Database Users

NFC Antenna (Back Cover) can be magnetized and will affect compass

So I've been noticing that my compass would always misbehave (in terms of accuracy, not stability a la Sky Maps). I would get a pretty large static error (30 to 40 degrees obviously not declination); rotations would not be consistent (IE, a 180 degree turn would yield 100 degrees change.); and the magnitude of raw measurements was not like that of the magnetometer I got from Sparkfun.
Turns out the neodymium magnets I had near my desk actually latched onto my phone and magnetized the NFC antenna. I tested this by removing the cover and putting the magnet near the antenna and it sticks. Without the cover on, the compass worked much better.
I've mostly demagnetized my NFC antenna now by doing some magnet sweeps and leaving it near the heater, but I've learned to keep the magnets away.
If anyone is having problems with the compass overall accuracy, removing the back cover may help.

chadrockey said:
Turns out the neodymium magnets I had near my desk actually latched onto my phone and magnetized the NFC antenna. I tested this by removing the cover and putting the magnet near the antenna and it sticks. Without the cover on, the compass worked much better.
I've mostly demagnetized my NFC antenna now by doing some magnet sweeps and leaving it near the heater, but I've learned to keep the magnets away.
Click to expand...
Click to collapse
Why did you have such strong magnets near your desk? lol
chadrockey said:
I've mostly demagnetized my NFC antenna now by doing some magnet sweeps and leaving it near the heater, but I've learned to keep the magnets away.
Click to expand...
Click to collapse
Phones + magnets = bad same as with hard drives, but I guess at least you don't loose files with magnets and phones that would suck...

I use them to test various things, such as magnetic interference on magnetometers in phones/compasses/inertial measurement systems. The magnets used to hold doors closed are very powerful and affect compass heading. Rare earth magnets are also extremely cool.
That's mostly a myth with the hard drives. Floppy disks/cassette tapes sure. I think it takes something like .2 to .5 Telsa to actually start affect hard drives. My largest magnet is only something like .1. In large spinning drives, they all contain a neodymium magnet in the center.
Mostly I was surprised that the NFC antenna could be imprinted by a magnetic field. I was getting a pretty significant field too. The change was something like 10 uT.
Sources:
http://www.pcworld.com/article/116572/busting_the_biggest_pc_myths.html
http://en.wikipedia.org/wiki/Neodymium_magnet

chadrockey said:
I use them to test various things, such as magnetic interference on magnetometers in phones/compasses/inertial measurement systems. The magnets used to hold doors closed are very powerful and affect compass heading. Rare earth magnets are also extremely cool.
That's mostly a myth with the hard drives. Floppy disks/cassette tapes sure. I think it takes something like .2 to .5 Telsa to actually start affect hard drives. My largest magnet is only something like .1. In large spinning drives, they all contain a neodymium magnet in the center.
Click to expand...
Click to collapse
I took apart several old hard drives and found those magnets, so I knew about it but they are exceptionally strong! the two magnets are near impossible to pull away from each other when stuck, you have to slide them I have since lost them though

Thanks for the tip here! Removing the back cover does indeed bring my compass back to sanity. However, I have no idea how to demagnetize the NFC antenna. What are magnet sweeps? Any suggestions?

Didn't saw this thread either.
Thanks will check it later if compass works fine without the back cover

Tried without cover and it works ok!
Now need to find a way to de-magnetize thus damn cover :-\

If you figure out how please let us know.

Google how to demagnetize metal...
Sent from my Nexus S 4G using xda app-developers app

Magnet case with amoled screen question

Can a magnet have a negative effect on my phone screen? I just bought a case the features a magnet clasp.

My understanding is that the Super-AMOLED display is not affected by magnetic fields.

What about the compass?
Unless the magnetic field from the case isn't strong enough to distort it; not sure how much is needed

You will be fine.

Should have no effect unless the screen is operating, the magnet is 3 times the size of an MRI machine's permanent magnet, and the phone is moving through its field at 100 MPH... (the only effect you could get is electromagnetic induction, which would run a current through anything.)
I have the Samsung Galaxy S case, which has a magnetic clasp. It messes up my compass calibration almost every time I put it in, but that problem is quickly solved.

What is all this compass stuff I am hearing about, I just got the phone 2 days ago is the compass that important/ how would I fix a problem with it?

XtaC318 said:
What about the compass?
Unless the magnetic field from the case isn't strong enough to distort it; not sure how much is needed
Click to expand...
Click to collapse
I would wager it uses a fibre gyro compass. The odds of having moving parts inside the phone for the sake of a compass is pretty slim.
Gyro compasses use voltage fed sensors and that is why they (and our phones) need to be calibrated. They are not susceptible to magnetic interference.
I could be wrong, but I would be shocked if they put a magnetic compass in a phone so that it needs to be converted to digital output rather than just put a cheap no-moving-parts-to-break gyro in it that is already digital.

