millivolts to milliampere converter

Discussion in 'General Electronics Chat' started by DRSP, Nov 29, 2011.

  1. DRSP

    Thread Starter New Member

    Nov 29, 2011
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    Hello I'm new at this forum.
    In my project I use 2 different types of sensors.
    Sensor one gives a signal between 0 and 60 mV
    Sensor two gives a signal between 0 and 100 mV

    I need to build a conveter to convert the 0-60 mV to a 4-20 mA signal
    and a converter to convert 0-100 mV to a 4-20 mA signal.

    Does anybody know the answer?
     
  2. Adjuster

    Well-Known Member

    Dec 26, 2010
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    What is your load device? What is its impedance, or alternatively, how much voltage will it require? What bandwidth is needed? Is it acceptable to have a monitoring resistance in the common return?

    Answers to these questions, any other details you may be aware of, and perhaps a schematic of your expected arrangement will help people to comment on this.
     
  3. DRSP

    Thread Starter New Member

    Nov 29, 2011
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    0
    My device load is a PLC (25 ohms)
    It will require 24V DC

    it is acceptable to have a monitoring resistance in the common return!

    The sensor is actually the same as a bridge of 4 resistors
    [​IMG]
    Uploaded with ImageShack.us
     
  4. Adjuster

    Well-Known Member

    Dec 26, 2010
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    Perhaps this sort of structure?
     
  5. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    In a 4-20 mA signaling system you are free to put a sense resistor anywhere you wish. The system assumes you have 3 elements: a signal source, a signal receiver, and a power supply. Note sometimes these may be combined.

    One sticky point comes about if both of your sensors are electrically common. Then you probably want to isolate one so it can run in it's own current loop.
     
  6. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
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    TI XTR101 Though not cheap.

    Is this for an industrial application where accuracy is of utmost importance? If so, that is "The Standard" IC for the use you are looking at.
     
  7. DRSP

    Thread Starter New Member

    Nov 29, 2011
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    This is for an industrial application where accuracy is of utmost importance!

    Can I use the AD693 instead of the XTR101?
    And do you have a compete schematic for this solution?

    Thanks!
     
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