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Strongest Electromagnet using 2 AA bateries

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by Trisorion, Aug 17, 2008.

  1. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    You've started one thread, don't make duplicates about the same question - they WILL be deleted, and you WILL be banned - moderator.
     
  2. Trisorion

    Trisorion New Member

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    Thank you nigel.
     
  3. Hero999

    Hero999 Banned

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    It makes me smile when Nigel speaks like this, when I read his stern moderator posts I hear the voice of a very strict teacher.
     
  4. dave

    Dave New Member

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  5. Willbe

    Willbe New Member

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    Are you allowed to parallel your battery with a capacitor?
     
  6. Willbe

    Willbe New Member

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    Me too. A car battery so weak it can barely crank the engine can be boosted by running the headlights for a minute or so.
     
  7. Trisorion

    Trisorion New Member

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    I could run a capacitor in parallel, but please excuse my inexperience, what would that do?

    Also I think that the internal resistance heating/cooling relationship might be different depending on battery chemistry. Car batteries are lead acid, but I always thought NiCd was known for its high discharge potential, but I will do some tests either way. And I will make the coil slightly less resistance than I calculate it needs.

    This post got lost in the shuffle. Does anyone know the answer to that question?
     
    Last edited: Sep 7, 2008
  8. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Forget about using a lead-acid battery. You said the rules spec'd two 1.5V batteries but lead acid is 2V per cell.
    Maybe the rules do not allow Ni-Cad or Ni-MH batteries that are only 1.2V per cell.
    Alkaline batteries are 1.5V per cell. Two alkaline D cells might produce 5A.

    Your question about adding many coils and overloading the battery was answered by me. The internal resistance of the battery will show its ugly head which reduces the voltage to the coils which reduces their current.
    Then most of the power of the battery will heat its internal resistance instead of powering the coils.

    Forget about heat causing the internal resistance of the battery and resistance of the coils to rise. The temperature takes time to rise and it won't rise much in only 20 seconds with maybe only 5A of current.

    Forget about connecting a capacitor in parallel with the battery. A capacitor's voltage drops sharply when it discharges because it is not a battery. It would need to be as big as your house to provide 5A for 20 seconds.
     
  9. Willbe

    Willbe New Member

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    Last edited: Sep 8, 2008
  10. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Transient magnetic power.
    Enough power to draw paperclips within one kilometer? One centimeter?

    I think paperclips would just twitch a little then the capacitor is discharged.

    The power comes from the battery. If the battery is used to charge a huge capacitor then the battery will be weakened. The capacitor uses up the battery's power.
    You don't gain anything except the ability to draw paperclips from a distance which is not needed.
     
  11. Sceadwian

    Sceadwian Banned

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    Depends on what you're allowed to use. You could get exotic and use the charge pump circuit from a disposable flash camera to charge a large capacitor bank to a few hundred volts from a single AA battery. Could do more than twitch a paperclip with that. I've always had the urge to use the stretch film we use at work and some foil to make a very large capacitor. Although it would be limited for pulse discharge by the inductance of it being a large coil I think I worked out the thickness of the film we have at work would alllow a safe charging voltage of 200 volts. A couple roles of super heavy duty aluminum foil and a few rolls of poly stretch film could be fun.
     
    Last edited: Sep 15, 2008
  12. audioguru

    audioguru Well-Known Member Most Helpful Member

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    A capacitor must be huge to provide high power for 20 seconds.
     

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