Portable Shopping Cart Locking Force Field OF DOOM

Introduction: Portable Shopping Cart Locking Force Field OF DOOM

About: My name is Joe. I enjoy long walks on the beach, pina colladas, getting caught in the rain, playing with dead things, playing with fire, hacking, programming, reverse engineering and blowing stuff up. my are...

Have you ever been annoyed or even injured by evil sentient shopping cart attacks? well, now you can shop in safety! this belt will stop any hostile shopping cart in it's tracks if it comes within five feet of you! No more bruised ankles! no more threat of cart insurrection!
This life-saving device works by emmiting intense electromagnetic radiation that confuses the shopping cart and makes it think it has reached it's boundaries causing it to lock it's wheels in fear. don't delay, Build one NOW!

This is a proof-of-concept for educational purposes only, and may be illegal in some areas. this device also has the potential to really piss off store managers, so please use with discretion. i take no responsibility for the actions of anyone reading this.

You're going to need:
1 db9 female plug
1 db9 male plug
3 feet (roughly) of cat5 cable (or a serial cable)
1 headphone plug/wire
1 mp3 player
1 laptop or good quality recorder

Step 1: Make the Belt...

First, cut a length of cat5 cable so it is long enouth to wrap around your waist (you can make it wrap around twice, if you want, but i didn't), but make it loose so you can work with it.

next get the db9 plugs, headphone plug and your soldering iron.
connect the cat5 cable's wires to the db9 plugs with the following pinouts:

pin: | wire color:
1 Green stripe
2 solid Green
3 Blue stripe
4 solid Orange
5 Headphone jack
6 Brown stripe
7 solid Blue
8 Orange stripe
9 Not connected
the extra brown wire goes to the headphone jack

pin: | wire color:
1 Solid green
2 solid Blue
3 Orange stripe
4 solid Brown
5 Brown stripe
6 Green stripe
7 Blue stripe
8 solid Orange
9 Not connected

Step 2: Go to the Store!

For this step you'll need either a laptop with recording software or a really good voice recorder.
Go to the store and find the cart boundaries. they'll probably be marked with a yellow line. once you found the yellow painted line, look for a thin, black line running parallel. that black line is the actual boundary, beneath it lies a wire emitting the cart-killing signal.

connect the belt to your laptop or voice recorder... actually if you have a telephone mic, use that instead. (it's those little suction cup things you put on the phone. it's just a coil of wire) or, if you're cheap use a solenoid attached to a headphone jack. unmute the microphone in your laptop's sound mixer and turn the volume way up. position the coil/pickup/whatever over the wire until you hear a signal. at the sprawl-mart i went to, the sound was a short chirping sound every half second.
when you hear the sound, record it with your favorite sound recording program. make sure to record it at at least 44100 hz at 16bit. DO NOT SAVE IT AS MP3. save it as an uncompressed wav file.

using your sound editor, do a little noise reduction (if any is needed) and increase the volume.
i lied, you can save it as mp3, but remember, it's a lossy format, meaning you will loose data, so use at least 128kbps and turn off any filters.

once the file is satisfactory, put it on your mp3 player (or whatever. i used a program on my pda-phone)

Step 3: Going In!

It's time to try it out!
put the belt on, and wear a shirt long enough to cover it. plug the belt in to the mp3 player, crank up the volume and put it on repeat. i recomend putting the mp3 player in your pocket. test the range by moving close to a cart until it stops. if they stop, awesome! if they don't, GO OUTSIDE then check for shorts (don't do it in the store!), if there aren't any, your mp3 player isn't loud enough.

Step 4: The Missing Page!!!

Coming soon:
the shopping cart force field OF DOOM version 2.0
Now with amplification, you can keep the hostile sentient shopping carts up to fifteen feet away! Stay tuned!

I haven't had time to solder up an amplifier circuit, yet. (actually, i did, it just doesn't work) if you've just got to have one now, try using a battery powered amplified speaker, and replace the speaker with the belt.



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    149 Discussions

    the shopping carts will hate you :)

    What country is this from? I'm in the US and I've only heard preposterous theories about self braking shopping carts.

