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having a problem with LM35 temperature sensor

samiboutgoulla

Hello, I just started a project with LM35 (temperature sensors) with Arduino, after mounting it on my breadboard I noticed that the values ​​in the serial monitor are inconsistent and vary in a strange way, for example I get 21°, 20°, 22° 24° successively which is impossible I get the same result with 5 different sensors,  even whern i use a heat source the temperature the values vary also in a strange way and I don't know where the problem is can someone help me please? image imageimage

  • 0 in reply to samiboutgoulla

    Unless its very hot in your lab just holding the sensor with your fingers should warm it up a bit.

    The lighter could get a bit too hot.

    MK

  • 0 in reply to michaelkellett

    i'm from morocco , i notice a thing even when i'm approching heat source the temperature don't raise

  • 0 in reply to Robert Peter Oakes

    i even notice that tempreature wes decreasing when approching a heat source instead of increasing

  • 0

    The pins on these sensors are a bit thin to be sure of a good connection in a breadboard.

    One thing to try is just measure the sensor output voltage with a DVM as a heat source is applied.

    Measuring at the sensor will indicate if the sensor is connected properly and working.

    Measuring at the Arduino will indicate if the connections are good.

    If you have a scope, you might be able to see how much noise is on the signal.

  • 0

    There' also might be a good chance of something like this:

    https://youtu.be/NiNTDKKATmo?feature=shared

  • 0

     You can try one of the circuits below.  They are taken from the LM35 datasheet.  The capacitance of your breadboard may be impacting your readings.
    Still...  video is very compelling.
    image

  • 0

    I have been bitten by fake temperature sensors before as well...