this post was submitted on 18 Dec 2023
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things that are mildlyinteresting

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None of the others in town have these, thought it was unusual enough to share

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[–] [email protected] 54 points 11 months ago (5 children)

My local store uses these but they lock up if you bring them out to the 2nd row of parking spaces out front. It's enough to get the cart to your car, then you go to return it and it's totally locked, so everyone just shoves them into the planters in a big pile of tipped over carts instead of physically lifting the whole thing and hefting it to the cart returns to return it. The store has signs everywhere now telling people not to throw carts into the planters, and the employees know the problem, and the city has evidently complained multiple times, but district management evidently refuses to believe it's got anything to do with the cart locks and I was told by an exasperated checker that they're apparently considering getting security guards to confront people and make them return carts?? lmaooo

[–] [email protected] 11 points 11 months ago

They'd be better off getting security guards to help people carry shit to their cars.

[–] [email protected] 10 points 11 months ago (1 children)

apparently considering getting security guards to confront people and make them return carts?

Oh that's going to go down just great. How long until some rent-a-cop ends up under a car?

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[–] [email protected] 8 points 11 months ago

Oh no, not security guards! What are they gonna do, lecture me?

[–] [email protected] 5 points 11 months ago* (last edited 11 months ago)

Some Walmart GM must have a brother or something with an anti-theft wheel business because wtf?

[–] [email protected] 35 points 11 months ago (3 children)

some models use a wire in the ground that emits a low frequency radio signal... which can be also be transmitted by the speaker in a phone by simply playing these mp3 files: https://www.tmplab.org/2008/06/18/consumer-b-gone/ (!)

[–] [email protected] 27 points 11 months ago (3 children)

Of course, it’s not the sound that blocks the wheel but the electromagnetic parasites that are produced by the coil in any speaker

What the fuck am I reading?

[–] [email protected] 12 points 11 months ago

I’m not an expert in electricity and magnetism by any stretch of the imagination, but the way that I understand it is with any electrical current, there is an induced magnetic field, and vice versa. So the little parasites the article is referring to are the magnetic fields induced by the current to play the audio in the speaker. That magnetic field is the signal that triggers the antitheft device.

[–] [email protected] 9 points 11 months ago

I think they mean that the electromagnetic field generated by sending an alternating current through a coil (or just a wire) induces a current and electrical field on the conductor. I've heard the term "parasitic losses" caused by reactance but I've never heard parasite or parasitic related to generation of EM radiation.

[–] [email protected] 6 points 11 months ago (1 children)

Given the current behavior of autocorrect, I’m assuming that’s not the author’s fault. My brain has reached the point that it skips over that and just reads “currents.” I don’t know how you get from a typo for currents to become parasites, but I’ve seen even worse corrections in my writing.

[–] [email protected] 4 points 11 months ago

My guess would be "interference" that got autocorrected.

[–] [email protected] 9 points 11 months ago (9 children)

It's absolutely insane that a speaker coil works as an antenna in this case, but perhaps even more insane that the signal survives mp3 compression.

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[–] [email protected] 8 points 11 months ago

Can you imagine what would happen if someone went into a crowded store with a device playing this. A short loop through the isles and til queues would wreak havoc.

Sounds like a basis for a fantastic prank.

[–] [email protected] 21 points 11 months ago (1 children)

Those things have been around for a long time.

[–] [email protected] 5 points 11 months ago (1 children)

I remember them being introduced at least 15 years ago. My manager at the time would wait and laugh at people trying to take them past the parking lot. She was a really miserable person.

[–] [email protected] 5 points 11 months ago (1 children)

I wouldn't be surprised if they don't even work anymore just because of how long they've been around.

I've never bothered to try it recently though.

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[–] [email protected] 18 points 11 months ago (2 children)

Many grocery stores in my area have these wheel locks. If I recall from college, if you took the cart out of the parking lot by carrying it over the plant beds, the lock would not engage.

[–] [email protected] 11 points 11 months ago* (last edited 11 months ago)

These most likely lock from a small electric loop around the lot triggering an internal magnet, so y'all found a gap in the loop.

Nice hacking.

[–] [email protected] 7 points 11 months ago

You can just lift the wheel about a foot off of the ground when passing the loop that engages the lock. Much easier.

