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Electromagnet to repel neodymium magnet?

  1. Apr 7, 2010 #1
    Hello all!

    I'm new to this site and new to electromagnets. I've done some research but now i need help from anyone who is willing. I'm playing around with electromagnets and neodymium magnets. Now i want the electromagnet to repel the neodymium. So first thing I can't use a ferrous material as a core so that weakens the electromagnet. Is there any other material I can use? Second is that i need as much current as possible for only a split second to turn on the electromagnet. I'm using a 12volt car battery. And I want to use some type of capacitor to turn on the magnet. I also need to turn on this electromagnet multiple times a second to repel the neodymium magnet. What kind of setup woud i use? i have sensors that will be turning on the control side of the elctromagnet multiple time a second. but will the capacitor charge in time to keep up with the ciruit? Thanks for anyhelp!

  2. jcsd
  3. Apr 7, 2010 #2
    If the magnet is not guided, it will likely flip over and be attracted back to the coil. Otherwise, you could do one very short pulse which would repel the magnet, but likely cause it to tumble. Check out http://en.wikipedia.org/wiki/Coilgun

    Try disassembling a hard disk drive and put a few volts on the head actuator coil.
  4. Apr 7, 2010 #3
    The electro magnet will be fixed and the neodymium magnet will also be fixed but on a rotating wheel with other ones as well. so when it repels it shoot side ways and spins the wheel.
  5. Apr 7, 2010 #4

    Vanadium 50

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    I hope this is not for a perpetual motion machine.
  6. Apr 7, 2010 #5
    no it will not be. It will run off a 12 volt battery that will be constantly charged with a car charger. I just want to see how fast i can get this thing going and how much torque i can get out of it so that i can use it as a individual wheel motor. Well the application isnt really specific like i said i'm playing around with it.
  7. Apr 7, 2010 #6


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    It sounds like you are just trying to build an electric motor. Have you looked into how different types of motors work, to see what has been done that is similar (or identical) to what you are proposing?
  8. Apr 7, 2010 #7
    Happy experimenting!
    Be advised, though, that making a motor can be fun, but also hazardous.
    Especially if you try to "see how fast it can go" and having no protective housing.
    A spinning object can break apart at high speeds, throwing bits and pieces at high velocity towards your face or other observers.

    Have fun, but be safe by reading-up as much as you can.
  9. Apr 7, 2010 #8
    I like the spirit of experimentation, but be care full, you have a inductor (coil) and are thinking of adding a capacitor- it sounds as though you have a trigger circuit. That could all very easily come together to build a oscillator which produces a AC source from your DC source in your circuit. That you are asking about the charge times worries me that you do not know enough of electronics to keep yourself out of harms way.

    Some other notes- unless your battery is incapable of sustaining the field, the capacitor will not really do much. A car battery by odds will be able to sustain the field from your coil. Charging one capacitor will charge it to 12V (will be a mini car battery once charged) and if the big one is sufficient the cap will only waste energy.

    Do some research on inductors and capacitors- once you understand them, what their values mean, read up on oscilloscopes. So you are aware of the dangers you present yourself.

    Once you have those things well understand remember that field intensity and size in a electromagnetic field is directly related to the Voltage and the Amperage, you cannot make the coil resist anymore then it does- but you can increase the voltage. I would also suggest pulling the magnet, as it reinforces the domains of the magnet instead of flipping them. But that is much more dependent on clever timing of discharge through multiple coils. A great circuit for increasing DC voltage is given http://en.wikipedia.org/wiki/Voltage_multiplier" [Broken] It should be clear that although this circuit is DC in and DC out- there is very dangerous AC conditions inside by the color coated schematics
    Last edited by a moderator: May 4, 2017
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