4 to 20 ma signal DAQ question


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  1. #1
    Join Date
    Apr 2007
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    Default 4 to 20 ma signal DAQ question

    This might be a total noob question but I would like to know how you measure current with the pic. I can see several adc ic's and options that measure voltage but not current. I am starting a data logging project and the source signal is 4 to 20 ma.(Miltronics Water level meter) The difference in voltage at that small current change seems too small to measure? Can I use the ADC on the pic or do I need a special IC current to voltage converter. I have also seen some solutions with an op amp but would prefer an all in one IC.
    Thanks
    Snap
    Beer is proof that God loves us and wants us to be happy.

  2. #2
    Join Date
    Nov 2003
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    Default

    A resistor is all you should need to convert the signal to a 1 to 5 volt range. A couple of links to look at.

    http://www.teicontrols.com/4-20.html

    http://www.allaboutcircuits.com/vol_1/chpt_9/3.html
    Dave
    Always wear safety glasses while programming.

  3. #3
    Join Date
    Apr 2007
    Location
    Southern Ontario
    Posts
    50

    Smile Thank you

    I am new to this electronics stuff (microbiology-chem background), but I am a fast learner and can not get over the fast and accurate responce I recieve in the forum. I try to help out in threads that deal directly with problems I have had and hope to one day help people in the same way I have been helped. I knew a voltage divider would some how be involved but I was unsure of the ohm's. I researched every way I knew how and still could not find the links you provided. By the way I can't get the spell checker to work in this forum and am lost whith out it.
    Snap
    Beer is proof that God loves us and wants us to be happy.

  4. #4
    Join Date
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    Wellton, U.S.A.
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    Default

    Spelll checker? What it that

    Use Fire Fox.
    Dave
    Always wear safety glasses while programming.

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