electromagnetic field sensor

Discussion in 'General Electronics Chat' started by phill, May 9, 2009.

  1. phill

    Thread Starter New Member

    May 9, 2009
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    for a college project, i need to design and build a "car" which will follow an electromagnetic field eminating from a wire. The wire will be supplied with 20kHz, can any body suggest a suitible sensor to detect this field, at the moment i'm thinking some coils of wire!

    thanks
     
  2. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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  3. mik3

    Senior Member

    Feb 4, 2008
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    Coils work very well for this case. I have personal experience because my team at my university built one of this with inductive guidance.

    Have a look at my blog to see it.
     
  4. phill

    Thread Starter New Member

    May 9, 2009
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    the video looks very impressive! did you use any formulea to calculate the corect size/values for the coils? Im planning to feed the sensor signal in to an ADC of a micro. What sort of conditioning did you have to do? i'm not after specifics, just generalaties to point me in the right dirrection.

    Thanks!
     
  5. mik3

    Senior Member

    Feb 4, 2008
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    They told us to use a 330uH coil but the the current's frequency was 10 kHz. It should work with 20 kHz too.

    I suggest you to use an amplifier to amplify the inductors signal and then feed it into a band pass filter as to pass only the 20 kHz signal and reject noise. Also, use a pot on the amplifier as to be able to adjust its gain, it really helps.
     
  6. phill

    Thread Starter New Member

    May 9, 2009
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    cool, that will help no end! i'll let you know how it go's!
     
  7. mik3

    Senior Member

    Feb 4, 2008
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    What is more, I recommend you using more than two sensors as to be able to detect when the car losses the track easily. I used two sensors and I had to sacrifice between steering accuracy and lost track detection. Finally, I didn't use lost track detection and achieved a very accurate steering.
     
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