to the positive input of the opamp. At some point the folded opamp to spert and the transistor T1 and the load is switched off. The turning point (or the shutdown temperature) is set to P1. Parts List: R1 = 6.8 kΩ R2, R3 = 1 kΩ NTC R4 = 12 kΩ R5 = 3.9 kΩ R6 = 820 Ω R7 = 27 kΩ R8 = 470 Ω R9 = 100 Ω P1 = 10 kΩ C1 = 470 μF C2 = 100 V nF/250 D1 = LED D2 - D5 = 1N4148 Of T1 = BC548 2N1613 T2 = TIC206M IC1 = 741 IC2 = K3020P