Wheatstone bridge temperature detection circuit

Wheatstone bridge temperature detection circuit

Place the thermistor directly in an appropriate position in the refrigerator
, and use the characteristic that when the thermistor is affected by a small temperature change in the box
(usually 1 to 2°C), its resistance value will
change accordingly. Work. This small temperature change
can be detected using a bridge temperature sensing circuit, shown in the figure
is a Wheatstone bridge temperature sensing circuit .
    The circuit is
composed of a bridge circuit, a voltage comparison amplifier and a relay. Connect the power supply to both terminals C and D. According to Kirchhoff 's
law, when the resistance value of the bridge is I×R4=R2 flow past. The thermistor value Ri changes with the change of the surrounding environment temperature. When the balance is destroyed, there is a current output between A and B. Therefore, when constructing a temperature controller, the temperature adjustment range and operating temperature can be easily changed by selecting an appropriate thermistor value.