Levitating sculpture

Discussion in 'General Electronics Chat' started by dmhmaestro, Jan 3, 2014.

  1. dmhmaestro

    Thread Starter New Member

    Jan 3, 2014
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    Hello to all!

    im a sculpture maker from croatia and i have one idea in my mind that i would like to discuss with you... i need your help. i talked to the one "magnet expert" today and he told me i need electro magnets but that makes things more complicated because i dont know nothing about them... and if the electro magnets would be needed inside the "disc" (you will se beneath) than it will not function because it must levitate without wires sticking out. you know what i mean... its somewhat strange he told me i cant do it with just straight magnets n35 or 45... whats you comment on this issue of mine? the levitation would be achieved by tilted magnets facing each other with negative poles....thanks

    [​IMG]

    [​IMG]
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    You can do it with magnets but they are inherently unstable physically.
    The floating magnet will tend to flip over unless you constrain the magnet from doing so,
    for example, two ring magnets with a wooden dowel in the middle.

    Superconducting material will float over a strong magnet. This is self stabilizing because of the way eddy currents are induced.

    Another example of self stabilizing levitation is floating a ping-pong ball over a stream of air. Bernoulli's principle keeps the ball centered on the air stream.
     
  3. Alec_t

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    Sep 17, 2013
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    Your expert was right: you will need electromagnets (controlled by a feedback system).
     
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  4. inwo

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    Nov 7, 2013
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  5. dmhmaestro

    Thread Starter New Member

    Jan 3, 2014
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    thanks for reply... can you get a bit more specific into what do i need and how will i use it.. and also i cannot do this project if the magnets in the disc also needs to be electronic because of the wires
     
  6. matty204359

    Member

    Apr 6, 2011
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    permanent magnets in the part that is levitating could work. but I cant imagine the feedback system would be very easy... something with lasers maybe?
     
  7. Alec_t

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    Sep 17, 2013
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    How big, and how heavy, is the disc?
    Electromagnets to stabilise the levitation will probably be bulky and draw considerable current. What power supply do you have available and where could you conceal it?
     
  8. shortbus

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    Sep 30, 2009
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  9. Little Ghostman

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    Jan 1, 2014
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    I am working on something similar, it isnt as hard as it looks, go onto google and search for a website called the signal path, on there is a video tutorial of magnetic levitation using analogue (opamps), although in the demo the guy dosnt use push/pull just pull, he does mention push/pull.
    In my globe i will be using a H bridge type arrangement with fast switching, feedback will be via a hall sensor to a opamp.
    you can use IR detection for position control, but in your case a hall sensor might be easier to hide and more accurate. Most the videos show the pull or just push method, this is where for example you have a suspended electro magnetic coil, and for sake of argument a hall sensor, personally i am going to use 2 hall sensors on the coil, one top and one bottom, this should cancel out the magnetic field of the coil, so that way any variation in the field is due to the floating magnet position.
    anyway the fixed magnet is pulled towards the electric magnet, the hall sensor reads the distance and outputs a voltage based on this, if the fixed magnet is too close the electro magnet field is decreased, if the magnet isnt close enough its increased.
    The idea behind having push/pull, is because sometimes the fixed magnet can get too close and even shutting the power off completely to the coil, dosnt stop the fixed magnet from jumping up and sticking, so you use a H bridge so you can swap the polarity of the coil polls, that way if the fixed magnet gets too close the coil switches polls and pushes the fixed magnet away (repels).
    It may sound complicated but really it isnt too bad, some use micro's and I am a big fan of pic micro's, but for this i would use opamps. your project isnt too far away from mine, except mine is a globe and will also have to rotate slowly and have wireless lights inside, hopefully via inductive coupling (if I can get it to work).
    Start at the signal path web site video on magnetic levitation. The guy explains it all really well, and gives a excellent demo. then watch other video's from there. If you o the push/pull route you will also need to look at H bridges and MOSFET drivers.
    I hope that is some help


    EDIT

    sorry its 4am and I have just got up, I was being lazy and didnt get you the link. So here it is

    http://thesignalpath.com/blogs/2013/01/28/tutorial-and-experiments-on-magnetic-levitation/

    sorry about that, other people get me links, I should try and be a bit more helpful!
     
