4-20 ma analoge current generator

Discussion in 'General Electronics Chat' started by plcboy, Apr 2, 2013.

  1. plcboy

    Thread Starter New Member

    Apr 2, 2013
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    HI
    This is my first post and I hope somebody is able to help me.
    I want to build a 4-20 ma analoge signal generator for test purposes, any DIY kit, website, schematics.
    Thanks a lot
     
  2. crutschow

    Expert

    Mar 14, 2008
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    What controls this signal generator?
     
  3. plcboy

    Thread Starter New Member

    Apr 2, 2013
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    HI
    This is not used to control but to test a simple ac motor drive or similiar applications. Thanks
     
  4. crutschow

    Expert

    Mar 14, 2008
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    3,229
    Below is a relatively simple 2-20mA current source that will drive a grounded load. The transconductance is 1mA/0.1V (0.1mA output current increase for 0.1V input voltage increase). The op amp can be any standard rail-rail type op amp. The P-MOSFET can be virtually any device that has >=100mA and >=20V rating.

    The circuit is relatively insensitive to small changes in supply voltage.

    If you want to be able to adjust the output for exactly 2mA output with 0V input, you can replace R2 and R4 with a 20kΩ pot. That will also allow adjustment of the 2mA point for other supply voltages.

    If you want to simulate the circuit with LTspice I can post the simulation file.

    20mA Current Source.gif
     
  5. plcboy

    Thread Starter New Member

    Apr 2, 2013
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    Thanks for the reply. I have seen some notes about IC XTR 110.
     
  6. crutschow

    Expert

    Mar 14, 2008
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    Looks like that may be a simple way to do what you want.
     
  7. plcboy

    Thread Starter New Member

    Apr 2, 2013
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    Thank you CRUTSCHOW for the reply. Any details on IC XTR110 except datasheet. Thank you
     
  8. atferrari

    AAC Fanatic!

    Jan 6, 2004
    2,648
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    Look for Burr Brown's application notes. IIRC there are application notes for their 4-20mA loop related chips, yours included.

    If have time I could look in my library.

    /Edit

    I had time and my library is just 2 m away from here... :eek:

    There are two application bulletins in their Applications Handbook - 1994

    AB-043
    AB-165

    Edit/
     
    Last edited: Apr 3, 2013
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