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Project Notes

#595 LM35 Temperature Sensor

Reading ambient temperature with the LM35 and an Arduino without output display on a Nokia 5110 LCD.

Build

Notes

This circuit uses an LM35 Precision Centigrade Temperature Sensor to measure ambient temperature, and display the result on a Nokia 5110 comptible LCD.

The LM35 is part of a series of easy to use temperature sensors:

Sensor Output Voltage Linearity
LM34 proportional to temperature in Fahrenheit (ºF) 10mV/ºF
LM35 proportional to temperature in Celsius (ºC) 10mV/ºC
LM335 proportional to temperature in Kelvin (ºK) 10mV/ºK

Specifications for the LM35:

  • Directly calibrated in ̊Celsius (Centigrade)
  • 0.5̊C accuracy
  • Less than 60 μA current drain
  • Low impedance output, 0.1 Ω for 1 mA load
  • Rated for full −55̊ to +150 ̊C range

Construction

Breadboard

Schematic

Code

See LM35.ino for the sketch.

Reading temperature is straight-forward:

  • LM35 output voltage is read with analog input
  • scaled to 10mV/ºC

Libraries used:

  • u8glib library used for driving the LCD

Credits and References

About LEAP#595 SensorsLM35LCDArduino
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This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is my personal collection of electronics projects, usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting (IMHO!).

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Feel free to borrow liberally, and if you spot any issues do let me know. See the individual projects for credits where due. There are even now a few projects contributed by others - send your own over in a pull request if you would also like to add to this collection.