Magnetic Door Keys and Mobile Phones.

[ol' boy]

I will Google this, but thought others may be interested or know why a Mobile Phone disables a Magnetic Room key?

There is nothing more frustrating, you climbed 3 floors, found your room, busting to go to the toilet and all of a sudden your room car fails to open the door!
Yep, you had it near your Mobile Phone for not longer than 2 minutes and its cactus now!

I don't think there has been a place i've stayed where i haven't had to ask them to reprogram the room key multiple times.
Is the Magnetic Card really that sensitive?
How come all our Bank Cards and Credits Cards don't fail in the same way?

How do Radio Waves kill the card?


EDIT: From Google:

In 2009, CPI conducted internal studies in which card users carried mag stripe movie theater cards in their pockets with a cell phone that had no magnetized case around it. After the cards were carried with the cell phone for about three hours, testers started to see the encoding on the stripes being disturbed.
When the problem is truly with the magnetic stripe, outside interference is most often the cause. “The number one issue was cards being demagnetized by being carried next to a cell phone or set on a TV in a hotel room,” Hermanson says. “Anything with an electromagnetic field transmitting from it can cause a mag stripe to demagnetize.”

It happens to me EVERY trip and often 2 or 3 times in the one stay and one location.
The reception Desk people must be over it.....

So, could it be the tiny speaker magnet in the smartphone?
It is the 3G/4G Radio connection?
Or is it the very pathetic card writing process and cheap card?

2nd EDIT: I just released, my leather phone case has a really strong magnet on the flip tag!!! Doh!

Mythbusted

[mtv]

Any device that emits electromagnetic radiation (Eg: RF) can erase/corrupt magnetic striep data.

A mobile phone is frequently transmitting information to base sites, even in standby mode, so close proximity to a card with a magnetic stripe, including credit cards, can corrupt the data.

Having a strong magnet on a phone case will do a much better and faster job of destroying information on a card magnetic stripe.

It's a trap a lot of people discover.

I've had it happen to me as well.

[lsemmens]

And yet, strangely enough, Back in the bad old days of floppy disks. My, then, computer (2 x 5 1/4" floppies and 256Kb RAM) blew a PSU. A replacement, then was almost the cost of a new machine, so, me, being handy with a soldering iron, built an analogue supply to power the box. Worked fine although I couldn't keep the monitor anywhere near the box because of the field emitted by the transformer which was not shielded. None of my disks ever got corrupted, even though they were neeeded tgo run the various programs I was running back then. That said, I certainly did not store them in, or near the machine.

[irritant]

Same thing happens to access cards for booms, electronic security doors, etc.

[ol' boy]

Yet Credit Cards seem mostly unaffected ........ So????

[mandc]

Good point OB. Maybe it's because credit cards have an inbuilt chip and RFID plus a magnetic strip that is not being reprogrammed every day.

Honestly, I have no idea but I often just drop a credit card next to the phone in my pocket and so far no problems.

Like you, I have had to get room key cards reprogrammed.

[gordon_s1942]

I dont know if this still applies but I believe at one time the magnetic strip on a card could be affected if it was placed with another card in a holder, ie an ATM card and a Medicare Card.

[SpankedHam]

You'd likely find the mag stripe on the credit card has a far higher coercivity than a crappy door lock card - ie, the field required to make it unreadable is far far stronger. Placing two credit cards or the like in a holder even with the stripes pressed together won't corrupt them.

Think about it this way, audio tape (if ever there was a poor use for magnetic tape, audio is it) which is tightly wound on the spool and in intimate contact with the above and below layer suffers almost no alteration after years of sitting in a drawer. Tape duplicating machines (not the crap ones that use read / write heads, the proper ones) rely on the master and copy being in contact and passing through a strong magnetic field. If you are doing that with your credit cards, it might be time to rethink the design of that holder.

[ol' boy]

Just like a Wife and a Mistress, i keep the 2 items well apart now
They both work without issue that way

Don't want them ruining the magnetic strip on your Credit Card
(Honey, if you are reading this, i'm just joking ok, i don't really have a credit card)

[Gitch]

Looks like SpankedHam is on the money...

Worth a read...

Better read here

Or google ISO-7811 Parts 2 and 6 are the most relevant to the subject

[gordon_s1942]

Several years ago I had an intermittent problem with the strip not being read in EFTPOS machines and the store owner after it refused to work for the 3rd time, put some Sellotape/Durex over it and I never had any further problems with that card from then on.
The Card was a simple Direct Debit card issued by the NAB and before this 'fix', it had even been rejected by the Banks own ATM's.

[Gitch]

Several years ago I had an intermittent problem with the strip not being read in EFTPOS machines and the store owner after it refused to work for the 3rd time, put some Sellotape/Durex over it and I never had any further problems with that card from then on.
The Card was a simple Direct Debit card issued by the NAB and before this 'fix', it had even been rejected by the Banks own ATM's.

When I was repairing ATM's, I was always told this is because either the mag strip and / or the reader head is actually worn down enough to cause a cross read to the next and previous bits on the mag-stripe... Whether it is true or not I've no idea - but I do remember it used to gum the the hell out of the the card readers (that and all the other crud that is on customers cards)

[gamve]

(if ever there was a poor use for magnetic tape, audio is it)
Prove it. Tape has been around a lot longer than all other formats in audio.