Superbovine said:
I would wager it uses a fibre gyro compass. The odds of having moving parts inside the phone for the sake of a compass is pretty slim.
Gyro compasses use voltage fed sensors and that is why they (and our phones) need to be calibrated. They are not susceptible to magnetic interference.
I could be wrong, but I would be shocked if they put a magnetic compass in a phone so that it needs to be converted to digital output rather than just put a cheap no-moving-parts-to-break gyro in it that is already digital.
Click to expand...
Click to collapse
Thanks for the explanation =)

No problem. Here's some other reading on it if you're bored
Fibre optics: http://en.wikipedia.org/wiki/Fibre_optic_gyrocompass
Different ways of obtaining North and their faults: http://www.seasupport.org/compass.htm

So the consensus is that I'm safe with the magnet case right?

Robman62 said:
So the consensus is that I'm safe with the magnet case right?
Click to expand...
Click to collapse
Yes. You'll be fine =)

Random tidbit: If you put a magnet against the camera lens, it will turn your phone on. I'm using a HD magnet but it might work with a weaker one.

othan1 said:
Random tidbit: If you put a magnet against the camera lens, it will turn your phone on. I'm using a HD magnet but it might work with a weaker one.
Click to expand...
Click to collapse
This happens due to the the magnetic sensor used for the car dock that we never seemed to have gotten. It should keep your screen from going to sleep and, if you were to have the Car Dock application installed, would launch the application.

Discoloration
I bought a case with a magnet clip.
After only 1 week i got a brown-colored spot 1,5 cm in diameter just where the magnet was situated.
Now a couple of months later, the spot is still there.
Don't know how to get rid of it.

A warning to any Note owners

I don't often post here, and and I don't know if this issue has been addressed before, but but I'd like to tell you about my experience with the note:
I received the phone just today, and after bying it online.. All was good, and I already had a case (a faux-leather flip case), waiting, and and put it in immediately. After playing with it for a few hours, and I noticed that there was a dead spot on the screen. But only when using the s-pen, and a few hasty emails and a phone call to Kogan (off whom I bought the phone), revealed that this was a inhear-of-before phenomenon. As of writing, I've yet to receive word whethery they'll accept a return.
However, that would be rather pointless, and since I have since fixed the issue. It seems that the magnet holding the case flap closed was pretty powerful, powerful enough, in fact, to cause the active digitizer to stop working on that of the phone that the magnet was under. After I removed the case the s-pen worked in the spot, as well as the rest of the screen.
So be warned, test your cases if you can before you buy them, especially if they have a magnetic clasp or similar.
(sorry for the prose)

I have been avoiding magnets because of several posts on the subject. There have also been several stating there are no issues.
I prefer to remain safe, and I am grateful for your advice. Magnets near a device relying on magnetic resonance are probably not a good idea. Better safe than sorry IMO.

Strange how some people have this problem. My note has been sitting in a magnet case for 4 months now with no such problems. I guess it depends on the case and how strong the magnet is but I could not do without my case so I will carry on using it for now.

georgios73 said:
Strange how some people have this problem. My note has been sitting in a magnet case for 4 months now with no such problems. I guess it depends on the case and how strong the magnet is but I could not do without my case so I will carry on using it for now.
Click to expand...
Click to collapse
I think it also depends on where the magnet is. Mine was on the back, directly behind the device.

georgios73 said:
Strange how some people have this problem. My note has been sitting in a magnet case for 4 months now with no such problems. I guess it depends on the case and how strong the magnet is but I could not do without my case so I will carry on using it for now.
Click to expand...
Click to collapse
I agree. More testing, and definitely more information from Samsung, is required.

I wonder if it is the TYPE of magnet, not so much the size.
If it is one of those cheap magnets, maybe it won't bother it
as much as the stronger neodymium magnets?

thanks
thanks man.. for sharing this..

I also have avoided the magnet cases due to this fact and have been trying to find cases that use some other alternate means for closure, like maybe velcro instead. I was also even considering that Sweet Case made out of aluminum, but at ~$70, it is rather pricey. I have just been going case less and totally naked with it and so far no problems.

IIRC there is a comment about magnetic fields in the manual...
similarly too, there is a comment about electrostatic fields, so if you are in an environment where sparks fly off your fingertips at intervals be SURE to discharge yourself before touching your SGN.. you may kill the touch response of the screen..
been there, did that, luckily it was a $50 C/H digital thermostat.
EDIT: 2 April 3:00pm
found it: Page 25 of the GT-N7000 Quick start guide states
"Do not store your device near magnetic fields"; and inclusively states "Do not use carrying cases or accessories with magnetic closures"

Man, I guess I have to quit being a Dark Sith Lord. But I have so much fun using Force Lightning to kill all those annoying Jedi do-gooders

I have a Tridea case with a magnet. The magnet is in the part that locks the cover to the back of the phone.
If I fold that piece behind the phone, there is some influence from the magnet. The influence disappears if I leave some space between the magnet and the back of the phone.
It is only a small problem for me, and only noticeable when I play Draw something or similar apps.
My case:
http://forum.xda-developers.com/showpost.php?p=24121326&postcount=330
Sent from the Note taker with Tapatalk

magnets, how do they work??

