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Wire gauge for electromagnet?

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by BroncoDave, Apr 30, 2014.

  1. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    It'll be even harder to get your hands on the parts necessary to use AC :p
     
  2. BroncoDave

    BroncoDave Member

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    I have to at least try but I need a list of parts first. I can submit the list to my college electrical instructor and build it as a class project. I said it before and I will say it again. "There's more than one way to skin a cat".
     
    Last edited: May 12, 2014
  3. tvtech

    tvtech Well-Known Member Most Helpful Member

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    Hi Guys

    I have a feeling in my bones things are going to go wrong quickly here..already massive amounts of Electrical energy are involved.
    Stressed batteries...and now AC Mains added to the mix....

    Bronco..don't force things to work. If what you are trying to do is fighting you every step of way...leave it alone rather.

    There must be a simpler solution...plus if things go wrong quickly...there is nobody there to help you.

    If you had a Team around you and you are trying crazy stuff, it would be safer than doing it on your own.

    That's the best advise I can give from Thousands of Kilometers away. And like you say " There's more than one way to skin a cat"

    Sure...don't be the cat though.

    Regards,
    tvtech
     
    Last edited: May 13, 2014
  4. dave

    Dave New Member

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  5. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    I know these http://theelectrostore.com/shopsite_sc/store/html/power-supplies.html are way out of your price range, but I just wanted to throw it out. Rentals possible too: http://www.electrorent.com/products/power-supplies-electronic-loads

    I never used them, but inductive proximity sensors MIGHT help http://www.ab.com/en/epub/catalogs/12772/6543185/12041221/12041227/Inductive-Proximity-Sensors.html

    Just ideas, nothing more.
     
  6. alec_t

    alec_t Well-Known Member Most Helpful Member

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    Pumping ever more power into the magnet won't necessarily help. There comes a point where the magnetic core saturates. Beyond that point the magnet strength remains constant despite increasing current.
    If we assume that the oven the MOT came from was rated at, say, 850W and that the manufacturer used the minimum sized transformer core they could get away with to keep just below the saturation point, then 850W is all you can usefully push into the magnet.
     
  7. 4pyros

    4pyros Well-Known Member Most Helpful Member

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    "More power"

    You could try one more battery, But you may be better of with a single pole magnet to get that disk magnet out.
     
  8. BroncoDave

    BroncoDave Member

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    Ok guys, I am not trying to do anything dangerous or unsafe. Nobody wants me to get hurt or killed less than I do. tvtech, I can't be the cat. I am NOT a pussy.

    Definately out of my price range to buy. How dificult would it be to scrounge up the parts to build one?

    I wasn't planning on using the same magnet but making a bigger one to handle the load. The microwave transformer magnet is a good strong magnet but only if the object it's lifting is flat and in good contact with at least 2 legs and there is a short distance to the power supply, not 200'.

    I have already started working on a single pole. Nobody answered my earlier post about making one using a 3' x 1 1/2" pipe and wrapping the middle 2' with 100' of 12 AWG solid wire with extra thick insulation. The single pole i'm working on is a 300' spool of solid wire about 2x the size of telephone wire and a piece of 3/4" rebar 6" long for the core. The wire is on a spool about 2" wide and 4" in diameter. I plan to use the same power I am currently using on the microwave magnet. What do you guys think?
     
  9. alec_t

    alec_t Well-Known Member Most Helpful Member

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    If the cross-section of the MOT core is greater than that of your 3/4" bar (or 1.5" pipe) I reckon the MOT core would be better, because (other things, e.g. permeability, being equal) it would cope with a higher Ampere-turns figure before the core saturates.
     
  10. BroncoDave

    BroncoDave Member

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    Huh? Could you repeat that in english please.
     
  11. DerStrom8

    DerStrom8 Super Moderator Most Helpful Member

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    Basically, if your MOT core is bigger, it'd be able to provide stronger magnetism before becoming saturated (maximum possible level of magnetism). By "bigger", I refer to the cross-sectional area that Alec mentioned. Personally I think you'll have better luck with the transformer core.
     
