How do you wind a toroidal inductor?

Discussion in 'General Electronics Chat' started by noob_whale, Dec 28, 2013.

  1. noob_whale

    Thread Starter New Member

    Dec 28, 2013
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    Hi, I'm just starting out with electronics, and recently, I've been attempting to make an electro-magnet out of a toroid wrapped with magnet wire. For whatever reason though, the toroid isn't producing a noticeable magnetic field. I've been able to make a simple electro-magnet from wrapping magnet wire around an iron bolt, but the toroid isn't working for me.
     
  2. MrChips

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    Oct 2, 2009
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    You need a toroid winding machine.

    With a properly designed toroid the magnetic flux is contained in the toroid.
     
  3. Dr.killjoy

    Well-Known Member

    Apr 28, 2013
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    I could be wrong but what you are making is what we call a choke,coil, transformer .. ..

    http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/toroid.html
     
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  4. Dr.killjoy

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    Apr 28, 2013
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    You can make a electromagnet out of a Toroid ????
     
  5. tcmtech

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    Nov 4, 2013
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    You would have to wrap the wire around the outside of the toroid core not through it.
     
  6. atferrari

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    I have no idea how that could work but it seems that a conventional core would be simpler if no effective.
     
  7. Shagas

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    May 13, 2013
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    Wont the toroidal shape of the electromagnet cancel the poles out therefore yielding no result?
     
  8. noob_whale

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    Dec 28, 2013
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  9. GopherT

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    Yes, that is the whole point of a toroidal core. Think of wrapping wire around a nail to make an electromagnet - north at the head and South Pole at the point. Now, bend the nail into a circle (toroid) and North cancels South. The magnetic field should be perfectly inducted through the circumference of the toroid and no emi outside the toroid.

    toroid cores are used in transformers for high-end audio to specifically prevent any signal cross-over from the transformer.

    If you want to make an electromagnet, break/cut the toroid in half. If you score it and tap it, it should crack. If it is an iron powder core, you can cut it with a saw - the powder is held together with epoxy. Or, more simply, just use a nail.
     
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  10. wayneh

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    Sep 9, 2010
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    Not outside of the toroid, ideally. There may be some small leakage but very little compared to the field contained within the toroid. Look up "gapped toroid" if you want to get a strong field using a toroid.
     
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  11. MaxHeadRoom

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    Jul 18, 2013
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    One reason why toroid transformers became so popular in audio equipment, the field is contained within the toroid, so minimum Hum pickup or transfer.
    And also makes them more efficient than EI types.
    Max.
     
    Last edited: Dec 28, 2013
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  12. noob_whale

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    Dec 28, 2013
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    Thank you all! The information was really helpful.
     
  13. bertus

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  14. ian field

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    If you got loadsamoney you can get a toroid winding machine - otherwise it can be difficult and tedious.

    If the winding wire isn't too long, you can sort of halve the difficulty by threading the wire through and hold the 2 ends letting the weight of the toroid fall to the middle - then wind the 2 ends on in opposite directions.

    It simplifies things if you wind one end on, then deal with the other - you can tape the free end to an AA battery or other weight so it hangs without tangling and kinking while you wind on the first end.
     
  15. WBahn

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    Mar 31, 2012
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    Good. You are getting the results you want -- you just don't realize it. The primary purpose of using a toroidal form is that the magnetic flux is, ideally, completely trapped within the torroid. Thus, it isn't accessible for you to use a magnet outside of that. If you were to cut a slot in the torroid, you would get a good magnetic field in the gap.
     
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  16. #12

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    Nov 30, 2010
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    Don't worry too much. I pulled a similar stupid a few weeks ago when I tried to wrap 100 turns around a wire and use that to measure current in the wire. Dummy! That shape of coil doesn't cut across any lines of the magnetic force. You have to remind your self to think about the 90 degree directional shifts between current and magnetism.
     
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  17. ian field

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    Ferrite isn't great for making electromagnets - as long as the OP is using DC to energise the coil, a nail (or bunch of nails) can't be beat.
     
  18. noob_whale

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    Dec 28, 2013
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    What do you mean about 90 degree directional shifts? Thanks.
     
  19. noob_whale

    Thread Starter New Member

    Dec 28, 2013
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    So, if I were to use a gapped toroid, the magnetic field would only be at the two poles on each side of the gap? Is it possible to make a magnetic field only in the "hole" of a full toroid?
     
  20. MrChips

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    Oct 2, 2009
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    Google right hand rule.
     
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