Noob questions about coils and such

Discussion in 'The Projects Forum' started by DarkMavis, Oct 9, 2015.

  1. DarkMavis

    Thread Starter New Member

    Aug 24, 2014
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    Okay, so I guess that more current means a stronger magnetig field, as does more turns in the coil. Obviously thicker wire allows more current, but fewer turns, because of limited space. I know the material the core is made from affects the strength...BUT surely it's not really affecting the overall "Amount" of the field and just focusing it all in a single direction? Is that right? I don't see how it could be any other way. If the actual field is somehow...more, then...HOW? Surely it can't be.
    What other factors affect how far the field extends? I guess a longer core would allow more of the turns to be closer to the core, rather than winding them over existing turns, and I'm aware that winding all the way to the ends of the core is less efficient, because those windings nearer the end don't have as much of their field running through the core.
    I'm trying to pulse a coil on and off at around 50khz. I guess an iron core would get hot at that kind of frequency, but I'm sure ferrite is more than fine with it. However...am I right in assuming that the ferrite is only increasing the field strength (And therefore distance, since it's the distance I'm more concerned with) in one direction? Presumably axially along the length of the core. BUT what does the presense of the core to to the distance the field extends in other directions? SURELY, it reduces it, right? Since you can't get something for nothing. No having your cake and eating it. (at least not at the same time, which that dumb saying doesn't seem to specify)
    So to simply have a coil create a field as far as possible in all directions, (okay, not ALL, since I don't see how that would work, but, to extend in more directions than the same coil with a ferrite core) is it not better to use an air core? (Which I guess means a hollow coil?)
     
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  2. wayneh

    Expert

    Sep 9, 2010
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    If your goal is to project a magnetic field in air (or vacuum) as far and wide as possible, then I think you are correct that eliminating the core will help with that. Otherwise the core just sits there absorbing energy and turning it into heat. A core is useful for changing the inductance of the coil or coupling two coils. It doesn't sound like you are doing either.
     
  3. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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    I have no idea what you're doing but if you want a uniform field in a large space a Helmholtz coil might be something to look at.
     
  4. ranch vermin

    Member

    May 20, 2015
    85
    2
    does the wire itself gain remanence, or do you need a core for that??
     
  5. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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    I would assume his wire is not ferromagnetic.
     
  6. DarkMavis

    Thread Starter New Member

    Aug 24, 2014
    20
    1
    Yah, just regular magnet wire. I think I'll experiment with different shapes. I'm wondering if, number of turns being equal, would one long row of a single layer be better than something with a more square side-on shape. I think not
     
  7. wayneh

    Expert

    Sep 9, 2010
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    Define "better". You haven't stated a goal.
     
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