current sensing resist ?

Discussion in 'General Electronics Chat' started by Dr.killjoy, Dec 5, 2013.

  1. Dr.killjoy

    Thread Starter Well-Known Member

    Apr 28, 2013
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    I read that I can hook up a current sensing resitor up to a op amp in order to limit the amount of current flowing through the fet in my constant current load project? ??? Is this correct????







    Thanks
    Jason SR
     
  2. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    As long as I = E / R is a limit you can live with that sounds fine to me.
     
  3. bance

    Member

    Aug 11, 2012
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    A current sensing resistor or shunt is usually used as a convenient way for converting voltage to current for measurement purposes. If, for instance, you select the value of the shunt to be 1 Ohm, then from Ohm's law:-

    I = V/R
    I = V/1 or I = V

    So by measuring the voltage across the shunt, you have instantly deduced the current, since they are the same!

    HTH Steve.
     
  4. t06afre

    AAC Fanatic!

    May 11, 2009
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  5. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    What circuit are you using to control the current?
     
  6. bance

    Member

    Aug 11, 2012
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    This is the OP's project thread, Post #8 has a schematic.
     
  7. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Like this:
     
  8. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    You can make your own precision shunt using constantan or manganin wire, which has zero TC and is available in various thicknesses.
     
  9. Dr.killjoy

    Thread Starter Well-Known Member

    Apr 28, 2013
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    Thanks guy for the help and info but I have decided to go a different route..
    My design for the constant current load is almost done and I am very proud of it and will update the thread later info...




    Thanks
    Jason SR
     
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