These days electronic room thermometer is very popular, though it is expensive. Now here we designed a simple and cheap electronic room thermometer using temperature sensor and op-amp 741.
Circuit Description of Electronic Room Thermometer using Op-amp 741
The heart of the circuit electronic room thermometer is IC1 (LM3911), where is used here as temperature sensor. Output of this IC is variable according to temperature change. It’s output increase at the rate of 10mV/0C rise in temperature. At 00C its output is 2.73V.
The output from IC1 is given to input of IC2 (Op-amp) for necessary amplification. Amplified output from in 6 is given to micrometer through potentiometer VR2. The sensitivity of electronic room thermometer is ± 0.10C. The range of this thermometer can be adjusted by VR1.
PARTS LIST OF ELECTRONIC ROOM THERMOMETER
Resistor (all ¼-watt, ± 5% Carbon)
R1 = 33 KΩ
R2 = 330 KΩ
R3 = 3.3 KΩ
VR1 = 100 KΩ
VR2 = 2.5 KΩ
IC1 = LM3911
IC2 = µA741
M1 = Micrometer