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Magnetic Stripe Readers, Plastic Bag Trick?

  1. Sep 13, 2007 #1
    How do the magnetic stripe readers in credit/debit equipment work? I am more curious how placing the credit card inside a plastic bag then swiping it works? I see it all of the time out in the field and I don't understand it.
  2. jcsd
  3. Sep 14, 2007 #2


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    Staff: Mentor

    Could you please describe in more detail what you are asking? Magnetic stripe readers work on the basic principle of magnetic induction:


    I have no idea what you are asking about with respect to the plastic bag -- perhaps some urban legend about spoofing magcard readers? Have you checked at snopes.com about it? Post a web link so we can see what you are asking about.
  4. Sep 14, 2007 #3
  5. Sep 14, 2007 #4
    I guess I don't understand why you would need to ask us on this forum when the link you provided explains it fairly well. I have to admit I have never heard of this trick.
  6. Sep 14, 2007 #5


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    That link explains it just about as well as anyone could. The only thing that I might add is that if the reader is contaminated with dust or something, the plastic might wipe it clean ahead of the card's passage.
    It's done quite frequently where I live.
  7. Sep 14, 2007 #6
    I didn't know of the link until berkeman asked me to post it. I then googled "credit card plastic bag" and it popped up. Image that.

    I was just curious because i see this a lot here in Florida and I never understood it. Now I'm wondering who started the trick! Cashier? or Engineer?
  8. Sep 14, 2007 #7


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    It might have started just from someone Scotch-taping a cracked card back together and discovering that it worked better than before. I seem to remember tape being used before bags.
  9. Sep 16, 2007 #8
    Just a heads up for your guys, don't scotch tape your magnetic strip. Initially it works great but when you need to re-apply some more tape because it's now worn through, you end up pulling some of the magnetic strip off, rendering your card useless. The plastic bag method works well until you get another card.
  10. Sep 16, 2007 #9


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    Good point.
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