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  1.    #1  
    Mine, seems to be getting weaker already, ie. it doesn't seem to hold the pre as strong as it once did. Anyone else seeing this?
    Palm V > samsung i500> treo 650 > treo 755p> Centro> Pre
  2. #2  
    Actually, now that you mention it, i remember first trying out the pre on display at my local sprint shop. when i went to grab it of the TS, I thought there was a button to release it. It was like taking the sword from the stone.

    Then after getting home and putting my pre on my TS, i felt a significant difference when taking the phone off. It felt much easier than the display at the store.

    With that said, i haven't noticed any difference when taking my pre off of my own TS.
  3. #3  
    Mine still holds exceptionally well, however, magnets can lose magnetism the following ways:

    1) Via heat: ferromagnet materials will lose their magnetism if heated above a point known as the Curie temperature. At this point, the energy being put into the magnet from the heat will permanently disrupt the magnetic domain structure of the material, turning it into a paramagnetic material [a similar effect occurs in materials called hard ferrites, which exhibit a form of magnetism called ferrimagnetism; the analogous temperature for these materials is known as the Neel point]. You would have to re-magnetize the magnet again, either in a solenoid or with another permanent magnet, in order to restore the magnetism. If you heat a magnet up a little bit, it will lose some of its magnetism, but on returning to room temperature [depending on how high it was heated, and on the shape of the magnet itself], full magnetism can be restored.

    2) Via a demagnetizing magnetic field: permanent magnets exhibit a characteristic called coercivity, which is the ability of a material to withstand being demagnetized by an applied magnetic field. Modern permanent magnet materials such as Sm-Co and Nd-Fe-B have high coercivities; older materials such as Alnico or ceramic [hard ferrite] materials have lower coercivities. With a strong enough magnetic field of opposite polarity, it is therefore possible to demagnetize the magnet [whether this comes from another permanent magnet, or a solenoid]. Interestingly, an opposing magnetic field is sometimes applied to a magnet in order to 'knock it down', or to lower its overall magnetic output, so that it can be used appropriately in an application.

    3) Via shock: this really only applies to older materials such as magnetic steels and Alnico materials; the mechanism that creates coercivity means that they are susceptible to being demagnetized if enough energy is transmitted through the material via a shock, such as being dropped or hit with a hammer. Modern materials do not suffer this type of problem.
  4. #4  
    Quote Originally Posted by danman_6 View Post
    Actually, now that you mention it, i remember first trying out the pre on display at my local sprint shop. when i went to grab it of the TS, I thought there was a button to release it. It was like taking the sword from the stone.

    Then after getting home and putting my pre on my TS, i felt a significant difference when taking the phone off. It felt much easier than the display at the store.

    With that said, i haven't noticed any difference when taking my pre off of my own TS.
    Perhaps there is natural variation between different Touchstones? They might not all be the same strength.
    Palm III-->Handspring Visor-->Sony Clie PEG-NR70-->no PDA -->Palm Treo 755p-->Palm Pre-->HP Veer
  5. #5  
    pogeypetey's information is accurate. There really should be no measurable difference in the magnet's strength throughout the life of the phone, and in fact, much, much longer.
  6. #6  
    Wow. My head hurts now. Hopefully the coercivity of my touchstone is strong.
  7. dave75's Avatar
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    #7  
    And the temp that the Touchstone gets up to isn't enough to damage the magnets. You probably have improved your technique at removing the Pre from your TS.
  8. #8  
    The phone will literally melt before the magnet's coercivity can permanently change.
  9. #9  
    I would say, at the very least, 3 and a half months.
  10. awrnsmn's Avatar
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    #10  
    I agree. Should last beyond the life of your phone.
  11. #11  
    The electromagnets in my speakers have now lasted 40 years.

    Can't say the same for the felt that surrounds them.

    Physics is a tough subject, eh?
  12.    #12  
    Thanks for the physics lesson, obviously I must be better at taking off the TS or all that working out is paying off
    Palm V > samsung i500> treo 650 > treo 755p> Centro> Pre

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