Thermostat

This is simple electronic thermostat using IC LM56.by using this one you can know whether the temperature of the equipment that you use is over heating or not.so this is very useful equipment to save your electrical equipments from over heating.





Two stable temperature trip points (VT1 and VT2) are created by dividing the LM56’s 1.250V internal voltage reference using 3 external resistors (R1, R2 and R3). There are two digital outputs for LM56 .Output1 becomes LOW when the temperature increases above T1 and goes HIGH when the temperature decreases below (T1±Hysteresis Temperature). In the same way, Output2 becomes LOW when the temperature goes above T2 and goes HIGH when the temperature goes below (T2±Hysteresis Temperature).


VT1 = 1.250V x (R1)/ (R1 + R2 + R3)
VT2 = 1.250V x (R1 + R2)/ (R1 + R2 + R3)
where:
(R1 + R2 + R3) = 27 k Ohms and
VT1 or T2 = [6.20 mV/degree Celsius x T] = 395 mV therefore:
R1 = VT1/ (1.25V) x 27 k Ohms
R2 = (VT2/ (1.25V) x 27 k Ohms) – R1
R3 = 27 k Ohms – R1 – R2