    2 replies

    The shopping carts at HEB in the low-income areas of Houston, TX lock up on you! It was really surprising to push one really fast across the boundary and watch it fall over. haha

    i am in us and i have had a shopping cart lock up on me. look for a weird device on one of the wheels it looks innocent but it will brake it fast!

    i just built one of these, and im so excited to try it i can hardly breathe... oh well. Amplifiers are very easy, just break open a tv and find an IC with only one side covered in pins, probably starts with "AN" (the # on the front) and look up the schematics online. I built one of these, and it just took an hour for a 3w amp. not amazing, but same principal i guess... T-elospathic

    15 replies

    cool, DON'T GET CAUGHT! also, i'm not going anywhere near the very high voltage innards of a cathode ray tv. i've seen a screwdriver weld itself to a tv amid pretty spaks and a very loud crack. i'll just destroy a stereo for the parts.

    I Agree, and handling the Cathode Ray Tube in the wrong way and you drop it, it may EXPLOED!! If your going to use parts from a older tv always, always remove the thick red wire that looks like a suction cup (its about half way down the Cathode tube(towards the part you watch CSI: MIAMI on( by removing this wire you let the gases inside the tube to escape))) also for added safety remove the wires at the small end of the tube. And always remember UNPLUG IT FIRST BEFORE OPENING THE CASE!!!

    removing the tht (suction cup) will not cause any gasses to escape, in fact, the tube is a vacuum and there is no gas in there. If I had listened to your advice, i'd be in the hospital with arterial fibrelation!

    well you would if u either left it plugged in or opened it right away cuz the CRT can still hold energy after sitting unplugged for a few days, 30+ days should be enough time for the power to drain off.

    oh and my dad told me there was gases in a CRT, and my dad is known for being incorrect 80% of the time

    The CRT is a vacuum. It may not be a perfect vacuum, because of manufacturing error, but it is not filled with gases. Sorry daddy, but this is part of that 80%!

    The one that shocked me was unplugged ~5 minutes before electrically assaulting me. The CRT does not hold energy, and the amount of capacitance that the flyback has is likely lower than 5 pF. That's hardly anything. What holds charge are the capacitors that supply/buffer the flyback circuit.

    This is a long thread. This is awesome.

    I took apart a TV and i didn't get shocked. There are 3 facts I found:
    1. The CRT is a vacuum, it is also known as a vacuum tube.
    2. It is not filled with gasses. Why would they even think of putting neon or another noble gas inside a TV?
    3. TVs won't shock you as long as they are old and aren't plugged in and all the capacitors are empty.

    Sorry bioerror it's 3 against 1...

    The red wire is a BAD thing to play with. unless you like 15-30kV coursing through your body, don't touch the suction cup. All I am saying is that TVs are a good place to find these audio amp ICs, because they are small and self contained. TVs aren't scary, just the red wire should not be messed with unless you discharge the capacitors. Simply put, just don't touch the Red Wire .

    all you have to do is stick a grounged piece of metal under the suction cup to discharge the tobe and anything left in the flyback. the red wire carries high voltage while in operation but if you discharge the tube and board, nothing will happen if you touch it. I have taken apart several crt moniters and have not seen any person that has been electrocuted after they discahrged the tht. Use insulated pliers to push a peice of metal that is grounded under the suction cup. you could also use a grounded screw driver. It is totally safe after discharge... you did unplug the cord from the wall... right?

    It's nice to see someone who isn't afraid of Tvs... Like he says, all you have to do is ground a screwdriver via a wire going into the ground hole of an electrical wall socket, etc. and poke it under the suction cup and touch the piece of metal under it. Cathode Ray Tubes really aren't much to be afraid of.

    exactly, im 13 and pulled apart many in my short life (without getting the slightest shock :) )

    Try shooting a discharged crt with an air rifle - Just do it from a distance and put something to collect the glass eg thick tarp and 5 sided box made of concrete slabs. IMPLOSION!

    exactly. tv sets are not scary at all. If you know what your doing and you take the procaution you will not get a lethal dose of electricity. Take caution and stay away from things unless you are properly insulated of you have discharged the electricity and the inside of the tv will not pose any threat.

    Even still, I believe the lethal amount of electricity across your heart is 7 mA, and as I have been shocked by the flyback on a crt before, I am still here to say that it is not a lethal amount. On the inside of the monitor housing somewhere it will say how much voltage goes through that wire, and what current it is pushed at.

    Google how to discharge a CRT safely - theres also a few instructables about it. Also don't try to remove the suction cup unless you 1) know what you're doing and 2) Have already discharged the CRT. Having your hand stuck on to a glass tube that is electrocuting you (Unlikely, but meh) doesn't sound too fun.