20v dc convert to a ajustable 4 to 20 ma signal

Discussion in 'The Projects Forum' started by collin shrewsb, Nov 11, 2008.

  1. collin shrewsb

    Thread Starter New Member

    Nov 10, 2008
    4
    0
    Hi, i need to convert a 20v dc + to a 4 t0 20 mA variable signal
    can you help please
    thank you
    Collin
     
  2. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    230
    Collin,

    How do you want to vary the 4-20mA level? Are you trying to create a 4-20mA output transducer? Or, is this to be a test signal to check a 4-20mA receiving device?

    Ken
     
  3. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    Do you want to convert 0-20VCD to 4-20ma? I just came up with the reverse circuit, a 4-20ma to 0-5VDC for another thread.
     
  4. collin shrewsb

    Thread Starter New Member

    Nov 10, 2008
    4
    0
    Hi bill. the project is to test controllers on the air compressors as a simulator. the origenal layout is a 20v dc + (one wire) running to an air
    pressure transducer. this converts to a 0 to 20 mA signal. (one wire return) the idea is to simulate the air transducers. i want to use the 20v + from the controller and vary the 4 to 20 mA signal ( if possible). the controller converts the 4 to 20 mA signal to airpressure reading.as a result i can test the controllers alarm and cut out settings.
     
  5. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    Here is an adjustable constant current source, along with a DVM, should serve your purpose.

    Ken
     
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