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Differential magnet lock

 Use magnets to lock things
  (+2)
(+2) 		  [vote for,
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The functional part of the key for this lock is a cylinder. It has magnets of varying strength. When inserted the magnets pull with varying force through a keyway shielded with a strong, thin, magnetically translucent material. Only when the pull is the right strength in the right places bits of metal in the lock (they don't have to be aligned in a row) are attracted to the key, putting the right negative tension (i.e. pulling) on the pins via springs and rods to unlock the door. When the pins are pulled out the right amount an electrical connection is made which unlocks the door with a motor. Thus it is impossible to tension this lock and very difficult to find the right combination of magnetic strength without the key. Easily combined with a combination lock for two factor authentication.
—Voice, Mar 22 2023

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       My design is like your second link, except that the key is not used to turn the lock. It's a cylinder, so twisting the key doesn't tension the lock. Orientation can be assured by printing a line on the key and on the lock which should be lined up. Also my proposed key can have shielded magnets, exposing the magnets in arbitrary directions. This increases security by adding to the magnet placement along the shaft and magnet strength a third factor: magnet exposure by location on the perimeter of the shaft.   

       What part of the original idea is unclear?
—Voice, Mar 22 2023
   

       Something that will make this interestingly difficult is that the spring force will (typically) have a linear change with distance, while the magnet's force changes proportionally to the square of the distance. So, in its simplest form, once you get enough force on the pin to start it moving, it will be attracted all the way to the stop.   

       Some work-arounds: the spring could be wound in a non-linear coil; the pin could be magnetized so you're repelling it, rather than attracting; or the pin could move in a non-linear path, such as rotating around an offset pivot.   

       In my head I'm playing with the idea of mutually interacting pins: say for example the leading magnet on the key is quite strong, and will, upon entry, move the first pin while it's passing quite far - which unblocks the second pin so that it can move, but the first pin will afterward recoil back to its set position.
—lurch, Mar 23 2023
   

       Huh. I seem to have thought up another non-question.   

       Would an EMP have any after-effect on the strength of a permanent magnet?
Would it weaken at all?		   


 

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