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Thread: magnet polarity tester ?

  1. #1
    Woodgrinder/Pickupwinder copperheadroads's Avatar
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    magnet polarity tester ?

    HI everyone this is first post, just ordered some pickups kits from stewmac my question is should i get a polarity tester or use a compass ,also why can't i just use a small magnet like one of those for picking up nut n bolts on a little telescopic handle, will touching the a alnico polepeice with the magnet change your pickups tone or have any effect on pickup

  2. #2
    Pickup Maker David Schwab's Avatar
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    I have one of those Stew-Mac checkers, just because it's handy and I didn't have a compass, but either one will work.

    You shouldn't touch another magnet to your pole pieces, and don't get the Stew-Mac polarity checker too close to alnico magnets either. I hold it a few inches away from the pickup.

    You can also just use a magnet with one side marked, and once again don't touch it to your poles.

    I'd go with the Stew-Mac checker or a compass.
    It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. Albert Einstein

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  3. #3
    Supporting Member belwar's Avatar
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    I bought one from mcmaster carr that works well. Also if you end up getting a Gauss Meter it has a polarity tester built right in. Not a must for a pickup builder, but it sure is handy.

    Gaussmeter - GM200A

  4. #4
    Old Timer defaced's Avatar
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    Would Lenz's Law work? Basically just a coil of wire and a volt meter?

    (Second frame down) HyperPhysics

    If velocity is always the same direction, and the meter is always hooked up in the same direction, then you should be able to determine the polarity of the magnet.
    -Mike

  5. #5
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    Quote Originally Posted by defaced View Post
    Would Lenz's Law work? Basically just a coil of wire and a volt meter?

    (Second frame down) HyperPhysics

    If velocity is always the same direction, and the meter is always hooked up in the same direction, then you should be able to determine the polarity of the magnet.
    Yes, the Lenz's law approach will work. In practice a milliammeter (the modern day descendant of the galvanometer) may be more sensitive than a voltmeter.

    But a compass is simpler.

    The absolute simplest is to put the magnet on a piece of wood or a little boat floating in a bowl of water, and wait for it to orient itself to the Earth's magnetic field. This is how the Chinese built the original magnetic compasses.

  6. #6
    Senior Member -Elepro-'s Avatar
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    if you use a compass.... ot the little boat ..... remember that Earth's magnetic field has north magnetic pole at south geographic pole....

    bye

  7. #7
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    Quote Originally Posted by -Elepro- View Post
    if you use a compass.... or the little boat ..... remember that Earth's magnetic field has north magnetic pole at south geographic pole....
    Yes. The "north pole" of a magnet (not including the Earth itself) is the pole that seeks North in the Earth's magnetic field.

  8. #8
    Old Timer Possum's Avatar
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    ...

    Compasses can sometimes be a bad idea because the needles in them can pretty easily be remagnetized by a strong magnet without you realizing it. I did this with some neo magnets, then realized later the North side of the needle was point South
    http://www.SDpickups.com
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  9. #9
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    I've got the Schatten polarity tester and don't know how I ever did without it. I hate that nagging feeling that I put the bar magnet in the wrong way. The tester tells me right away just by putting it near the slugs or screws.

    It also reassures me that I didn't glue a rod magnet in upside down...

  10. #10
    Senior Member mkat's Avatar
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    I use the Stew Mac polarity tester, which I find much handier than a compass.
    int main(void) {return 0;} /* no bugs, lean, portable & scalable... */
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  11. #11
    Tone Mechanic
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    Get the SM tester, it is worth it. I use it when assembling the pickup and I also use it to double check the polarity just before packaging them up.

    I would actually buy a couple to keep around.

  12. #12
    Old Timer RedHouse's Avatar
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    Quote Originally Posted by Zhangliqun View Post
    I've got the Schatten polarity tester and don't know how I ever did without it. I hate that nagging feeling that I put the bar magnet in the wrong way. The tester tells me right away just by putting it near the slugs or screws.

    It also reassures me that I didn't glue a rod magnet in upside down...
    Same here. I don't like to mark the magnet with a sharpie as some do, and so I use the StewMac tester during assembly.

    In fact I liked that little tester so much I bought a second one, now I can have one on my bench where it belongs, and take the other with me when I go out to do stuff away from my shop.

  13. #13
    Pickup Maker David Schwab's Avatar
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    I use the Schatten tester, AND, mark them with a Sharpie! I hate putting the magnet in backwards.
    It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. Albert Einstein

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  14. #14
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    Quote Originally Posted by RedHouse View Post
    In fact I liked that little tester so much I bought a second one, now I can have one on my bench where it belongs, and take the other with me when I go out to do stuff away from my shop.
    What the hey, they're just $8 or $9. Buy two or more and save on the shipping, which costs as much as one tester from Stewmac.

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