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[help] home weather monitoring miniproject

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by alkoko111, Jun 29, 2009.

  1. alkoko111

    alkoko111 New Member

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    hello .. eric ! i want to ask about something

    About the temperature . someone implement the project like me with these values :

    Vref=1.28 v . applied on pin9 is 0.64 v
    LM358 works as buffer .

    he used these formulas :
    To get the minimum span that the adc can identify . min-span=Vref/255
    To get the Vin . Vin= Dout * min-span

    then :
    =1.28/255 = 5.01 mV

    He that this the min-span according the formula. and we know that the adc will give us 10 mV / centi but here will give us 5mv/centi ..... which mean we will take the output of the adc and divide it by 2 to get the tempr .

    example : if the output is 00000010= 2 in decimal then the program will read 2 and divide it by 2 to get the tempr ...... 2/2=1 c .

    is that make any sense ? i asked him about why you divided by 2 ? but he did not respond till now ?

    what do u think ?

    note : the program is working fine as this person illustrated .
     
  2. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    Hi,
    I would still advise to use the LM358 as an amplifier for the LM35 output also use the ADC's internal 5Vref.
     
  3. alkoko111

    alkoko111 New Member

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    okay .... i think this is convinced . thank you so much ...any new doubt i 'll DISCUSS it with you .
     
  4. dave

    Dave New Member

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  5. gnlds

    gnlds New Member

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    Hi, I have a thermometer project and I need help. I created a few circuits with different way. Although it seems correct, they didn't work. I added different versions of my project, please help me to solve this problem.

    Thank you !

    You can download .DSN files:
    http://rapidshare.com/files/392829295/Projects.rar.html
    Hotfile.com: One click file hosting: Projects.rar
     

    Attached Files:

    Last edited: May 29, 2010
  6. edeca

    edeca Active Member

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    It is best to start a new topic if you have a new question.
     

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