Why do magnetic business cards not act like N&S pole magnets ?

self | February 11, 2013 | knarf

[knarf]

Playin' around with a couple of 'em and they don't do a "repel" thing

[knarf]

wonderin'

[Jonty30]

It could be that they are magnetized too weakly to really do anything.

[Da Coyote]

The card’s magnetized portion has many small N/S orientations...arranged in a specific manner so as to 1) generate a “clock” signal when the card is swiped - so as to allow the reader to correctly detect and decode the 2) actual binary data contained on the strip.

These individual portions of N/S orientation appear almost random from any distance greater than a mm or so, and therefore cancel out.

[Gaffer]

I think I looked that up one time years ago after noticing he same thing. IIRC, the magnetic material is contiguous, but I believe stripes are magnetized in aleternating N/S strips. IOW not one big magnet but striped magnet strips that alternate and separated just enough......hope this is right and helps.

[Yo-Yo]

The big black rubber backing is magnetized with strips going N-S, S-N, N-S, S-N, etc.

[1rudeboy]

Short answer? Because Sandy Hook.

[BitWielder1]

There are hundreds of tiny, weak ones in the strip, oriented this way or that to form a binary code.
Too weak to pick anything up. Strong enough to be detected by a reader.

[SkyDancer]

‘Cuz the poles go in and out of the card rather than parallel to the card? It does kinda work if you flip the cards end to end. Then, what do I know .... LOL

[Gaffer]

I think knarf is talking about essential refrigerator type magnet business cards, not data-swipe cards.

[Responsibility2nd]

 

 

 

 

 

 

 

(Too much time on your hands)

[knarf]

Yep .. refrigerator magnets .. and .. after posting, I discovered if I put two cards togther magnet to magnet, and slide them, there is a definite 'washboard' effect which aligns with (pun intended) the NS/SN/NS/SN etc. explanation.

Interesting

If we think hard enough about this, maybe we can develope a perpetual motion mation.

(I AM kidding ... but it IS interesting)

[Paladin2]

I've been looking and looking for the magnetic monopole I lost years ago.

Thanks for finding it.

[Scrambler Bob]

I pulled two off my tool chest, to experiment.

Mine stick together, then when moved slightly, they repel, and seek to move back or forward to the next ‘sticky’ position.

So the attract-repel feature is still there, but the cards are not magnitized as a single magnet with a N-S at each end.

The N-S must be in a pattern (such as stripes) on the card. The card is a bunch of iron particles embedded in a non-magnetic plastic-like material.

Next step would be to seek info from the Google info god, but I’ll leave that for the next Nobel Peace Prize seeker.

[knarf]

There ARE advantages to .. I don't HAVE to go to work.

Puttin' some else's kids through college never appealed to me.

[Gaffer]

BS

[The Free Engineer]

That is what I thought too.

So I am looking at a couple and offer three observations:

1. They do stick together.

2. You can slide one across the other smoothly in the horizontal direction.

3. You cannot slide one across the other smoothly in the vertical direction. There is a "jump" from one position to another at about 1/8 inch increments. In-between those positions, the cards are repelling one another.

So I must conclude that the surface is magnetized like this:

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[cripplecreek]

Well grasshopper, the wisdom you seek can only be found upon a barstool.



Now I'm off to discover why the microwave tray turns one way till I turn the oven off and on again when the tray turns the other way.

[Gaffer]

Just like I said.

[Olog-hai]

Did you try floating them in a bowl of water and see if it points north?

[vet7279]

If we could only get congress to put this much effort into the debt, we might just get somewhere... :)