Coil winding

Discussion in 'General Electronics Chat' started by dayanj, Oct 18, 2010.

  1. dayanj

    Thread Starter New Member

    Sep 29, 2010
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    I am winding a coil to get a constant magnetic field for my experiments.
    I am using a aluminum bobbin and winding insulated copper coil on it, I need ten layers.
    I was trying to wind it manually but its hard to get neat winding.
    Can someone suggest me any help with this?

    someone said I can use epoxy after each layer to keep that layer fixed, has anyone used it like that? if so which type of epoxy?
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    That has been a problem for me for decades. You almost need to make something mechanical to do it right. Riff has made something for speakers you might be able to mine for ideas.

    My voice coil winder

    If you are after a magnetic field aluminum is one of the worst materials you could use. You need a ferrous material, such as iron (iron nails are typical for kids with science projects) to concentrate the magnetic field.

    I've tried using super glue, with poor success.

    My personal vision of such a device is something with a 6 digit counter, up and down, with a gear box to slowly feed wire on your spindle. You will also need a place to put the spool of wire and some sort of clamp for the wire, so you can stop the process and walk away if needed.
     
  3. sceadwian

    New Member

    Jun 1, 2009
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    Magnified eyeglasses, a steady hand and patience...
    Patience is the most important ingredient if you want to do this by hand, practice is going to be required, a simple dab of warmed wax that is immediately cooled will temporarily hold a coil winding. Hot glue will work exceptionally wel.

    Every wire wound AM antenna I have ever taken out of a device all used some type of basic wax as a potting compound. The voice coils of every speaker I've ever taken apart is all mechanically wound =)
     
  4. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    How about using double sided tape between layers. It would hold the first layer and hold the next layer as it's being wound. You could even put alayer of the tape on the former to keep the first layer in place while winding it.
     
  5. sceadwian

    New Member

    Jun 1, 2009
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    It will also act as a capacitor dielectric and effect the distance between each winding layer enough to lower the inductance. A simple tiny dab of warm wax is all you need to keep the wires in place during winding.
     
  6. beenthere

    Retired Moderator

    Apr 20, 2004
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  7. SgtWookie

    Expert

    Jul 17, 2007
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    Since you didn't put your location in your profile (hint, hint! Select the "User CP" link at the top of every page) we don't know where you are.

    If you're in the USA, Radio Shack sells a 100uH inductor that is wound on a ferrite rod. This ferrite rod could be a good candidate to use as a base for your electromagnet.
    Link: http://www.radioshack.com/product/index.jsp?productId=2103978

    If you have an electric drill, that can help to speed things up. It takes patience and practice to get good results. Fast-drying clear lacquer, either spray or dabbed on with a brush, can be used to hold the layers in place.
     
  8. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Super glue , just a dab is enuf to hold the coil.

    But should cover it will tape to avoid unraveling when in use. Slight heat up will loosen super glue.
    Believe. I had bad experience like tht.
     
  9. radiohead

    Active Member

    May 28, 2009
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    take an automotive 30A relay apart and use the existing coil. If it will actuate relay armatures, it will generate a magnetic field. My two cents.
     
  10. marshallf3

    Well-Known Member

    Jul 26, 2010
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    It also helps (really kind of necessary in a multi-layer coil) to have end pieces on the form to help retain the wire around it. These can be temporary such as a couple of washers held in place with a nut & bolt.

    Although occasionally hard to find except in some of the larger stores or hoby shops lacquer is an excellent inter-winding adhesive, it's been used for ages. Being alcohol based it doesn't tend to dissolve the enamel on the wire you're winding with.
     
  11. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    [​IMG]

    This will be about the closest you can come to 'uniform' mag field, at the home hobby cheap user level. Lots of $$$$ for special equipment need not apply
     
  12. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Can you explain to me how the addition of double sided tape that is at best 0.004" thick will make a layer of wire into a capacitor?

    I have always been under the assumption that a capacitor was made by two or more conductors of a different potential separated by a insulator. In the case of a coil the wire layers are at the same potential. Didn't know there could be a single sided capacitor.

    I have taken apart coils that have a layer of paper between the layers, does this make the capacitors/capacitive also? Every time I think I'm finally getting the hang of this stuff I'm told something different/new!
     
  13. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    That is not true. Even in DC the wire has some resistance, so the wire at the end of two different layers has different potential.
    In AC it is even more apparent, becasue the coil itself has some voltage across it, so the there has to be voltage differential between turns.
     
  14. sceadwian

    New Member

    Jun 1, 2009
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    shortbus, the description of two isolated metal plates separated by an air gap at different potentials is how all intentional capacitors are made, but the case of a stacked wound coil is not a case of intentional capacitance, any two metal objects in close proximity separated by an insulation layer will effect some degree of capacitance, even if this 'other' piece of metal is the same piece of wire that on the next rotation around the spool. This is going to happen no matter what you do, I was just saying using something like double sided tape which is probably going to have a decent poly backing is probably not the best solution if you want to minimize capacitance, it might not even make a lick of difference for this application but I drop things like this in the forum quiet frequently just so that people are aware of it's existence.
     
  15. marshallf3

    Well-Known Member

    Jul 26, 2010
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    Capacitance exists between any two conductors regardless of spacing or material between them. As a matter of fact many HV capacitors are manufactured and packaged in a total vacuum - absolutely nothing between the conductors that would normally be called the dielectric.
     
  16. Tesla23

    Active Member

    May 10, 2009
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    Increasing the distance between two conductors by inserting a piece of dielectric between them can only reduce the capacitance, regardless of what the dielectric constant is. Think of two parallel plates each with a thin layer of varnish and put them touching. Now move them apart by inserting a layer of some other dielectric - the capacitance will reduce.

    If you were talking about potting the inductor, that is replacing air dielectric with something with a higher dielectric constant, keeping the same spacing between the wires, then the capacitance would increase. However, increasing the spacing between wires by inserting a layer of dielectric will tend to decrease the capacitance.

    Of course, the situation here is not 100% clear as some double sided tapes will 'squish' between the windings and both separate the windings whiles filling in some air voids, whereas some others will maintain their shape and provide a nice flat former for the next layer, these clearly separate the windings.
     
  17. sceadwian

    New Member

    Jun 1, 2009
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    Absolutely right there Tesla, sorry I opened my mouth a little too soon without knowing what I was talking about properly, thanks for the correction, something I'll want to read into a bit more.
     
  18. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    OP over board.....drowning with :confused::confused::confused:.

    Guys..please..what did OP asked for? :cool:
     
  19. sceadwian

    New Member

    Jun 1, 2009
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    All on topic though Rifaa, you notice the OP hasn't come to focus the original comments, so the rest of us users are under unwritten forum law required to try to further the conversation even if the person that started it isn't here anymore.

    Mind you they might only log on once every week unlike the rest of us lurkers =)
     
  20. Rbeckett

    Member

    Sep 3, 2010
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    I guess I cheat, I use my mini lathe with power feed for a uniform layer and overlap. It's pretty quick and produces some signifigant layers in a very short time. A dab of varnish between layers and a good dip when done and I can wind inductors or transformers on demand. Know a freind with a mini? Definately worth a look
    Bob
     
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