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After a year of watching other people lock up carts anytime, I desided,I want one. Two hours later, James Bond's Cart Locker was born.

Step 1: Step 1: the Case

To Make your case to hold the electronics, Take a normal bic pen(shown in photo) and remove and save everything.

Step 2: Electronics

Take a pair of ear buds and a telescopic antenna. Cut the headphone jack off of the ear buds, leaving 1 inch of wire. Strip ONLY ONE wire so there is 1cm of bare wire. Solder or wrap the wire to connect it to the antenna. Cover this connection with electrical tape.

Step 3: Connect It All Together

Slide your assembled electronics in the pen until the head jack wont go any further. Tape the jack so that it stays there. Secure the antenna so that it stays in place but will telescope.

Step 4: The Final Touch

To Finish this up you can;
1.) Spray paint
2.) Cap the head phone jack with a piece of drinking straw
3.) Add anything else to make it look exactly like a normal pen.


P.S. if you have any Ideas or comments please post them.

Step 5: Making It Work

Download the joke file and add it to your MP3 player or ipod. Plug the pen's jack into the player's port and extend antenna. Play the file. Any cart with this tech will lock up. Not all carts do this. Stop playing to unlock.

If you can't download it, It's a 7800hz pulse tone. Search Google for " NCH Tone Generator. Play around with it for awhile and you'll get it right.

Step 6: Enjoy

Enjoy your new cart locker and have fun.

