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Sensor Forum having a problem with LM35 temperature sensor
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Forum Thread Details
  • State Not Answered
  • Replies 39 replies
  • Subscribers 336 subscribers
  • Views 1734 views
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  • sensors
  • arduino ide
  • temperature sensor
  • arduino
  • analog
Related

having a problem with LM35 temperature sensor

samiboutgoulla
samiboutgoulla 2 months ago

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

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  • michaelkellett
    michaelkellett 2 months ago in reply to samiboutgoulla +3
    It looks as if you have no resistor from the output to a negative bias voltage - this means that you will get poor results as the temperature drops towards zero but you can ignore that for now. The sensor…
  • kmikemoo
    kmikemoo 2 months ago +3
    samiboutgoulla 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... shabaz's video is very compelling…
  • michaelkellett
    michaelkellett 2 months ago in reply to JWx +1
    Good idea but I think he has an external noise problem - let's wait and see ! MK
  • samiboutgoulla
    0 samiboutgoulla 2 months ago in reply to michaelkellett

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

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  • michaelkellett
    0 michaelkellett 2 months ago in reply to samiboutgoulla

    Do you have any way of measuring voltage  ?

    MK

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  • Jan Cumps
    0 Jan Cumps 2 months ago in reply to samiboutgoulla

    GND and 5V mixed at the Arduino?

    image

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  • samiboutgoulla
    0 samiboutgoulla 2 months ago in reply to michaelkellett

    i'm searching for a voltemetre , another thing i approched a lighter to lm35 the tempreature start decreasing

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  • samiboutgoulla
    0 samiboutgoulla 2 months ago in reply to Jan Cumps

    no i verfied there no problem with connections

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  • samiboutgoulla
    0 samiboutgoulla 2 months ago in reply to JWx

    i noticed a thing temperature start decreasing instead on increasing when approching a source of heat

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  • samiboutgoulla
    0 samiboutgoulla 2 months ago in reply to JWx

    another thing i approched a lighter to lm35 the tempreature start decreasing , i repeated it many times and the temperature is decreasing for sure 

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  • Jan Cumps
    0 Jan Cumps 2 months ago in reply to samiboutgoulla

    It helps, for photos, if you use black for ground and red for +5V. You 'll confuse the people that try to help, and yourself eventually.

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  • Robert Peter Oakes
    0 Robert Peter Oakes 2 months ago in reply to samiboutgoulla

    just a thought, have you checked the jumper cables are good, they look like banggood/alliexpress/amazon cheapies brand and I have had very poor results myself with them to the point were i will check every one with a dmm to be sure they are at or near 0 Ohms, I have found a very high percentage to be hundreds of ohms or more because of bad manufacturing and has caused me all sorts of problems in the past. get three wires strip the ends and use that instead just to test if you dont have a way to check them

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  • Robert Peter Oakes
    0 Robert Peter Oakes 2 months ago in reply to Robert Peter Oakes

    even ones with dupont connectors have had rust or really bad crimps too, not just those molded ones.

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