4 ms·

Okay, I need a smart person to explain to me why magnets don’t destroy my technology anymore. I swear growing up I was told that even looking at a magnet would

Okay, I need a smart person to explain to me why magnets don’t destroy my technology anymore. I swear growing up I was told that even looking at a magnet would wipe my drives and turn my screen into rainbows. Now we’re sticking them to our phones and iPads and throwing them in our laptop bags…what happened? Was it all anti-magnetic propaganda?

Sinjo 4y ago
We stopped using HDDs and CRTs, and started using SSDs and LCDs.
- kllrnohj 4y ago
  Or more broadly, we stopped using magnetic-based storage & display technology. Hence why random external magents were bad for those things, they used magnetic fields for their operation so other magnets would corrupt things.
CamperBob2 4y ago
In principle, magnets and floppy discs didn't mix, any more than magnets and the stripe on your credit card do. In practice, it takes more magnetic flux than most people would expect to alter either. Magnetic fields fall off drastically with distance (inverse cube, not the usual inverse square) so you pretty much have to deliberately try to damage any sort of magnetic media with a handheld magnet. Magnets were definitely bad for CRTs, because most of them depended on a lightweight metal shadow mask to keep the electron beam from each gun from illuminating the wrong phosphors. If you bring a magnet too close to a shadow-mask CRT, you risk magnetizing the shadow mask (a temporary condition that will eventually be fixed by the normal power-up degaussing cycle), or even warping it, which obviously ruins the tube. Modern hard disk drives are reasonably tolerant of external magnetic fields. In fact, they contain strong magnets themselves. Again, only a small amount of physical separation is needed to keep those magnets from affecting the media. Magnets have no effect on normal electronic circuitry, LCDs, or SSDs, unless (again) you go way out of your way to move a very strong one rapidly back and forth at a very close distance. You might be able to induce enough voltage in an unshielded inductor to damage something, if you tried hard enough. I wouldn't be surprised if it's impossible outside of an MRI machine room. Certain inductor cores won't take kindly to being magnetized, so there's some potential for damage there, I guess. Never seen it happen.
- bombcar 4y ago
  I remember doing a science project involving sticking the larger floppies to the fridge with magnets (maybe even neodymium) and freezing others - not a single one reported any bit errors.
- mgdlbp 4y ago
  Brainiac75 on YouTube did some tests on various electronics (calculator, PDA, PCs, displays) with non-trivial magnets. A Thinkpad with an SSD seemed to be fine; I'm honestly surprised that it didn't even crash: https://www.youtube.com/watch?v=pXITrgRkT5k&t=6m&list=PLiAlc6pI18dVRg-65lFHvl-0h3sjiY3_2 https://www.youtube.com/watch?v=pXITrgRkT5k&t=6m&list=PLiAlc... The magnet is strong enough to directly affect the electrons in the CRT, distorting the raster into interesting shapes: https://www.youtube.com/watch?v=_yEu2R1gYSs&t=2m20s&list=PLiAlc6pI18dVRg-65lFHvl-0h3sjiY3_2 https://www.youtube.com/watch?v=_yEu2R1gYSs&t=2m20s&list=PLi...
- Nathanael_M 4y ago
  Thanks for the thorough response! This is really interesting stuff. I have a few HDD magnets stuck to my wall and their existence confused me. I would never have guessed that the falloff was that big.

Sinjo 4y ago

We stopped using HDDs and CRTs, and started using SSDs and LCDs.

kllrnohj 4y ago
Or more broadly, we stopped using magnetic-based storage & display technology. Hence why random external magents were bad for those things, they used magnetic fields for their operation so other magnets would corrupt things.

CamperBob2 4y ago

In principle, magnets and floppy discs didn't mix, any more than magnets and the stripe on your credit card do. In practice, it takes more magnetic flux than most people would expect to alter either. Magnetic fields fall off drastically with distance (inverse cube, not the usual inverse square) so you pretty much have to deliberately try to damage any sort of magnetic media with a handheld magnet. Magnets were definitely bad for CRTs, because most of them depended on a lightweight metal shadow mask to keep the electron beam from each gun from illuminating the wrong phosphors. If you bring a magnet too close to a shadow-mask CRT, you risk magnetizing the shadow mask (a temporary condition that will eventually be fixed by the normal power-up degaussing cycle), or even warping it, which obviously ruins the tube. Modern hard disk drives are reasonably tolerant of external magnetic fields. In fact, they contain strong magnets themselves. Again, only a small amount of physical separation is needed to keep those magnets from affecting the media. Magnets have no effect on normal electronic circuitry, LCDs, or SSDs, unless (again) you go way out of your way to move a very strong one rapidly back and forth at a very close distance. You might be able to induce enough voltage in an unshielded inductor to damage something, if you tried hard enough. I wouldn't be surprised if it's impossible outside of an MRI machine room. Certain inductor cores won't take kindly to being magnetized, so there's some potential for damage there, I guess. Never seen it happen.

bombcar 4y ago
I remember doing a science project involving sticking the larger floppies to the fridge with magnets (maybe even neodymium) and freezing others - not a single one reported any bit errors.
mgdlbp 4y ago
Brainiac75 on YouTube did some tests on various electronics (calculator, PDA, PCs, displays) with non-trivial magnets. A Thinkpad with an SSD seemed to be fine; I'm honestly surprised that it didn't even crash: https://www.youtube.com/watch?v=pXITrgRkT5k&t=6m&list=PLiAlc6pI18dVRg-65lFHvl-0h3sjiY3_2 https://www.youtube.com/watch?v=pXITrgRkT5k&t=6m&list=PLiAlc... The magnet is strong enough to directly affect the electrons in the CRT, distorting the raster into interesting shapes: https://www.youtube.com/watch?v=_yEu2R1gYSs&t=2m20s&list=PLiAlc6pI18dVRg-65lFHvl-0h3sjiY3_2 https://www.youtube.com/watch?v=_yEu2R1gYSs&t=2m20s&list=PLi...
Nathanael_M 4y ago
Thanks for the thorough response! This is really interesting stuff. I have a few HDD magnets stuck to my wall and their existence confused me. I would never have guessed that the falloff was that big.