Which is more stable as a constant current source FET or Op-amp?

Discussion in 'The Projects Forum' started by nilesh.thakare, Sep 2, 2010.

  1. nilesh.thakare

    Thread Starter New Member

    Sep 2, 2010
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    hi,
    i am confused in selecting constant current source using FET or Op-amp.I just want to know that which would be more stable,because i am using that current source for excitation of the RTD sensor.Please help.
     
  2. thingmaker3

    Retired Moderator

    May 16, 2005
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    I suggest a linear regulator might be more stable than either, as well as easier to impliment.
     
  3. t_n_k

    AAC Fanatic!

    Mar 6, 2009
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    Or even one of the 3 terminal adjustable current sources such as the LM334. If the adjustable current range meets your requirements.
     
  4. DickCappels

    Moderator

    Aug 21, 2008
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    A well-designed op-amp current souce will be much more stabl than an FET connected as a constant current diode.
     
  5. Papabravo

    Expert

    Feb 24, 2006
    10,179
    1,800
    It depends on the lengths you are willing to go to. There are many things that affect stability of a circuit. After you eliminate the big influences you can go after the smaller ones. There is a point of diminishing returns where you expend enormous resources for minuscule improvements.
     
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