I have the same issue, I strapped a powermat charging coil to the inside of my casemate tough case, the result is a dead spot directly above the magnet in terms of the spen.
My dilemma is whether to forgo use of the s-pen for the ease of wireless charging.
For the moment as I rarely use the s-pen, the inductive charging coil is staying in place.
The s-pen works as soon as the powermat coil is removed but I'm not sure if it could do lasting damage?
Sent from my GT-N7000 using xda premium

Mystic38 said:
IIRC there is a comment about magnetic fields in the manual...
Click to expand...
Click to collapse
There's a manual? Who knew!
rhn said:
magnets, how do they work??
Click to expand...
Click to collapse
That, my friend, is one of the great unanswered questions of the universe. Gravity is another one. We know what goes on, but not always how. It is mostly at the atomic level, although you have to look into the quantum level to find out more. One day we may figure it out!

Thanks for the warning! I doesn't use a case with magnets, but it's always good to know if I ever would.
/ Jimmy

Signed up to say thanks OP. I too had this situation where i had dramatic penmark deviation on my note. I use notebook style case w/ magnet
I was considering getting it swapped under warranty but then realised the odd behaviour happened in s-memo but not in canvas/paint app. Now i know its the location of the rear magnet on my case. gj op

[Q] magnetic power limit

hi,i was just wondering about the smartcover....
i have a smartcover paid 5$ and works not so fine because the magnetic inside is not so heavy....
so the question is:
how strong must be a magnet to always work with the screen but not so strong to make the tablet having issues with?
i have 2/3 magnets but before trying with the fear of bricking is better ask....

Pikkierello said:
hi,i was just wondering about the smartcover....
i have a smartcover paid 5$ and works not so fine because the magnetic inside is not so heavy....
so the question is:
how strong must be a magnet to always work with the screen but not so strong to make the tablet having issues with?
i have 2/3 magnets but before trying with the fear of bricking is better ask....
Click to expand...
Click to collapse
Bricking? From magnets? LOL
Very unlikely. Highly unlikely. Super unlikely.
You get the point.
I have a case with strong magnets and I have been using it for months and my N7 is just fine. As a matter of fact, it looks like new!
Sent from my Nexus 4 using Tapatalk 2

R: [Q] magnetic power limit
I'm not a nerd and i know that electronic device and magnets are not best friends...i'm just asking....if there's no problem better for me just today a friend of mine gave me a strong magnet,more than the 3 i got
However thanks
sent from rootilapia

scream4cheese said:
Bricking? From magnets? LOL
Click to expand...
Click to collapse
The OP didn't say bricking; he said "damage".
And while there is no magnetic (digital) storage media onboard, there are other components which can be damaged by strong magnets - the prime example would be coil assemblies associated with speakers and microphones (if moving coil tech is used for them). Also it is possible that surface-mount inductors could have their properties altered if they got magnetized to their saturation point. (Depends on what they are being used for).
Take a paper clip and dangle it from a thread above the screen - you will find there are two speaker coils on either side of the USB connector - the closer of the two is only about 3.8 cm from the (apparent) location of the magnetic closure sensor.
@Pikkierello
I would encourage you to use elegance over brute force. A tiny and well placed magnet is a much better idea than a large powerful magnet.
The case that I have seems to work pretty well, and based on the "paper clip and thread" method, its' magnet seems to be located at about 1.1cm from the left hand side and 4.4 cm up from the bottom edge of the N7 (oriented with the USB connector down). Also - I'm not sure if polarity matters - but fwiw, the "pole" of the magnet in my case (the side facing the N7 screen) is the N pole.
You could buy some small magnets, but I would consider the costs involved - it might be less expensive to simply buy a different case.
good luck.

Magnet Neodymium/Ferrous

Can someone settle this for me? There is a lot of talk about whether or not neodymium magnets are safe to use, to make a case a smart case for a Nexus 10. Most of the people talking about it think they are 100% right.
I remember one thread on here where some fool told someone that neodymium & ferrous were both fine but stay away from rare earth magnets because it would kill your device. Neodymium are rare earth magnets!
So anyone actually know the answer? A tiny neodymium disc 10mm x 0.5mm yes or no?

I have nothing to add other than I would like to know as well. Hope someone can chime in with good info.
Sent from my Nexus 7 using xda app-developers app

I'm no engineer, but the only thing that a magnet would destroy on a modern-day computer is a magnetic harddrive; you know, the kind that spin when you have to access the files on them--soon to be a thing of the past!
Your Nexus, and cellphone has no magnetic harddrive, it's a completely different technology, making magnets completely usable when it comes to your portable devices.
And yes, Neodymium magnets, ARE rare-earth magnets. Use them all you want.
That being said, to restate--I'm no engineer!