Need solution for electromagnets project

Discussion in 'Embedded Systems and Microcontrollers' started by prabhubng, Feb 23, 2013.

  1. prabhubng

    Thread Starter New Member

    Sep 29, 2009

    I am new to electronics I am trying to do a project but I am unable to find suitable design for it, I am using Arduino board for my prototyping, the project is, I made a matrix of 8x8 small electromagnets which is working with 12v and 250 mA, basically these electromagnets pushes a small neodymium disc magnets on other side.

    I tried to drive this using 74HC595+ULN2803 combination for each column and I am able to drive them individually, but my problem is I need to also switch the power direction individually so that the electromagnet pulls the neodymium disc magnets back, now I am not able to decide how I can drive those individually with bidirectional power switch from code.

    To get an idea this project similar to flip disc displays where the electromagnets try to push and pull the neodymium magnets so that the disc flips.

    It will be really helpful if someone can give me suggestions over this issue and sorry for my bad English.

    Thanks in advance,
  2. MrChips


    Oct 2, 2009
    Search for H-bridge.
  3. JDT

    Well-Known Member

    Feb 12, 2009
    An H-bridge for each of your 64 electro-magnets is a lot of transistors.

    It might be a good idea to have a split power supply with either positive and negative supplies or a centre rail. Then you will only need a "totem pole" of two transistors for each electro-magnet.

    If you are making your electro-magnets yourself, think about designing them to work from a voltage and current that could be supplied by an integrated circuit of some kind to reduce the number of components.

    Research the semiconductors before winding the coils!
  4. tubeguy

    Well-Known Member

    Nov 3, 2012
    Here's an example of a chip:
  5. JDT

    Well-Known Member

    Feb 12, 2009
    That looks good because there are separate logic and enable inputs for each channel.

    This is important because each channel out needs to be pulled high, open circuit or pulled low individually.