Building Tool-Magnetizer With PC PSU's Debris

Discussion in 'The Projects Forum' started by ByoXFPD, Jun 11, 2010.

  1. ByoXFPD

    Thread Starter New Member

    Jun 11, 2010
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    Hello there!, just registered in this forum,i been always interested in electronics, i actually work on an electronics field (PC related fixing, capacitors, diodes,etc.).

    i kinda have some ideas of what i need to build a Magnetizer(for tools, screwdrivers, and stuff) using some common PC PSU debris, i just wanted to rectify and ask for opinion.

    Id like some specs on this magnetizer (If possible):

    -Push-action switch
    -AC usage (AC to DC thru PSU, for a reasonable magnetic field)(Not battery)
    -3 or more input cavities (for different tool shapes and sizes)
    -AC break-like circuitry protection (pops off when short circuit)
    -As simple as it can be
    -NOT to short-circuit-fry my fingers!

    if you please be so kind to help me build the diagram and a list of the stuff i require from a PSU to build it up, ill draw a detailed diagram if i get it to work and post it for users that could be interested.

    thanks you!
     
  2. coldpenguin

    Active Member

    Apr 18, 2010
    165
    9
    On a personal view of this, I would not turn this into a major project. I would rather it stayed a bit DIY. But I don't like mixing with mains elec when I can avoid it.

    Well, if it is an ATX power supply, then in theory the push action switch should be simple.
    A resistor in series (around 5K?) between ground a push to make switch, and pin14 of the ATX connector would be about right to similate the load of a motherboard in order to allow the power supply to turn on.

    From a personal point of view, I would use a working power supply, and not open it. So long as that box is left closed, there should be little danger of getting a shock of more than 12V, and hopefully the internal fuse of the power supply would be good enough to stop any damage to you. If you are concerned, then there are off-the-shelf RCD sockets which can be purchased to plug any system into, but I don't think it would be necassary here.

    I would use a thick wire, coiled tightly around a wooden dowel large enough for your screwdriver.
    Now my maths ain't working too well at the moment. Lets say your power supply has 3 12V rails, which can supply 10A, 5A and 3A perhaps.
    I think that this would mean, you could make 3 parallel circuits here, one for each hole. In series with the wires above you would need a resistor.
    V=IR
    R=V/I
    So for 12V, and 10A, you would need a 1.2Ohm resistor?
    For 3A, you would need a 4Ohm resistor. To me these numbers do not make sense, they are smaller than I would guess at. I have been trying to work out why myself for the last week (am considering something similar, but with a 5V supply, for moving some small objects).

    That I think is the basics, but I cannot be sure that the resistance is enough to stop the PSU from overloading.

    Here are a couple of resources perhaps:
    http://allphysicsequations.com/elec.html
    http://info.ee.surrey.ac.uk/Workshop/advice/coils/force.html
     
  3. someonesdad

    Senior Member

    Jul 7, 2009
    1,585
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    If you want to magnetize tools, why don't you just use a permanent magnet? Trying to build something from a power supply seems a waste of effort unless you're just interested in experimenting and playing around, but you didn't indicate that in your post. Alternatively, you can buy an inexpensive tool to do this.

    Most of the time in my shop, I'd rather have a tool demagnetized, as things often get magnetized by accident or due to cold working. For others who may be reading this, if you want to make a nifty demagnetizer, find an old electric can opener (or similar appliance) at a local thrift store and take out the motor. Take a hack saw and make a cut through the steel laminations of the motor windings to make a "poor man's recording head" :p. Deburr and put the thing in a box with a push button switch and wire up properly to the AC line. [If you're a newbie to electronics, don't mess with this unless you know what you're doing, as you can electrocute yourself or others.] I made one of these about 20 years ago and it works like a dream. Put the magnetized tool on the air gap, turn on the current, then slowly withdraw the tool.
     
