lm35 temperature sensor module for multimeter

| | , , , ,

Temperature x voltage converter with Lm35. To be used with a digital multimeter with a range from -50 °C to 150 °C. With a 9V battery and a home-built probe. And all this without any adjustments, thanks to the LM35!
Curiosity about degrees centigrade and Celsius.

Ice melts at 0 °C and the boiling point of water at sea level is 100 °C. Using these two reference points, the temperature scale is quickly calibrated. When we speak °C it is degrees Celsius and not centigrade as we can see in some literature, centigrade is a scale of 100. While temperature goes beyond 100. So, the correct is to speak degrees Celsius! Well enough blah blah…
Today, thanks to a specialized integrated circuit from National Semiconductor, called LM35, we don’t need any calibration to get the correct temperature.

Lm35 temperature sensor module for multimeter

Lm35 Temperature Sensor Module For Multimeter
Lm35 Temperature Sensor Module For Multimeter

For the circuit we need a 9v battery and a negative supply voltage. This is obtained according to the LM35 datasheet by 1n4148 diodes D1 and D2. Resistor R1 decouples the probe output from the high impedance output of the multimeter.
Resistors R2,R3(90K)/R4(10K) form a voltage divider so that 1 °C is equivalent to 1mV. So the reading on the multimeter display will be direct. Since the output of the Lm35 ⇒ 1 º = 10mV

The LM35 should be mounted in a metal tube of about 5 to 10 CM, connected to the main circuit by a three-wire cable no more than 1 m long. The tube should be hermetically sealed on both sides to allow the measurement of liquids.

Get new posts by email:
Follow us on social media

The main board and battery should be placed in a small plastic box. The board should be isolated from the battery to avoid short circuits and damage caused by the corrosive content of the battery.

The LM35 should be mounted in a metal tube of about 5 to 10 CM, connected to the main circuit by a three-wire cable no more than 1 m long. The tube should be hermetically sealed on both sides to allow the measurement of liquids.

Operating mode of the circuit with lm35 sensor:

Before making a temperature measurement test the battery by pressing S1, everything ok just connect the unit to the multimeter to make the measurements. Depending on the temperature, the multimeter on the scale Volt DC 200mV will indicate a voltage of -55mV to 150mV or the scale to be used depends on the multimeter, this voltage corresponds to the temperature of -55 to 150 °C. Or depending on the range of the Lm35 used!

PCB for lm35 temperature sensor module for multimeter

Lm35 Temperature Sensor Module For Multimeter Pcb
Lm35 Temperature Sensor Module For Multimeter Pcb
Lm35 Temperature Sensor Module For Multimeter Pcb
Lm35 Temperature Sensor Module For Multimeter Pcb

lm35 thermometer circuit components

PartComponentValueDescriptionAmount
Resistors 1/4W
1R115KResistor 5%1
2R268KResistor 1%1
3R322KResistor 1%1
4R410KResistor 1%1
Capacitors
5C1, C2, C3100nCeramic Capacitor3
Semiconductors
6IC1LM35 or Lm35APrecision Temperature Sensor1
7D1, D21N4148Diode2
Miscellaneous
8JP1, JP2Pin HeaderConnect 9 to 12V power supply1
9JP2Pin HeaderConnecting the probe tip1
Solder, Wires, Pci, Box, Source, Male banana jack

For more information about the lm35, download the PDF datasheet of the lm35 integrated
Download PDF, PNG and Gerber files for this project.
Download
Mirror

Datasheet PDF LM35

How useful was this post?

Click on a star to rate it!

Average rating / 5. Vote count:

No votes so far! Be the first to rate this post.

As you found this post useful...

Share on the social networks!

We are sorry that this post was not useful for you!

Let us improve this post!

Tell us how we can improve this post?

Previous

Circuit of graphic equalizer LA3607

LM3886 amplifier board gainclone LM3886TF PCB

Next

Leave a Comment