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Driving a Unipolar Stepper with Two Outputs — Parallax Forums

Driving a Unipolar Stepper with Two Outputs

erk1313erk1313 Posts: 12
edited 2004-10-26 16:07 in BASIC Stamp
Hello,

I need to drive a unipolar stepper motor with only two outputs.· I found a simple circuit that uses a ULN2003.· It says that since coil 1 and coil 2 are always the inverse of each other (i.e. if coil 1 is high, coil 2 is low),·you really only need two inputs.·

Can anyone walk me through this circuit? (See figure 1)
http://www.eettaiwan.com/ARTICLES/2002MAR/PDF/2002MAR08_AMD_MPC_AN81.PDF

What is the 5V for? Could I just use NOT gate to provide the inverse signal?

Thank you so so much!!!
-Eric


Post Edited (erk1313) : 10/23/2004 2:36:51 AM GMT

Comments

  • erk1313erk1313 Posts: 12
    edited 2004-10-23 02:44
    idea.gif· AHHH! I think I worked out the circuit.· Correct me, but the 5V should be 12V, else Coil 1 and Coil 3 are always on!!

    Can anyone verify the operation of this circuit?·

    THKX!
  • metron9metron9 Posts: 1,100
    edited 2004-10-25 07:15
    This may help, I just figured out how to make a 12 volt stepper from an old disk drive work using this sites info.
    http://www.doc.ic.ac.uk/~ih/doc/stepper/control2/sequence.html
  • erk1313erk1313 Posts: 12
    edited 2004-10-26 03:02
    hop.gif Awesome!!!! Thanks! That circuit helps out a lot!!! I totally understand now...·

    -Eric

    ·
  • metron9metron9 Posts: 1,100
    edited 2004-10-26 16:07
    Yes, getting the most simple conceps across seems to be a problem for me as I delve into hardware from my software background.
    I still need lots of work understanding this small list for starters.

    1. Reading the spec sheets on com[noparse][[/noparse]ponents
    2. Knowing how to use that information to select the proper size and type for the application.
    3. I still have trouble with simple concept of connecting +5v to one side of a 10k pot, and the 0v ground to the other side
    as in one of the examples in the book I am reading. The center tap is then a voltage controller from +5v to 0v i guess.
    I really need a better idea on the electrons and how they work inside these circuits, just as when I learned to program software
    I went directly to the assembler language and machine op codes on the processor so I had a deep understanding of exactly what
    goes on when a line of code gets executed. If anyone has a suggestion on books that really go deep into this electron stuff that a layperson can grasp the concepts it would be a real help to me as my brain could put these pieces together just like i do with software. One thing with programming, you have all the tools you need at one time, with hardware you have to order it, figure out what you need first as you cant just order one of everything like you have in a software language.

    I did buy a radioshack electronics kit with 200 experiments so a few weeks I should have a better idea how this stuff works.

    I would think there is some software out there that simulates circuits and gives you all the information about a circuit so you can experiment with thousands of devices without blowing stuff up so to speak.

    Good luck with the stepping motor stuff as that is exactly what I am doing now too. I have a NEMA23 5.1 volt, 1.0 amp 5.1 ohm motor and a stepper3 plus1 that I am experimenting with and a copy of Mach2 on an old computer, just got the parallel cable today so by the end of the day the motor should spin a few times. My guy at automationinc is finding me a linear slide device that I can hook up that motor to. I think I am going to like working with hardware much more especially when I can employ software to control it.
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