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Geek toys

Back in the States, I used to buy magnets from these guys — K&J Magnetics. They sell magnets in all strengths, sizes and shapes, because you never know when you want to stick something to something else or find a screw in a leafpile. If you know what I mean. Oh, don’t question me.

Anyway, the send out *lots* of mailings and a few interesting articles, such as this one, about magnetic strip technology. How it works, how to fuck it up.

Can a neodymium magnet erase or scramble the data on a magnetic strip?

Yes. If you rub a neodymium magnet directly across the magnetic stripe, with the magnet touching the card, the data is likely to be erased or scrambled.

How strong must the magnetic field be to erase these magnetic strips?

The magnetic strip on credit cards come in two varieties. The high-coercivity ones, like a typical credit card, require a field strength of somewhere around 4,000 gauss to demagnetize. The low-coercivity ones that are often re-written, like hotel keys or gift cards, require about 300 gauss.

Worth a read, if you have the slightest interest.

I recommend these guys for all your magnet needs. And I trust that you would never, ever fuck up somebody’s credit cards without a really valid reason. You’re just too good a person.


Comment from Skandia Recluse
Time: January 8, 2014, 12:39 am

If the magnetic strip is corrupt, just key in the digits manually.

Comment from weasel tablet
Time: January 8, 2014, 2:41 am

That’s all that’s on it? The number? *crestfallen weasel*

Comment from Mitchell
Time: January 8, 2014, 3:25 am

Nice magnets. However, if you were/are pissed that the Federal Jackboots shut down Buckyballs you can still obtain such critters at Zen Magnets. Their balls are better anyway.

Comment from QuasiModo
Time: January 8, 2014, 3:34 am

Hey, cool…magnets!

Comment from LesterIII
Time: January 8, 2014, 6:06 am

More and more retailers want to swipe my drivers license lately, citing it is their new ‘policy’ but offering no good reason. I always refuse, but scrambling the strip sounds like a good preventative measure to take. Besides, having some policy-quoting-moron repeatedly attempt to do so may amuse me. Just ‘cuz, that’s why…

Comment from Deborah
Time: January 8, 2014, 1:58 pm

My grandfather, a 1st Cavalry blacksmith and gunsmith, made two magnets. They are egg-sized, rough cut chunks of scrap iron, and were stored in the kitchen towel drawer where they couldn’t harm anything. I was fascinated by these magnets and played with them my whole life, and now consider them a prized inheritance. I routinely use them to pick up spilled straight pins, because I can’t sew without making a mess.

Comment from drew458
Time: January 8, 2014, 7:14 pm

I have got to get some of those N52 magnets. Size of a gumball, yet can hold 30lbs. Sweet.

Comment from David Gillies
Time: January 8, 2014, 7:46 pm

I thought everything in the UK was chip-and-PIN these days (we’re still stuck on mag stripes in Costa Rica because we use US standards and the US is retarded when it comes to technology adoption).

I have a bunch of NIB magnets I pulled out of old hard drives. They make awesome fridge magnets although I had to write “PELIGRO” on them in permanent marker so my cleaning lady wouldn’t take the end off her finger.

Comment from Oceania
Time: January 8, 2014, 11:18 pm

Doies anyone have a design for a slurry trap using them to remove ironsands?

Comment from Scubafreak
Time: January 9, 2014, 10:18 pm

Here’s a couple of sites I like to browse for great geek gear..


Comment from AliceH
Time: January 11, 2014, 3:24 am

–That’s all that’s on it? The number? *crestfallen weasel*–

I am trying to recall what I once knew inside-out a decade (or more) ago. Credit Cards and ATM cards that comply w/ ISO standards have 3 or 4 “lines” of data in a fixed format. The data includes Name (as on front of the card) nickname (if your issuer let’s you use set one up), Card #, Expiration date, Issuing Bank ID. The format of each line is different, but some data is repeated on multiple lines — that’s so different standard machines can read/interpret row 2 or pick row 1 format or whatever.

The “3-digit Verification Number” thing printed in ink on the back of the card is NOT embossed, or encoded on the mag strip. That’s how it’s “proof” you are holding the card in your little hands and not reading off a discarded receipt or statement.

Therein ends my recollected knowledge.

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