CE certification and permanent magnets - Page 1
Forum section: electronics / general

author: Just_another_Dave
author_rank: Regular Contributor
timestamp: July 02, 2021, 09:08:51 am
content: This morning I read some news about iPhone 12 Pro causing interferences with pacemakers (https://www.allaboutcircuits.com/news/apples-devices-unsafe-a-lesson-on-the-importance-of-emi-side-effects/). Apparently, the permanent magnets used for aligning the wireless charger produce a magnetic field above the maximum allowed by medical devices to operate correctly.As I haven’t designed commercial circuits that use any kind of permanent magnet before, that made me curious about the maximum allowed magnetic field caused by permanent magnets to know if that’s something normal or if it should have been taken into account before commercialization as the article suggest. Therefore, I searched the iPhone 12 Pro Max manual to check which standards it needs to fulfill to be commercialized in Europe (https://manuals.info.apple.com/MANUALS/1000/MA1964/es_ES/iphone-12-pro-max-ios14-info-y.pdf). To my surprise, even though it warns the user about the possibility of interferences with medical equipment, the manual does not include any measurements about that. I also look for those limitations in the EMC regulation (it is not son uncommon that commercial devices do not fulfill completely the required regulation to get the CE mark in my experience, as in a subject I took while I was studying my MSc degree in electronics we tested the computer screens that the university had and none of them fulfilled the conducted emissions regulation)Consequently, it seems that the maximum magnetic field caused by permanent magnets in commercial devices is unregulated, yet I still that a bit extra be if they can interfere with pacemakers. As I might have missed it, do you know if there is any separate regulation that covers that?Just in case someone is interested in those computer screens, they used a diode-capacitor rectifier without any kind of PFC. My university had found that some years before and notified it, but they made us test them to show us that you shouldn’t always belief the measurements provided in the users manualP.S.: I’m relatively new in this forum and I’m not sure if this is the most adequate board for this question (I chose it because it contained the previous topics about CE certification of electronics product), so feel free to move it should be in another one. Sorry for the inconvenience

author: richard.cs
author_rank: Super Contributor
timestamp: July 02, 2021, 05:16:33 pm
content: Many pacemakers use the presence of a strong magnet to trigger a change in behaviour for test purposes, e.g. they might switch from whatever fancy patient-specific stuff has been programmed to basic pacing at a rate that encodes e.g. the battery status. Pacemaker patients know about this and are warned about strong magnets. Having a pacemaker is kind of like having a food allergy - stuff that is ubiquitous and harmless to most people can be harmful for you, and you are responsible for avoiding it.Realistically the problem is likely a combination of 1) the presence of a magnet in the back of the phone is non-obvious, 2) pocket location, and 3) whilst the paperwork probably does contain pacemaker warnings, so does pretty much every phone or other RF device despite usually negligible risk, so unless it actually says it has a strong magnet it's likely to be ignored.Generally few product standards worry about static magnetic fields, children's toys are the only one I can think of (swallowing magnets is bad). There are also limits for postage, but that's about parcels getting stuck to sorting machines.

author: thm_w
author_rank: Super Contributor
timestamp: July 02, 2021, 08:48:57 pm
content: Yeah postage is the big one I am aware of:https://www.kjmagnetics.com/blog.asp?p=shippingQuote from: Just_another_Dave on July 02, 2021, 09:08:51 amWere the screens of any known brand?You can buy tons of crap on Amazon that will have a CE/UL mark and likely not pass the ratings.

author: Just_another_Dave
author_rank: Regular Contributor
timestamp: July 03, 2021, 02:16:54 pm
content: Quote from: richard.cs on July 02, 2021, 05:16:33 pmThat was what surprised me. I didn’t expect such a powerful magnet to be included nearby to a wireless power converter as it is indeed a ferromagnetic material.Thinking about that, including the most powerful magnet in the charger and one that does not triggers pacemakers in the phone (or just a discharged ferromagnetic ring or an electromagnet that was powered just when the charger is detected) could have avoided this issueQuote from: thm_w on July 02, 2021, 08:48:57 pmYes, as a public university they couldn’t buy the cheapest one on Amazon as our country law forces them to buy anything above one thousand euros through a public offer (it is like an auction in which the cheapest product that fulfills the requirements is chosen). As a consequence most of the equipment they buy is from known brands or at least big manufacturers. However, I’d need to check them again before pointing out any particular brand as I remember that most computers were from Hp and Dell but I’m not sure if the screen was also manufactured by them. Additionally, we also had some computers manufactured by Foxconn