  12. BroncoDave

    BroncoDave Member

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    With the transformer core the object being lifted has to contact as much surface area of the core as possible to be useful. Wouldn't the single pole lift more with less area of contact? The magnet has to be able to hold the weight while being hauled up 115' and being bounced and banged around.
     
    Last edited: May 13, 2014
  13. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hi,

    One other thing to keep in mind is that ordinary steel may have a permeability that is quite low compared to steel made for use in electromagnets and transformers. Ordinary steel can have relative perm around 100 while transformer steel can easily be 1000. That's a ten fold difference. Obviously the transformer steel would make a better core.
     
  14. BroncoDave

    BroncoDave Member

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    So what I should do is cut the transformer core into a single pole core?
     
  15. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hi,

    There is no such thing as a magnetic monopole. Every magnet made or found in nature to date has two poles, one usually called "north" and one usually called "south".

    For an electromagnet, an increase in the distance between faces increases the reluctance which means less strength. So if the core as is has faces 2 inches apart and after cutting one leg off the two faces are 3 inches apart, the one with the 2 inches apart should be stronger.

    If could somehow get the two faces to be closer together than you would have a better electromagnet. Say 1 inch apart. That should pick up smaller pieces better. If you cant do that, try extending one face outward toward the other somehow.

    An idea would be to make a straight piece like the "I' of the original core that is only 1/2 as long as it would take to go across all three faces. Then it would go across only two faces, and if you make a gap of say 1/2 inch at one face then it should pick up smaller pieces better.

    something like this:

    Code (text):

    |-----------------
    |   -----------   |
    |  |           |  |
    |  |           |  |
    |  |           |  |
    |   ---------  |  |
    |------------  |  |
                 gap
     
    (i might have to come back and draw this out better)
     

    Attached Files:

    Last edited: May 13, 2014
  16. BroncoDave

    BroncoDave Member

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    You didn't show where to put the coil. How bout something like this?

    Mag 3.jpg
     
  17. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    Who knows if it would work: http://www.zoro.com/g/00057349/k-G1...pid=G1777797&gclid=CLDYisi9qr4CFRFk7AodgxYAhQ

    Datasheet: http://www.google.com/url?sa=t&rct=...=-FwP29guZFwFpQ-o4kQFNw&bvm=bv.66699033,d.cWc

    So, in theory, you would know if your within 3mm of a ferrous object. http://www.google.com/url?sa=t&rct=...=-FwP29guZFwFpQ-o4kQFNw&bvm=bv.66699033,d.cWc They listed a 5 m sensor too, but not a Zorro.

    So, the device, power supply (which you sort of have), LED and resistor and an extra wire or 3 extra wires. e.g keep magnet off; move around until you detect something magnetic; turn on and pull up.

    ==

    Again, for giggles, I was thinking about "movement". So my first set of giggles is thrusters, say from an airline.
    e.g. 4 jets and "some" way to control. This is just one of my "thinking outloud modes"
     
  18. BroncoDave

    BroncoDave Member

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    You're forgeting one very important factor. The bottom of my well is filled with about 5' of rusty metal flakes that have fallen off the inside of the casing. This well was drilled in 1959. All this may be moot now. I picked up a permanent magnet today that I am sure will lift that weight with no problem. It's off of a huge speaker. It's 6" in diameter and 1" thick. I tried to lower it down with my winch with 15 lbs. of dumbell weights on it but as soon as it reached the water the weights were not enough. The magnet was too strong and just stuck to the casing. My next plan of attack is a flat round peace of steel 7" in diameter with the magnet on the bottom side and 120' of 3/4" steel rod (in 20' sections) bolted to the coenter of the steel plate.
    Mag 4.jpg
     
    Last edited: May 13, 2014
  19. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    How about making the plate from plexiglass?

    or even two sheets separated by standoffs about 1 to 2" long?

    Put holes in the plastic around the outer edge so water can get past more easily?
     
  20. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hi,

    So you are going back to a permanent magnet then?
     
  21. alec_t

    alec_t Well-Known Member Most Helpful Member

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    To keep the magnet from sticking to the well casing perhaps you could use a trolley mount, something like this:
    MagnetTrolley.gif
     

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