This is a small and Simple Digital Thermometer Circuit with IC LM35, it uses LM35 sensor IC and also the circuit show temperature in voltmeter.
Moreover, it is cheap and very easy to make and is also good for students and DIY beginners.
Circuit Working:
Parts List:
| Components | Values | 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 and this LM35 is IC temperature sensor, which gives output in millivolt according to temperature.
Then the sensor give 10mV for every 1°C rise in temperature, for example if room is 30°C then sensor output is 300mV.
After that, the voltmeter will show this voltage and we can read temperature from it.
Furthermore, in this circuit, pin 1 of the LM35 receives the supply voltage from the +9V battery.
Pin 2 provides the output signal and connects to the meter through a 10k resistor and a 2k preset for calibration.
Pin 3 connects to the battery’s negative terminal and serves as the ground pin.
Finally, 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 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.
- Next, pin 1 of LM35 (+Vs) connect to +9V battery positive.
- After that, pin 2 of LM35 (Vout) is output and connect it to voltmeter positive through resistor R1 and variable resistor VR1.
- Now connect voltmeter ground pin to circuit ground.
- Then pin 3 of LM35 (Gnd) connect to battery negative.
Conclusion:
Overall, this Simple Digital Thermometer Circuit with IC LM35 is cheap and easy and it needs no microcontroller and no coding.
This project uses only an LM35 sensor, a resistor, a voltmeter and a 9V battery.
We can use it to measure room temperature or perform small experiments and therefore, this project is ideal for beginner DIY learners.