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coil connected to basic stamp: any danger? — Parallax Forums

coil connected to basic stamp: any danger?

debianizedebianize Posts: 5
edited 2004-11-02 20:20 in BASIC Stamp
Hi, I am a beginner and would like to do the following:
I want to connect a coil with a magnet inside to my basic stamp. I want to control the magnet, that can move forth and back, when voltage is applied.
Now I am wondering: How do I connect the coil to my basicstamp? Is there any danger for my bs2, as coils are trying to keep the current flowing when the voltage is unapplied?

Can I simply use pulsout to apply a certain voltage to a certain pin?

thanks a lot

debianizer

Comments

  • NewzedNewzed Posts: 2,503
    edited 2004-10-31 13:43
    Anytime you connect an inductive device to a Stamp, you meed to protect the Stamp from an inductive kickback.· · I would suggest the TIP120 Darlington transistor.· Inexpensive and easy to drive.· You can pulse it or drive it continuously.


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    Sid Weaver
    New Combo LCD Backpack

    http://hometown.aol.com/newzed/index.html
    ·
  • debianizedebianize Posts: 5
    edited 2004-10-31 14:41
    ok thank you, I have ordered it.
    But how do I connect to the basic stamp? is there a link with some circuit similiar to mine somewhere?
    simply p0 and vdd or how?
    thanks
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2004-10-31 14:45
    This will help: http://www.parallax.com/dl/docs/cols/nv/vol1/col/nv6.pdf

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    Jon Williams
    Applications Engineer, Parallax
    Dallas Office
  • NewzedNewzed Posts: 2,503
    edited 2004-10-31 14:46
    Connect the base of the TIP to a Stamp pin via a 1K resistor.· Connect the emitter to ground.· Connect voltage to one side of your magnet coil.· Connect the other side of the magnet coil to the TIP collector.· When you apply a HIGH to the Stamp pin, it turns the TIP on.· The collector goes to logic ground, completing the magnet coil circuit and the the coil operates.

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    Sid Weaver
    New Combo LCD Backpack

    http://hometown.aol.com/newzed/index.html
    ·
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2004-10-31 16:15
    Just a side-note for clarification (I seem to be missing things lately)...His original post seemed to want to move the magnet in both directions...This wiring described will act like a push or pull solenoid, depending on polarity, and would require a spring to move the magnet back.· Reverse polarity would be required to move the magnet back in the absence of a spring.

    Could we get a little clarification from the poster?· Does the magnet need to move both ways, or can it be returned via a spring?




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    Chris Savage

    Knight Designs
    324 West Main Street
    P.O. Box 97
    Montour Falls, NY 14865
    (607) 535-6777

    Business Page:·· http://www.knightdesigns.com
    Personal Page:··· http://www.lightlink.com/dream/chris
    Designs Page:··· http://www.lightlink.com/dream/designs


    Post Edited (Chris Savage) : 10/31/2004 4:22:07 PM GMT
  • debianizedebianize Posts: 5
    edited 2004-10-31 20:23
    well basically it only needs to move it forth one time. The strange thing with my coil is, that no matter in which direction I apply the voltage, the magnet always moves in the same direction. perhaps I should revise my induction physics, but still this seems rather odd to me. So it is actually not even possible to move it back by inversing the voltage. But actually it's enough if it just moves one time, the program eitherway has to be rerun each time.

    so the described circuit should work for me?

    thanks
    debianize
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2004-10-31 21:54
    Yes, it should...I was making sure though because your original post said, "Forth and back."· Also, have you tried reversing the·magnet·inside the coil?




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    Chris Savage

    Knight Designs
    324 West Main Street
    P.O. Box 97
    Montour Falls, NY 14865
    (607) 535-6777

    Business Page:·· http://www.knightdesigns.com
    Personal Page:··· http://www.lightlink.com/dream/chris
    Designs Page:··· http://www.lightlink.com/dream/designs


    Post Edited (Chris Savage) : 10/31/2004 9:56:20 PM GMT
  • debianizedebianize Posts: 5
    edited 2004-10-31 23:10
    unfortunately doesn't work for me. the magnet has a special form, and does only fit in the coil in one way properly. I have put it in reverse, but still it would move the magnet in the very same direction. strange! but it is not essential to my project to have an electromagnet that can move in both directions.
    so thanks alot, I will try to build what you guys advised me.
  • K de JongK de Jong Posts: 154
    edited 2004-10-31 23:23
    Hi debianize,

    The 'strange' behavior of your magnet may be not so strange at all.

    The piston that goes into your coil is probably not a magnet. It is iron and it gets magnetized by the coil and then jumps into the coil when it is activated. As it does not have a magnetic North and South by itself it just jumps in, no matter which direction the current in the coil flows and how you put in the piston.

    That is the miracel smile.gif.

    Klaus
  • debianizedebianize Posts: 5
    edited 2004-11-01 21:43
    what do you exactly mean by: gets magnetized by the coil (coil has to have current, doesn't it?) and then jumps into the coil when it is activated (just current flowing, isn't it?)

    thanks

    debianize
  • JKtechJKtech Posts: 12
    edited 2004-11-02 20:20
    debianize said...
    what do you exactly mean by: gets magnetized by the coil (coil has to have current, doesn't it?) and then jumps into the coil when it is activated (just current flowing, isn't it?)

    thanks

    debianize
    I am going to attempt to answer this question.· Just remember I am not an expert in magnetism.· ··
    ·
    Yes, you do have to have current in the coil.· That current creates magnetic flux around the coil.· When an iron core comes near it is magnetized by the flux and attracted to the coil.· The center of the coil has the highest density of flux so the attraction there is the strongest.· There should be no current to speak of in the piston just the coil.·
    ·
    This is just a basic explanation.
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