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  • Resolved

LM34: Erratic output on LM34

Prodigy 10 points
paul lester

Replies: 6

Views: 248

Part Number: LM34

We have been using a LM34 for the past 30 years as a temperature sensor in a device we manufacture. We have not had any issues until recently. The issue is that  1-2% of the sensors  will work fine then swing widely from low to high and they return to normal in most cases.  Has any seen this before or no of any issues with any batches of product? 

Prodigy 10 points
paul lester
  • Mastermind 22150 points
    Ren Schackmann
    Hi Paul,

    Our expert will get back to you on Monday CST.

    Thanks,
    Ren
  • Expert 3935 points
    Jalen Tate89

    Hi Paul,

    Can you provide more information on what you mean by swing widely from low to high, then return to normal? How are you measuring this output?

    Are you happening to drive a capacitive load LM34 output?

    Jalen

  • Prodigy 20 points
    paul Lunter

    In reply to Jalen Tate89:

    thank you for responding
    the temperature the sensor is sensing was 95 F but we are getting temp readouts of 20 - 200+ degrees changing a 2-3 times a minute. we change the sensor for another one and the system / circuit works fine. We reinstall the faulty sensor and sometimes they work fine other times it still reads incorrectly
  • Expert 3935 points
    Jalen Tate89

    In reply to paul Lunter:

    Hi Paul,

    Do you have a schematic you can provide on how you are implementing the part?

    Can you provide additional information on how you are measuring this output?

    I see you have tried reinstalling faulty sensor, have your tried a faulty sensor on a known good board? What is the result of this?

    Jalen
  • Expert 3935 points
    Jalen Tate89

    In reply to Jalen Tate89:

    Hi Paul,

    I haven’t heard back from you, I’m assuming you were able to resolve your issue. If not, just post a reply below (or create a new thread if the thread has locked due to time-out)

    Thanks,
    Jalen
  • Prodigy 20 points
    paul Lunter
    Thank you,
    My main question is about the component. Our system has not changed in 15+ years but we have seen some failures on the LM34. If no one knows anything going on the with the part I will keep looking into it from our end.
    Thank you
     
    Paul Lunter
    1- 727-536-5566 
    Plunter@HydroMassage.com Skype LunterP
     

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