Do mobile phones wipe the magnetic stripes off of credit cards?
I ask because I am getting a RAZR phone - finally one thin enough I can just stash it in a pocket. But last week on the road, I put my current phone into the pocket of my workout shorts with my hotel keycard and - twice - the keycard’s magnetic code got wiped clean. The hotel staff said it was a common problem.
Are credit cards equally wipe-able by cell phones? Will I have to re-think my whole pocket-stuff distribution strategy and keep my new phone segregated from my credit card wallet??
The Mythbusters set upon magnetic stripe cards with various magnets of differing strengths. They found it incredibly difficult to wipe the information from the stripe, even with the strongest magnets they had.
However, a mobile phone isn’t just a glorified magnet, there’s a lot of radio waves going on there because of the cellular signals. Couldn’t that contribute to the problem?
Given that they are designed to be erased and re-written on a regular basis, and it’s probably regarded as being less of a problem for them to go blank and not unlock a door than the opposite (retain the old information and open the wrong door) I think you are right on the money.
Credit card magstripes are pretty tough, since the banks really don’t want to spend lots of money on new plastics and processing to send out new ones on a regular basis. If you could fritz one with a phone I’d be very surprise, and if your phone was generating that strong a field in your pocket, then you should be worrying about the health of other things than the magstripe…
I would suspect marginal performance by the hotel card encoder before a cell-phone, as radio waves just aren’t going to phase your mag-stripe. A rogue magnet on a wallet clasp or something would be more of an issue, especially if it rubbed across the stripe. (A stationary magnet, as tested for most of that episode of Mythbusters, isn’t going to be a big problem. A moving magnet is.)
The speakers in cell phones (some have two, one for the earpiece, and one for the ringer) have high-strength rare earth magnets. The vibrater motor has some lower strength ceramic magnets. The RF shielding in the phone provides esentially zero shielding for static magnetic fields. There are pole pieces that tend to concentrate and confine the fields though. Modern phones might be compromising this margional magnetic shielding in the name of smaller-lighter-sexier.
I always put the keycard in my wallet. It fits nice there, and I’m unlikely to leave the room without my wallet (except to go to the pool, DAHIK)
I have had this problem with hotel keycards many times and it has never been caused by a mobile telephone. It is almost invariably the fault of either the hotel encoder or the clerk who originally set the card up. I haven’t tested it with a telephone set on vibrate though. The little electric motor in may put out some magnetic fields, but I doubt it. I have perched on top of 1500 HP electric motors without harming my credit cards.
The standard excuse used to be eelskin wallets. Often I have left one card over the visor in the rental car in case I forget the first in my room. When I try the first card and it doesn’t work, 90% of the time the one left safely in the car won’t work either.
The thing about needing high coercivity to erase magnetically encoded data is correct. Back in the day I used to keep a system recovery disk stuck to my cube wall with a magnet, just to tweak the IT folks. As long as you were careful about putting the magnet straight on without sliding the disk would still work.
What RF signal is “near” a cell phone that isn’t “near” to eveything else? They’re pervasive; they’re everywhere. The cell phone doesn’t concentrate them.
I recently had problems with a key card, too. The hotel staff blamed it on my cell phone, but I don’t think I had the key card in the same pocket as the cell phone all three days it happened. I did have the phone on vibrate the whole time, however.
Sound is pervasive too, but you’ll find that pressing your ear to the speaker gives a somewhat different result than listening to it from a difference of 50 metres.
Well, yeah, but in that case you’re putting the receiver right up against the transmitter. In the case of and idle cell phone, there’s just not much activity near it that ain’t everywhere else; there’s nothing transmitting (or rather damned little transmission, just the phone telling the towers where it’s at once in a while). Not to mention the sound coming out of your speaker is far more powerful. Also not to mention that Mamma Zappa makes it clear that her misperception is that there is more activity from random RF waves near the cell phone than anywhere else.
Really? I thought the inverse square rule applied to cellphones as well. My cellphone interferes with my landline if its very close to the telephone, but move it 20 cm away and it’s fine.
Obviously it does. But there’s a power issue. Your cell phone doesn’t transmit but a couple milliwatts. You audio speakers are a couple magnitudes of order higher.
And I’d be rather surprised to hear that your cell phone, when it is inactive (after all that’s what we’re talking about here - the OP had his cell phone in his pocket, so presumably, it’s merely idling), interferes with your landline. No matter how close it is.
In my experience with the programmable hotel cards, it is dependent more on the particular hotel, rather than any abuse I put the cards through. I suspect that some hotels just use cheap crappy quality cards that either don’t reprogram reliably, or have a high failure rate. On a couple of occaisons I’ve gone to the hotel manager and insisted on physically changing to a different card because my particular one was flaky.
Note, most hotel cards now I’m pretty sure use RFID chips instead of magnetic stripes.
I’ve been lurking for a long time and decided to register just for this question, go fig.
I work for a cell phone company (I won’t say which one ) we have had this problem a number of times so far but only with one model, the Motorola pebble. The are 2 fairly strong magnets imbedded in front flip that hold the cover closed. I have gotten it to erase Dave and buster cards, hotel cards and a fairly scratched but still working credit card. Other than that, in my 8 years I have never seen a phone demagnetize a card of any kind.
) we have had this problem a number of times so far but only with one model, the Motorola pebble. The are 2 fairly strong magnets imbedded in front flip that hold the cover closed. I have gotten it to erase Dave and buster cards, hotel cards and a fairly scratched but still working credit card. Other than that, in my 8 years I have never seen a phone demagnetize a card of any kind.