Happy B-day Beck!

I don't think you can punch in bank cards by hand. At least, the machines I've always used didn't let you...

Haha... who needs fancy bug tracking software when you've got "bug! bug!"?

Anyway, I think I fixed the duplicate post problem and the wide textbox problem. Thanks, guys.

...well, the good news is that the "new look" message board is good, for serious.-keep up the good work paras; otherwise you'll regret it! (that's a little inside joke kids, if you don't get it, you'll just have to cry yourself to sleep, 'cuz no-one else is gonna cry for you, and you're certainly not getting any hugs for it either)...the bad news is that there seems to be a lot of you that are gonna get motorcycle-affixed dagger up the @$$#0LE. now, i know you're all thinking "but eric friggin clark, i didn't even say anything about your bike, let alone anything BAD!"-you see, that's the problem, if you can't say anything nice, don't say anything at all. your silence is an affirmation of guilt. better guard your backside, 'cuz we're coming for your collective asses...you sucky-loser-bitches.

love eric.

fuck, sorry paras. i tried posting the first time with the preview but it didn't cache my message when i went back, so i just submitted straight this time and it got fucked up. you can kill the fontsize after NIGGAZ please, thanks.

FUN FACT NIGGAZ!!!

from:
http://van.hep.uiuc.edu/van/qa/section/Electricity_and_Magnets/Magnets/20040711011415.htm

magnetic strip trouble shooting

Q:

I read the answer you gave about how magnetic strips on bank cards work, but I would like to know why, when a card won't read sucessfully, putting it inside a plastic bag before swiping it will nearly always make it work. Also, rubbing the strip on a sweater, or making it wet, or putting a piece of paper or tape over the strip also will often make it work. Is it something to do with static electricity?
mark (age )

victoria, bc canada

A:

The short answer is that I don't know, but here's some thoughts.

It's unlikely that static electricity is the key. The different procedures you name will change the static charges in very different ways, so it's hard to see why all would work if static were important.

Perhaps little rough spots on the surface interfere with the reading. Some of the procedures you mention could rub off bits of dirt and others could wash them off. Here's a wild guess about how plastic bags might work. These contain plasticizer- small molecules not well stuck to the polymer. The plasticizer can leak out- a problem for plastic food containers. It may serve to lubricate rough strips.

Here's what made me think of that. A type of copper high vacuum seal was shipped in little zip-lock bags. One of my colleagues worried that the copper might become coated with plasticizer, which could evaporate, slightly contaminating the vacuum. So he went to great lengths to clean the seals. Then they didn't work well at all. His guess that they became coated with plasticizer in the bag was right. It turned out, however, that the plasticizer was helping seal microscopic leaks at rough spots.

Mike W.


I had a problem with a magnetic strip card I had left out in the sun on my car's dashboard, and the plastic card warped and curled up on the edges. Running this card through a strip reader didn't work because the strip did not come in contact with the read head all the time. Sometimes it help if I used my hands to uncurl it a bit (very difficult to get it flat enough to read properly, and it proceeded to curl back up over time). One thing that could be happening above is that if a card is warped or bent, even just a tiny bit, it can lift off of the read-write head when read. If the card is more flexible, then it can bend back closer to its original shape when it is pulled through a narrow slot. Warming up the card a bit will make it more flexible. Many of the operations you describe above (especially rubbing it on a sweater) will warm the card up just enough to make it more flexible. I'm not sure how the plastic bag helps, but perhaps just handling the card with warm hands will help.

Tom

from:
http://www.physicsforums.com/archive/index.php/t-111660.html

02-22-2006, 01:39 PM
for anyone who was truly interested in the answer.. i found it on http://www.straightdope.com/columns/040116.html


Dear Cecil:

I've heard of this before, but didn't believe it. Now I've seen it for myself, and my
skeptical mind needs a good explanation. A lady in front of me at the supermarket swiped
her credit card but it didn't work. She tried again, didn't work. The cashier tried,
didn't work. So far, everything was proceeding scientifically. Then the cashier says, "My
friend who works at a bank taught me this." What's he do? He puts the credit card in a
plastic shopping bag, pulls the plastic tight around the card, and swipes it. Now the
part I don't get: It worked. --Tim, Newton, Massachusetts

Cecil replies:

At least the cashier's friend didn't tell him to bury the card at a crossroads at
midnight. Wacky though the plastic-bag technique seems, several of Cecil's engineering
buddies admit they've seen it work. Here's the deal. Standard bank cards use the F2F
(Aiken biphase) modulation scheme, in which flux reversals encoded in the . . . eh, too
much information. Let's just say that when you swipe the card through the reader, the
magnetized particles in its stripe generate a signal with "ticks" in it at intervals that
the machine is able to interpret as digital ones or zeros. A scratch or other defect in
the magnetic stripe can cause a spike (i.e., brief fluctuation) in the signal that a
too-sensitive reader will interpret as a tick, meaning that the encoded data will fail
the parity check (the numbers won't add up right) and the card won't work. Wrapping the
card in plastic increases the distance between the read head and the magnetic stripe,
thus reducing the strength and crispness of the signal and smoothing out anomalous
fluctuations. Behold, the card works. Worth a try, anyway--God forbid the clerk should
have to punch in the numbers by hand.

--CECIL ADAMS

Tony, sorry i missed out on recordshopping homie. what'd you pick up?

wait, I edited it, why do I have duplicate posts now? this is weird... bug! bug! :p

new, uh, famous person to drool over... (Dale Murray)

And... he played with Cuff the Duke, and the Fembots!!! y'all missed a kickass show last thursday.

and, by the way, Pink Mountaintops' Axis of Evol is an awesome album.

Yes, 'sweeet' covers it just fine. That new events calendar is disturbing as it's right there on the sidebar. I demand it to be hidden!