Electronic component to detect magnetism and reverse current

Discussion in 'General Electronics Chat' started by Mr. Arkham, Apr 24, 2009.

  1. Mr. Arkham

    Thread Starter New Member

    Apr 24, 2009
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    Hello everyone, and thanks for having such a nice forum.

    I did a search for what I think is the answer to my question; Hall sensors--but I'm not sure though. Please forgive me ignorance.

    What I'm attempting to do is have some sort of sensor that will detect a magnetic field and reverse the current of an electromagnet. The current will remain the same until the sensor detects another magnetic field and then switch again.

    Is this even possible? If so, can it do so several hundred or thousand times a minute?

    Thanks in advance..

    Mr. Arkham
     
  2. hgmjr

    Moderator

    Jan 28, 2005
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    Try searching on the keyword phrase "hall-effect" sensor?

    hgmjr
     
  3. Mr. Arkham

    Thread Starter New Member

    Apr 24, 2009
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    Thanks, will do. I guess that was what I was needing after all then, eh?
     
  4. hgmjr

    Moderator

    Jan 28, 2005
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    The use of a hall-effect sensor together with a bit of logic circuitry should meet the performance requirements you are seeking.

    hgmjr
     
  5. Mr. Arkham

    Thread Starter New Member

    Apr 24, 2009
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    Thanks for pointing me in the right direction. Now, I wish I had taken more electronic courses instead of just intro to digital circuits!

    I hate to ask, but where might I start looking in regards to the logic circuitry you mentioned? I had thought that a Hall sensor tied into some sort of commutator would do the trick; but engineering that with my limited knowledge seems daunting..if it would even work at all.

    Thanks again!
     
  6. hgmjr

    Moderator

    Jan 28, 2005
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    I would imagine the circuit would consist of the Hall-Effect sensor that feeds a D-type flip/flop. The output of the flip/flop would then feed an h-bridge driver connected to the electro-magnetic.

    hgmjr
     
  7. Mr. Arkham

    Thread Starter New Member

    Apr 24, 2009
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    My brain is fried. I'm going to continue tomorrow. It is all very interesting. Time for a trip to the library. I'll post my findings when I can get something working.
     
  8. bertus

    Administrator

    Apr 5, 2008
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  9. Mr. Arkham

    Thread Starter New Member

    Apr 24, 2009
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    Thank you very much Bertus! This is very helpful.

    Now I just have figure how to tell the circuit to do x when it detects y ! But this is a great start!!
     
  10. Mr. Arkham

    Thread Starter New Member

    Apr 24, 2009
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    I'm currently looking into the following (although I've yet to put it together)

    A hall sensor that feeds into a comparator/schmitt-trigger which leads to an H-bridge. I think hgmjr was right on the money...

    It seems that I also need to do some reading on magnetic strength as it relates to current and windings.

    From what I have read, an H-bridge only works at 24v (I think I saw some that get up to 40A though). Has anyone seen any different?

    Edit: Should I just start a blog on this?
     
    Last edited: Apr 25, 2009
  11. Mr. Arkham

    Thread Starter New Member

    Apr 24, 2009
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    H-bridge update: I think I'm just going to build my own (very simple) H-Bridge using relays. Since I don't need to control speed or anything and just let pure voltage pass in one direction or the other. I don't think transistors are needed then?

    What do you all think?
     
  12. bertus

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  13. peranders

    Well-Known Member

    May 21, 2007
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    A H-bridge can cope with the voltage the transistors are specified for. If you pick 500 V transistors, then you can apply up to 500 V.
     
  14. Mr. Arkham

    Thread Starter New Member

    Apr 24, 2009
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