This is a small and Simple Digital Thermometer Circuit with IC LM35.
It uses LM35 sensor IC.
The circuit show temperature in voltmeter.
It is cheap and very easy to make.
Good for students and DIY beginners.
Circuit Working:
Parts List:
| Component | Value | Quantity |
|---|---|---|
| Resistors | 10k | 1 |
| Preset 2k | 1 | |
| Semiconductors | Voltmeter 200mV | 1 |
| IC LM35 Temperature Sensor | 1 | |
| Battery 9V DC | 1 |
The heart of circuit is LM35 sensor.
LM35 is IC temperature sensor.
It gives output in millivolt according to temperature.
The sensor give 10mV for every 1°C rise in temperature.
For example if room is 30°C then sensor output is 300mV.
The voltmeter will show this voltage and we can read temperature from it.
In circuit, LM35 pin 1 is supply pin, connected to +9V battery.
Pin 2 is output pin connected to meter with help of 10k resistor and 2k preset for calibration.
Pin 3 is ground pin connected to negative of battery.
The meter shows voltage in mV which is directly equal to temperature in °C after calibration.
Formula:
Formula for LM35 thermometer is very simple.
Output voltage = 10mV × Temperature in °C.
here,
- Output voltage is the voltage coming out from LM35 sensor pin 2.
- 10mV is constant value given by LM35 as it gives 10 millivolt for every 1°C.
- Temperature in °C is the real temperature around sensor in degree Celsius.
How to Build:
To build a Simple Digital Thermometer Circuit with IC LM35 following are the steps we need to follow:
- First collect all parts as in circuit diagram.
- Pin 1 of LM35 (+Vs) connect to +9V battery positive.
- Pin 2 of LM35 (Vout) is output and connect it to voltmeter positive through resistor R1 and variable resistor VR1.
- Connect voltmeter ground pin to circuit ground.
- Pin 3 of LM35 (Gnd) connect to battery negative.
Conclusion:
This Simple Digital Thermometer Circuit with IC LM35 is cheap and easy.
It needs no microcontroller and no coding.
Only LM35, resistor, voltmeter and 9V battery are used.
It can measure room temperature or small experiments.
This project is good for beginner DIY learners.