  4. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,750
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    I simply use HDD magnets, works like a charm
     
  5. ByoXFPD

    Thread Starter New Member

    Jun 11, 2010
    3
    0
    Thanks a lot for your opinion, the reason id like to use some common ATX PSU its coz ive a junkyard of PC electronic parts, and id like to give em some use instead of toss em away. id also to build up something stationary not a simple wire around a screwdriver. im sure using just a few PSU parts would make an excellent and safe magnetizer, and yeah, id like to goof around with different magnetic field intensities maybe adding different current levels controller.

    @someonesdad: About the can-opener, well the idea is to use the debris i already have.

    @R!f@@: what exactly do you mean with "HDD magnets", i mean what part do you call like that?, this is interesting since ive a hundred HDDs in my junkyard.

    Im not as experienced with electronics nor get involved with too much math besides amps,wattage,volts or replacing fried capacitors,resistors,diodes.

    Thanks again!
     
  6. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,750
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    HDD magnets, the once inside use to move the head.
    They a really powerful ones.
     
  7. someonesdad

    Senior Member

    Jul 7, 2009
    1,585
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    HDD = hard disk drive for folks who don't know the acronym.

    Be careful when you open drives up and remove the magnets. They can be very strong magnets. If you hold two of them close to each other, they can badly pinch your fingers or slam together and shatter into lots of pieces. Basically, they're not toys. You can search on things like "magnet finger crush" and find some eyebrow-raising stories and pictures.

    I once was examining the UV spectrum of a UV fluorescent tube with my UV spectrophotometer and wanted to see how much I could increase the output of the tube with some magnets (the same principle as magnetron sputtering). Because I used to work at a division of a company that made hard disk drives, I had some powerful magnets handy. I was going along fine, getting good data, when I accidentally bumped the table and the magnets slipped off their temporary holding and slammed together. Unfortunately, the fluorescent tube was between them and in a fraction of a second was no longer an evacuated tube. :p
     
  8. ByoXFPD

    Thread Starter New Member

    Jun 11, 2010
    3
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    oh, I see, once i had one of those magnetic pieces on my hands..and wondered back then where did they came from, but im wondering now, is there any way to make those magnets to increase its magnetic field? or anyway to use em to re-route their magnetic field to other objects so they are equally (more or less) charged?, or were you suggesting to rub it against my tools or something like that? coz ive done so before but didnt get a good magnetic charge on my tools, id like something more "permanent" or strong.

    and yeah..i pinched my fingers once with those already..so, someonesdad story is not quite useful for me anymore lol

    thanks!
     
  9. someonesdad

    Senior Member

    Jul 7, 2009
    1,585
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    You can't make these types of magnets (neodymium or rare earth) yourself, as they require special processing and they have pretty high coercivities, so they're hard to magnetize. You should be able to rub them against your ferrous tools to cause them to be magnetized (carbon steels have low coercivities). If a tool doesn't magnetize well, it's likely a problem with the tool's material, not with the magnet.
     
  10. PackratKing

    Well-Known Member

    Jul 13, 2008
    850
    215
    The easiest way to get a mag / demag tool, is with a small 110v AC shaded-pole motor............the kind found in cheap chinese fans, or the like of a bathroom vent fan motor.

    Dismantle the motor bearings, and shuck the rotor out of it. All you have left is the ac coil, and the laminate frame. Secure it to a small pine board, and place an adequate spst momentary switch in series with the hot lead.

    If you drag your screwdriver on the laminations while it is energized, this will magnetize.

    Holding your driver in the center of the rotor hole in the laminations, not allowing the tool to touch while you energize for say, a three-count, drawing the tool out of the field while it is energized, to a distance of a foot, will demag quite nicely.

    If you are concerned about hooking this directly to the ac mains, :eek: it's how the motor works anyway.........you may want to add a fuse to the circuit.

    Crude, but it works :cool: Same principle applies to a large weller soldering gun element for that matter.
     
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