[–] [email protected] 17 points 11 months ago (2 children)

The safeway near my apartment is so ghetto the wheels lock as soon as you leave the store exit. You have to take everything in one trip or wait for your car to pull around to load.

[–] [email protected] 29 points 11 months ago (3 children)

I'm pretty stubborn. I'd probably just drag it across the parking lot like a neanderthal and let the asphalt grind flat spots onto the wheels.

[–] [email protected] 9 points 11 months ago (1 children)

The ones I've seen usually only lock one wheel, maybe two on a side. So you can wheelie the carts just fine.

[–] [email protected] 4 points 11 months ago

Half the carts I’ve ever used have a busted wheel anyway lol.

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[–] [email protected] 16 points 11 months ago

Must be working. I haven't seen a cart on cinder blocks in a while.

[–] [email protected] 15 points 11 months ago (1 children)

Pretty much every store in my city has these, didn't realize they weren't a thing everywhere.

[–] [email protected] 14 points 11 months ago (4 children)

It's a litmus test for what type of place you live in. I guess you just found out where yours lands.

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[–] [email protected] 13 points 11 months ago (3 children)

If places where I am in the UK don't have this, they have a coin return on them.

[–] [email protected] 7 points 11 months ago (2 children)

25¢ for a shopping cart is a pretty good deal if you think about it

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[–] [email protected] 7 points 11 months ago (1 children)

(at least in poland) people usually just leave their coins in the carts, I've never had to put my own coin in there

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[–] [email protected] 5 points 11 months ago (1 children)

If they don't, they'll be fishing them out of the canal.

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[–] [email protected] 13 points 11 months ago (1 children)

Bubbles would be really disappointed

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[–] [email protected] 12 points 11 months ago (1 children)

for the small price of a hex head wrench, you too can be the owner of a proud new Walmart shopping cart…. I wonder if walmart sells replacement wheels.

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[–] [email protected] 8 points 11 months ago (1 children)

It depends on the exact location of the store... pretty common in urban areas. Makes sense as carts cost hundreds of dollars and people will just walk off with them and ditch them once they get home, or of course homeless people often take them and use them for a while. First time I saw this was in Uptown Minneapolis about 20 years ago. Seen them all over since then. I found a brand new Safeway cart in the alley behind my house and was 'great!'. I wheeled it into my yard and then wondered wtf I was planning to do with it exactly. Apparently, if you call them they have someone who goes around picking up carts, so I let them know and someone from the store came and got it.

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[–] [email protected] 7 points 11 months ago

these are pretty common at supercenters in Chicagoland

[–] [email protected] 5 points 11 months ago (2 children)

I've only ever seen these in malls so you don't take the carts to other places in the mall. Do they really use these for carts going out to the parking lot too? How're you supposed to get your groceries out of the store?

[–] [email protected] 7 points 11 months ago (1 children)

My local Kroger has these, the perimeter extends all around the parking lot.

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[–] [email protected] 5 points 11 months ago

There is a walmart locally that has these or used to have them. Theirs were easy enough to disable.

[–] [email protected] 5 points 11 months ago

We've had these in the UK for a long time, mainly to stop people carting shopping home using the trolley and then abandoning it.

[–] [email protected] 4 points 11 months ago (1 children)

Was I the only one who thought the wheel was laying on the ground?

[–] [email protected] 5 points 11 months ago

Yes. You are the only one.

[–] [email protected] 4 points 11 months ago (3 children)

Do you know how it works? Doesn't seem to be electronic or so... Perhaps mechanical magnet based or so

[–] [email protected] 15 points 11 months ago* (last edited 11 months ago)

There's a talk at DEFCON on YouTube about hacking them. Great way to see how it works.

https://www.youtube.com/watch?v=iprBprAFXCk

[–] [email protected] 10 points 11 months ago

https://www.youtube.com/watch?v=-QKcprQD0zc

It's a fancier version of the electric dog collars. If you go over a perimeter line it'll turn on a parking brake for that one wheel.

[–] [email protected] 6 points 11 months ago (2 children)

Probably an electrical fence type deal. When the signal gets too weak the pins pop out to prevent the wheel from rotating. Didn't park near the edge of the property to test it lol

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