LM35 connected to op-amp

Discussion in 'Homework Help' started by aab09, Dec 22, 2014.

  1. aab09

    Thread Starter New Member

    Dec 12, 2014
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    Hi
    I need your help. My project is to design sensor that connected to op-amp.
    temperature range from 35°C – 45°C, and ADC range 0 – 3.3V.
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    So what have you already done?
     
  3. aab09

    Thread Starter New Member

    Dec 12, 2014
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    actually, nothing
    I need some hints to begin designing
     
  4. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Well, I would start by reading the data sheet for the LM35
     
  5. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    The sensor gives out 10mV per degC, 35C to 45C thats a voltage output of 350mV to 450mV,
     
  6. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    .... so you need to amplify and offset those mV to get 0-3.3V (ideally). Read up on opamp theory.
     
  7. aab09

    Thread Starter New Member

    Dec 12, 2014
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    I asked the doctor about it he tell me to get output voltage of opamp=0 when T=35, output voltage of opamp=3.3 when T=45
     
  8. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    We, instead just giving you the answer, in which case you learn nothing, are waiting for you to show some initiative and suggest a solution...

    btw- I am a retired doctor (PhD). If you were my student, I would fail you if I learned that you just copied a solution that someone handed to you.
     
    Last edited: Dec 22, 2014
  9. ScottWang

    Moderator

    Aug 23, 2012
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    So now you should figure out how a op amp to do the amplifying as inverting and non-inverting, and then draw the circuit and attach it here.
     
  10. Wendy

    Moderator

    Mar 24, 2008
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    You will note that everyone assumes this is home work, which means it gets treated differently. Make a serious attempt to solve the problem, draw a schematic you think might work, and you will go further. The more input you give the more hints toward solutions you will get, and the more you will learn.
     
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