P.S. Also post if my instructions could be clairified
Telescopic antenna? Wath is that and where can i find one
what is a cart?
Shopping cart, buggy, see picture.
and how is is suppose to lock??? like the wheels or what
nice picture
did you actually get this to work? if so how did you connect the ant.
I can't tell you the fancy reason why, but it doesn't work, yes I built it..l
i hate to be the bearer of bad news, i like the concept. However the design has many flaws. 1) There is no way that this is going to send out the 7800 mHz Signal. there must be some sort of magnetic wire wrapped around this. also where are the terminals on the headphone jack connected to?
1 = many flaws? que?<br/>
What?
This will NOT work, its exactly the same as a wire going from the positive of the speaker to the ground, no matter where you solder the wires on the antenna! And before you try to say I didn't read it, I read it multiple times.
ok i hope my way works. - i took an old clock radio and cut off the radio antenna (it was a wire antenna, not the collapsible metal tubes) I took the headphone connector from an old mini ipod speaker and took off 2 of the 3 leads, because you only need one. I stripped both wires and connected them, then put some tape over it to hold them together, and a little more tape just to reinforce any weak areas. I took the antenna (it still has the rubber coating) and wrapped it around a piece of foam except for an inch or so at each end. then I took an old sd card case, cut a hole in it, and put everything inside and glued the headphone jack through the hole. I only had gorilla glue on hand so I hope it doesnt expand too much and not allow me to make the connection with my ipod. if so I need to scrape some off with a razor. its drying right now, I really hope this works (I'm the kind of person who used to carry a universal tv remote with him all the time to mess with people)
whats a cart locker?
some shopping carts have a special device that locks them if someone tries to remove them from a certain area, so that no one can steal them
how does this work? it makes no sense to me
yea
well it recieves input from the headphone jack, which normally would be used in a speaker. but instead the electrical pulses are sent through the antenna to the cart.
no heres what you do get a job as a radio dj and find a store with locking carts. see if they play music in the store /find what radio statioin it is then play the sound file or whatever it is on the station, mayhem in the whole store!. plus you get fired from the job for "accidentally' playing a weird song hehe so you dont have to quit from that crappy job.
my <a rel="nofollow" href="http://reviews.cnet.com/mp3-players/lexar-ldp-600-512mb/4505-6490_7-31266276.html">lexar LDP 600</a> has a built in tuneable radio transmitter ,it uses the headphones for ant as well a small telescoping ant that plugs in to the headphone jack <br/>Is this the missing link for this build? <br/>
?
the mp3 player has a fm transmiter built in and can play the file lol as well as transmit it .how does the cart get the signal?from a fm transmision?at a set ferq?with the signal modulated to that sound?
Do this with an FM pen, so you'd have an excuse for an extendable antenna... THEN, use an FM modulator on an ipod in your pocket set to auto-repeat.
Reading all the other instructables on this and now knowing the theory, I can tell you that this instructable will do nothing but wreck your mp3 player. These shopping carts detect changing magnetic fields, and if the frequency is right they respond by locking up. An antenna cannot produce a better magnetic field than a piece of wire, and even then it is a horrible field. Playing the sound file (if that is even right, which I doubt) with regular headphones is more likely to work than what is shown in this instructable, because as we all know, speakers work by vibrating a diaphragm with a magnetic field.
unless you mistakenly short circuit the jack this has no effect on the mp3 player.
You could put in an amp and coil. Real simple. Might need a bigger pen...
haha, That would be one helluva coil. :)
I got around to calculating, that. You would need a few thousand feet!
Actually, the signal is an <em>electro</em>magnetic field, kinda like a radio emitter except not using standard radio frequencies. <br/><br/>Based on some of the other instructables, the signal seems to be a 7.8kHz pulse, which is smack in the audible range of frequencies (or VLF - Very Low Frequency - in the EM spectrum), so it can easily be captured on an mp3 player.<br/><br/>All that's needed is some sort of antenna to transmit the signal. For a VLF signal like this, a telescopic antenna isn't ideal, but it's better than nothing. Remember - the store probably just uses a long wire buried around the edges of the parking lot. You may want to put a resistor in series with the antenna to avoid shorting the output amp.<br/><br/>Don't know whether a speaker would work better - speaker are designed to transduce an electrical signal to a sound signal, not to emit a strong electromagnetic field. A large induction coil such as used in some of the other instructables would work much better. <br/>
speaker would not work b/c, as you stated, it's for transducing electrical signals into a sound signal. a sound wave is nothing like an electromagnetic wave. Sound waves have to do with pressure and the pressure of the air. EM waves have to do with magnetic fields. if you could unlock carts with sound, one could sing into a wheel (at the right pitch of course) to lock/unlock it
ok.. did a little research.. guess there are some carts... that happen to lock the wheels if you take the cart to far away from the base station. This instructable basically either blocks the signal its trying to receive... or its magic... i guess.
The opposite actually, the project creates the same signal that causes the wheels to lock up
Ok I'm just going to say it. FAKE! I quote: "C:\Documents and Settings\Ryan Seals\My Documents\My Music\iTunes\iTunes Music\Use coil pen\Unknown Album\CART LOCKUP JOKE FILE.wav" Note the file name? I guess I should be saying JOKE. Beyond that, though, there is the simple fact that the current design wouldn't actually transmit anything. But nice try :) -Zaen
See ry25920's Jun 14, 2008. 5:58 PM post for explaination of the joke name. It's a good idea to read all existing posts to see if what you want to post about has already been covered.
you obviously missed the entire point of this instructable. the reason is is called a cart lockup joke is because you use it as a JOKE to LOCK UP CARTS in your local target or wal-marts. not because the file itself is a joke.
C:\Documents and Settings\Ryan Seals\My Documents\My Music\iTunes\iTunes Music\Use coil pen\Unknown Album\CART LOCKUP JOKE FILE.wav Notice where it says JOKE FILE. This wont work. Please don't waste your time.
I named it joke file because this instructable is used to play a joke on someone. I don't see a problem with naming a file that plays a joke on someone, "joke file". This will work, but it won't if you don't build it right.
well it IS the actual cart locker frequency, but I still wont believe you until you post a vid of SEVERAL different people getting their cart locked.
i think i'm going to just download the file later and play it through my ipod because i'm lazy =p<br/><br/>but, does the volume effect the magnetic field power such as higher sound level equals better chance or better radius of locking up?<br/>
any1 got this working ???
Have you actually tried this? An antenna is nothing more than a long piece of wire, its just more rigid, looks nice, and is sometimes extendable. If you solder two wires to an antenna its the same as soldering the two wires together, meaning you will short the mp3 amp. I'm not saying this doesn't work, I would just like to know the theory before I wreck my ipod.
Agreed. Everything I know says this will do nothing more than wreck your mp3 player. I wouldn't even try this on the 256MB Coby I picked up for 5 bucks. I have seen working devices that lock cart wheels, but they're complex electronic devices with PCB's, microcontrollers, and code that generates pulsed waves at specific frequencies. I'd say I'd believe it if a video got posted, but I can think of several ways to fake that on camera. I'm going to flag this one and hope that one of the senior members here with more electronic experience can give an authoritative "This will not work because..." or maybe just remove it. If people try stuff like this and nuke their iPod, we stand to lose a great deal of trust in the community, and that's not a risk I'm wiling to take!
Or, you could just accept reality and deal with the fact that a simple coil that can do what a complicated device can.
Look, if you don't want to wreck your ipod, don't do it.
If you read, you physical can't short your pod because only one connection is there.
I have edited this page so can you please re-read this and post your comments
Thank you, I almost over looked that. Please re-read it and you will find that problem is fixed
Any idea as to the length of the pulse and the time in between each one?
I think I just found a use for my next Altoids tin.
what do you mean "lock up carts"? what carts? where can these carts be found?! i get the impression we may not have them in Australia... i.e. include in your instructable what this item actually does...
In the USA shopping carts are often taken far from the store, spawning a new industry: shopping cart retrieval... people that drive around finding 'lost' shopping carts and hauling them back to the store, which pays them. To prevent these carts from wandering off, some stores have installed a system that locks up the wheels of the cart or makes the carts only turn in circles etc., when the cart goes beyond a certain limit. This instruct is to make an emitter that signals the carts to lock their wheels or turn in circles, WITHOUT them going beyond the store's 'certain limit'... in other words, to make the carts lock up while inside the store, or wherever they are. Might be nice to make one that would UNLOCK the cart I am using so I can take it all the way to my car instead of just within 50 ft of the store. One store that uses these is the 99 cent store in Granada Hills California, for instance. If my 99 cent store cart locks up in the store, I'll come find you and say hello.

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Bio: To me, if someone calls me a nerd, I take it as a compliment. I am a nerd. If someone laughs at me for being ... More »
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