A simple thermostat device to keep the temperature constant. In the Electronic thermostat project, you can select the desired temperature value to control at 4 levels: 30, 40, 50, 60 degrees. It can also be modified and sensitive to control a wide temperature range between -50 ºC and +125 ºC by changing the value of the appropriate resistances in the circuit.
Since it has high sensitivity and lower tolerance value than the bimetal type, 10K NTC thermistor was used in this project.
Thermostat Circuit Diagram
Electronic Thermostat Working Principle
LM339 comparator integrated circuit receives the voltage signal that changes with temperature. Then it compares the voltage value coming from NTC thermistor. Selectable resistance is determined as reference value with voltage divider.
Reference voltage setting (V ref) is the temperature cut-off point setting. The result of the voltage comparison made by LM339 is sent to BC337’s base to drive the relay and the relay operates.
