Control 16 electromagnets

Discussion in 'The Projects Forum' started by Cmginter, Oct 13, 2015.

  1. Cmginter

    Thread Starter New Member

    Oct 13, 2015
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    I am working on a project and I need to control 16 electromagnets.
    • Input Voltage: 12V DC
    • Current: 0.33A
    • Power Consumption: 4W
    I need to turn them on and off very rapidly and switch their polarity. Much like in a motor but I need to have more control of the speed and order. Do I use a micro controller and if so how do I set that up? I'm very much a newbie so the more details the better. Thanks
     
  2. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
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    You could do this with an Arduino Mega with external driving transistors.
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
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    What do you expect by switching polarity?
    What does the electromagnet actuate, if anything?
    Max.
     
  4. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
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  5. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Use an Arduino (microcontroller on a board).

    Then use a motor controller like these (some cheap, lower power ones near the bottom of the page). The dual H-bridge boards can each manage 2 magnets (about $5 each for a 1A unit). Use REVERSE to change polarity of the magnet. Make sure your magnet coils have enough resistance to limit current to whatever motor controller you use.

    https://www.pololu.com/category/11/brushed-dc-motor-drivers
     
  6. wayneh

    Expert

    Sep 9, 2010
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    How do you solve the problem of inductive spikes in a scenario like this, where you have to allow for reverse polarity to the coil? I guess that is handled in a purpose-designed controller such as those linked above?
     
  7. crutschow

    Expert

    Mar 14, 2008
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    How fast is "very rapidly"? :confused:
    Do you know the electromagnet coil inductance?
     
  8. Cmginter

    Thread Starter New Member

    Oct 13, 2015
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    I want to take advantage of the pushing properties of the opposite poles in addition to the pulling of dissimilar poles.

    GopherT - limit the current?

    Crutschow- not sure of the inductance. (I'm a newb). Maybe 2000 times per minute for "very rapidly"
     
  9. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Your magnet's coil will have some DC resistance based on the diameter and length of the wire used to make the coil.

    The voltage you plan to use and DC resistance of the coil will determine the maximum current using ohms law..
     
  10. Cmginter

    Thread Starter New Member

    Oct 13, 2015
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    GopherT - do you do any freelance work? It seems you know what you are talking about. Any chance we can set something up? Or is the forum not a place to discuss this?
     
  11. djsfantasi

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    Apr 11, 2010
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    What are you making? Sounds like some sort of cool rail gun...
     
  12. MaxHeadRoom

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    Jul 18, 2013
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    Seems you do not want to reply, similar to the identical post in another forum?
    Max.
     
  13. Cmginter

    Thread Starter New Member

    Oct 13, 2015
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    I did reply max. I want to switch so I can use the pushing and pulling property of magnetism. They won't be actuating anything
     
  14. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Depends on the rate at which you switch, if switching speed is very high, Inductive reactance comes into play as a current limiter, and you will have to design for AC properties.
    Max.
     
  15. wayneh

    Expert

    Sep 9, 2010
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    In electronics, 33.33Hz would not be called "very rapidly". You may still have problems switching a large inductance at 33Hz, though.

    Is there a reason you can't describe - or show us a photo of - your equipment with more detail?
     
  16. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Then how will you know what pull or push effect you're getting?
    Are you trying to build a perpetual motion machine or over-unity device?
     
  17. Cmginter

    Thread Starter New Member

    Oct 13, 2015
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    I will control the push pull and no I'm not trying to build a perpetual motion machine, just looking for a more efficient motor.
     
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