MRI disabled every iOS device in facility | Hacker News Reader

MRI disabled every iOS device in facility

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32 pointsasadlionpk10 comments

A possible explanation:

User1:"Were there any iPhones older than iPhone X? iPhone X and Apple watch both have QI inductive wireless charging, so could they have received over voltage?"

User2:"that's.....not the dumbest thing i've ever heard.

if the devices don't have some sort of voltage protection, a rapidly collapsing magnetic field would induce meaningful (albeit brief) amounts of voltage and current."

User3:"Exactly this. Radiology resident here. Had our magnet quench multiple times and fry all of the newer Apple models in the department while my older gen was totally fine."

That is good enough to convince me. Their frequency ranges overlap and the MRI is always emitting pulses with variable frequency. Although there wouldn't be much energy available at the range of tens or hundreds of meters, the sharp pulses could create high peak voltages, cause a breakdown and fry something small. It still could be a made-up story, but it's plausible, at least for devices reasonably close to the machine.

Some TV's/laptops were also affected, apparently. I think it's just coincidence that most devices nearby were Apple ones.

Confirmed - https://www.reddit.com/r/sysadmin/comments/9mk2o7/mri_disabl...

Do magnetic fields propagate that far (outside the room with the magnet/MRI) at relevant strengths?

Going by the leading reply in that thread;

> A coworker used to work for FAA. He said he was sent out to find the source of a high energy source of EMI that was messing with Ohare Airport radar or radio systems. But it was so unpredictable that they had to sit around and wait for another round. They finally got a burst and got a direction. And a rough triangulation. When they arrived at one of the hospitals they had to work with facilities to ask if any new electrical services had been turned up - in fact they had. A big one. A brand new MRI that took a shit load of power. Working with the mri company they found an access panel cover had been left open and literally blasting high energy EMI directly at the airport.

I'd have to say... maybe?

Does anyone remember when TV transmissions were easily interrupted and know what the causes were? I remember on my grandmas TV we'd get a lot of snow when a neighbor was mowing the lawn for instance, he liked to mow right when grandma like to watch Sunday afternoon football.

I was young at the time so never really understood the cause and it stopped happening, possibly as we went from VHF to UHF transmissions. Was the lawn mower causing EM interference or something else, like an electric mower interfering with the powerlines themselves?

Improperly shielded spark plug system in an older mower.

https://www.w8ji.com/electrical_noise_emi.htm

https://www.google.com/url?sa=t&source=web&rct=j&url=http://...

I used to see (i.e. hear) the same effect with an older car which I upgraded from mechanical points to a jerry-rigged EFI system. When I turned on the car, it would have a distinct clicking sound that came through the radio as the coil fired.

Which gets me wondering: when installing MRIs, do they perform test runs at lower powers and try to detect such leak, maybe with some kind of handheld detector?

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