Non contact current sensor

Discussion in 'The Projects Forum' started by abadi, Feb 16, 2010.

  1. abadi

    Thread Starter New Member

    Nov 8, 2009
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    hiii guys

    i really need a help in my FYP , and its about non contact current sensor which is " Rrogowski Coil "

    just to make it short
    i have already design the coil and also the amplifier
    the coil already work for high frequency ( 1 M ) and the result is 24mV, but my project is about low frequency between ( 1 f - 1k f )

    so, i design the amplifier

    which is non-invierter and my ( Rf = 100 K ohms , Ri = 1 K ohms )
    so, my Gain is ( G = 100 )

    when i pass 1M frequency through the coil and i connect the coil to my op-amp


    but i dont get any result


    could any 1 help me on that ?????????
    why there is no result even the Gain is 100
     
  2. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Can you post the circuit?
    What opamp / amplifier do you use?

    Greetings,
    Bertus
     
  3. abadi

    Thread Starter New Member

    Nov 8, 2009
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  4. abadi

    Thread Starter New Member

    Nov 8, 2009
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    did you get it ????
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    What values did you use for R1 and R2?
    If R1=101 Ohms and R2 = 10k Ohms, you will get a gain of approximately 100.

    Post the design details of your Rogowski coil.
     
    Last edited: Feb 16, 2010
  6. abadi

    Thread Starter New Member

    Nov 8, 2009
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  7. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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  8. abadi

    Thread Starter New Member

    Nov 8, 2009
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    Thanx bro
    i will try to do it tomorrow and see how its gonna work
     
  9. t06afre

    AAC Fanatic!

    May 11, 2009
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  10. abadi

    Thread Starter New Member

    Nov 8, 2009
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    so, what i have to do ????
    i have to increase it or decrease the gain ????
     
  11. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    You will need an opamp with a higher gain product ( > 100 MHz ).
    I have attached a list of high speed opamps (remove the .txt and load it into excell).

    Greetings,
    Bertus
     
  12. t06afre

    AAC Fanatic!

    May 11, 2009
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    Yes you must a faster OPAMP. Why did you select the LT1014 in the first place? Also perhaps split up the gain stage. Instead of 1 stage with gain equal to 100 try two stages with gain equal to 10.
     
  13. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    Did you read the article by Cappels here: http://www.cappels.org/dproj/aciprobe/ACCurrentProbe.html

    He describes what you need to do to get low frequencies.

    What do your calculations (see Cappels) show? Can you describe your coil to us in more detail? What actual frequencies have you tried?

    John
     
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