>>>>We are designing a device that includes some relatively strong magnets. The device is about the size of a cigaret pack and is connected to a laptop using USB. I am afraid that at the end of the day when I throw the device in my computer bag along with my laptop and my wallet that the magnet will de-magnetise my debit cards and erase my harddrive (or even flip a couple of bits).
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>>>>Any useful information would be greately appreciated.
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>>>>Thanks,
>>>>Einar
>>>
>>>While I have no specific data, it certainly seems a bad idea to put magnets and magnetic info cards close together.
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>>That was my initial reaction and I was surprised that the engineers that placed the strong magnets inside the device didn't think of that.
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>Do you have two or more magnets close to each other? If so, what design precautions have been taken to eliminate coupling effects between magnets? Are they attractive or repulsive magnets (In respect to each other)? I wonder if a mu shield would work? This takes me back to my engineering days. :)
>
>Oh yes, one more thing - are these electro magnets or permanent magnets?

I am pretty sure there are two magnets and they are fastened to the case. I am not really conserned about attraction or repulsion between the magnets, but rather the potential destructive nature in relation to other electronic devices.

The magnets are permanent magnets.

The thing is that we do want the magnets to hold the device to another designated object, but we do not want to kill someone that put the device in thir chest pocket and has an old pacemaker and we do not want to corrupt any data stored magnetically.