  10. PackratKing

    Well-Known Member

    Jul 13, 2008
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    Fixed neodymium magnets in the " floating " disc, and tunable electromagnets in the surround...based on the same idea that coils on the stylus arm for a hard drive, are positioned by altering strength of electromagnets in those coils, to ride on the fixed fields...


    The remaining problem is how to position and make the e-mags adjustable...
     
  11. dmhmaestro

    Thread Starter New Member

    Jan 3, 2014
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    thanks all for reply and thank you for your nice explanation... although i am a bit confused because ive never worked anything simmilar like this before... i would like to work with you and discuss the project in inbox if you agree... i really need someone like you to help me do my project... and i want start ordering as soon as possible because im addicted to the sculpting and making my ideas to life. i have only 21 years and im happy that i find my path(maybe..) :D

    can you please write me in inbox all the stuff i need? i was thinking about buying two freezbes for top and bottom and in the middle bend the wood... that would be pretty light and clean looking... if needed the box can be bigger/thicker
     
  12. Little Ghostman

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    Jan 1, 2014
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    i am a beginner as well, and only 13. please view the vids first. by all means pm me, but i suggest you keep the main talk in here, many great members with huge amount of knowledge. you will do way better keeping it in the forum.
    you are going to have to do alot of leg work i am afraid, and some learning. first bit is first watch the video's and find some others, that way you will get the basic idea. i suggest planning it all first, i dont mind helping with schematics, but i think its too early to go buy stuff. take it slow and plan properly. remember the 6 p's. Propper Planning Prevent's P@ss Poor Performance! :D
     
  13. dmhmaestro

    Thread Starter New Member

    Jan 3, 2014
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    wow, you sound very inteligent and articular for 13year old :) ive watched the video and it dont look very hard to do it but rather expensive equipment and like it need big space that i want to bypass... i dont know what to plan, i only have this idea in my head... i rally dont know how it would be done... if u want i would be happy if u could sketch something for me... please help me with this project because i must achieve it...
     
  14. Little Ghostman

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    Jan 1, 2014
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    ok but give me a couple of days, you dont actually need alot of equipment, start with the simple, like in that video. i will do a circuit diagram and try and work out a strip board design, as i doubt you will want to make a pcb
     
  15. dmhmaestro

    Thread Starter New Member

    Jan 3, 2014
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    nice... i will do whatever it takes, aesthetic is on first place, and performance ofkors
     
  16. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    I think even that would be far too heavy for levitation of ~ few cm, unless you have heavy-current stabilising coils and very powerful magnets. Perhaps use a couple of expanded polystyrene pizza-trays? Or paper plates?
     
  17. Little Ghostman

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    Jan 1, 2014
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    still early testing alec, but so far I have levitated good size pliers with around 800 mA, but I have loads more testing to do, I have also run out of winding wire so I Will order more. I dont think you will do this quickly tho, its not really a rush job type thing. Its not too hard but needs care and thought, not suitable for a beginner like us to rush in.
    Very first thing I ever learnt in electronics was, shortcuts are the long way round, rushing takes longer and failing to plan leads to failure. The clever guys can knock all this up in under an hour, I am not one of them :D, plus I document as I go, it saves time later.
    so far in 2 1/2 years I have started 18 projects and finished 12, two I have ditched as non workable, the rest are ongoing. I might be slow but I get there ;)
     
  18. Alec_t

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    That's encouraging, LG. What levitation height (separation from base/magnet) were you able to achieve?
     
  19. Little Ghostman

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    Jan 1, 2014
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    so far only around 2cm, any more and it began to oscillate with little provocation.
    best idea would be for the OP to get a rough idea of size and weight. also decide how you want to hide the magnets. i would sink a few in a circle just below surface with a thin steel plate above, then a very thing wood slice (if your using wood). you are going to need a fair bit of magnetism and not just on the coil.
    But first get an idea of how weight you will have to lift, the hardest part is designing the coil, i would think you are going to have to wind a custom one, fairly wide but not too thick, and probably alot of turns. Hand winding takes ages to do well!
    Once you give me the weight i will try different coils, hopefully we can keep the current under 3A, preferably 2A.
     
  20. gerty

    AAC Fanatic!

    Aug 30, 2007
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    The schools Assistant Director has a similar globe, major exception..his is covered in dents from when the power goes off and the globe hits the floor. Kinda sad looking, but it still works.
     
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