post things that are mildly interesting
None of the others in town have these, thought it was unusual enough to share
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/ (!)
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.
Why is that insane? The entire point of an mp3 file is to be able to reproduce signals with reasonable accuracy. Seems like the signal has a frequency of around 8khz, which is very much in the range of human hearing and should be preserved by an mp3.
No, the point of MP3 is to compress audio in a lossy manner while minimizing the introduction of artifacts detectable by human hearing using psychoacoustic analysis. The coincidence that the necessary parasitic EM signal induced by speaker drivers happens to be created by a signal that doesn't suffer degradation by a relatively specific lossy compression method is remarkable.
Right, but artifacts in the ~8khz range will be detectable by human hearing. mp3s are going to be perfectly acceptable for many sounds in that frequency range... The fact that this works is evidence of that.
Plus, you know what else is lossy? Radio. If the signal is that fragile there's a good chance the locking mechanism wouldn't work in the first place.
Go actually read about MP3 compression before you continue misusing the term "lossy."
It's just going to be pulses of an 8khz signal. Why would an MP3 not encode this just fine?
Like I said before, the coincidence is what's remarkable.
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
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?
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.