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MOSFET or Rheostat or Potentiometer pros and cons?

  1. Jun 20, 2017 #1
    Preface: I'm a chemical engineering undergraduate student but as small-time and noob electrical engineering hobbyist. I really only have minimal experience in circuitry and the like.

    I want to build a series of electromagnets with a variable their strength in order to levitate an opposing circular Halbach Array up to and from a certain height. This array will be separated from the electromagnets so I don't have to worry about it "sticking" to the electromagnets when off. There will also be a guide pole through the center of the array so that it stays balanced.

    What would be the different factors I should consider when using a either a potentiometer or a MOSFET or PWM or some other kind of voltage variant?
    Are there other kinds of energy controllers, that I could potentially use?
    How do they differ from each other?

    Thank you so much in advance.
    Last edited by a moderator: Jun 20, 2017
  2. jcsd
  3. Jun 21, 2017 #2


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    Rheostats and potentiometers are just physically different versions of exactly the same thing and for DC current they have the same effects. If you don't care about power loss/waste in those passive current limiting elements then either one would be fine. If you would like to avoid that loss/waste at the expense of some complexity (and cost), look into active current controllers
  4. Jun 21, 2017 #3
    Thank you for the response!!

    That would be perfect, but I need the device to either run on battery power or through an outlet (Battery being the preference as I don't want to deal with the craziness that is a transformer...Yet) . I also want to be able to create my own variable speed motor (and electromagnet) controller, without having to buy new active current controller.

    Any tips?
  5. Jun 21, 2017 #4


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    If you don't care about reduced battery life due to the waste in a pot you have no problem. Is this something that you plan to run for extended periods?
  6. Jun 23, 2017 #5


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    Powerful electromagnets tend to need large currents. Got any more info on the electromagnet? Size? Field strength?
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