Quick wallet hack adds pickpocket alarm

Recently there were a bunch of videos going around the net about some of the greatest pickpockets in the world. Simply put, if they wanted something you had, they were going to take it and you probably wouldn’t notice. I’ve always kept my wallet in my front pocket, and usually with my hand on it, but they even showed them getting around that in the video (you can’t always be vigilant).

I had the idea to make some kind of alarm that would go off if anyone but me removed the wallet from my pocket. A quick google search revealed tons of wallet alarms, but I noticed that they all had a credit card form factor(that’s good) and would make noise when exposed to light(that’s bad). This represents a problem since the pickpockets in the videos tended not to open the wallets till later at another location. I needed something that would make noise as it was removed from my pocket. Most importantly, I needed the alarm to be located inside the wallet. This immediately makes the wallet undesirable and will hopefully make someone drop it like hot coals.

I happened to have a few little magnetic window alarms sitting around. They’re just a loud buzzer with a magnetic reed switch.  After holding one up to my poor fat old neglected wallet, I saw that the alarm was roughly the same thickness as all the old business cards I should’ve cleaned out of my wallet anyway.

I promptly tore the alarm apart and started planning how I was going to slim it down as much as possible.  Most of the thickness is from the case, the batteries would be the next biggest contributor.  After destroying the buzzer from one by trying to pry it from its plastic enclosure, I decided to leave the buzzer and simply live with the thickness. After all, if the prototype worked well, I could design something in a credit card form factor later. That is, if my attention span were long enough to do a thing like that.

The only real modification I made to the alarm itself was to un solder the reed switch and relocate it to the very end of the whole mess. This would allow it to be at the “spine” of the wallet and keep the power switch at the opening for easy access. The rest was simply cutting away as much bulk as possible and hot gluing things together.

It actually works exactly as expected. There are two choices for the alarm, a single chime when removed, or a constant alarm. The only big upgrade that I would suggest would be a stronger magnet so it wouldn’t need to be aligned perfectly.

Comments

  1. Dr. DFTBA says:

    What about if they drink a Philther of Pickpocketing with a skill of 100?

    • Luke says:

      It would effectively guarantee the odds that your rogue character can physically extract the wallet without alerting the character being robbed, but a second 1d12 check is introduced that depends on your Disarm Device skill being up to snuff, with an added 1d8 penalty subtracted if you didn’t foresee the alarm using your Trapfinding skill.

      A silence effect will obviate the need for an alarm check and give you time to use Disarm Device at your leisure, so having a bard in your party is useful here. However, be sure the general vicinity around the target to be pickpocketed is relatively quiet, or the sudden deadening of sound may itself alert the character, and the GM could choose to do some really bad things to you for that.

      • Mental2k says:

        That may be my favourite comment on HaD and I don’t even play D&D!

        • plugh says:

          Don’t worry, Luke doesn’t play D&D either. d12s are only used for large weapon damage rolls, not for skill checks, which are on a d20. Penalties are flat rate increases to the skill check, not random. This looks like a DC 15 skill check to pick the pocket, DC 12 search check to find the trap, and a DC 10 disable device.

          • gabe says:

            why don’t you just attach a small bell on your wallet?

          • Luke says:

            How do you know I don’t use a modified ruleset? Hmm?

            What if the action in question is minor, so I’m going with a die that has better odds for convenience’s sake?

            And what if I want to introduce an element of variability to my penalties, because flat rates are boring and we need to keep the one guy who majored in statistics on his toes? Did you think of that?

            Well, that’s okay. I actually don’t play D&D. And the joke in my prior comment flew high above your head, so joke’s on you! Oh snap!

  2. Steve says:

    Good hack Caleb, I like it, start big and dirty, plan better implementations later, make procrastination logo later.

  3. Yet says:

    You’ll have lots of fun going through airport security with that.

  4. Hu?! Also say goodbye to all your magnetic striped and chipset based cards in your wallet! Maybe in US you have different kind of cards that don’t get erased when near a magnet?

    • MrXavia says:

      In the UK its all chip n pin now, so magnetic strips are pretty much redundant, I think the only magnetic strip I use will be for older ATM’s

    • Whatnot says:

      That is indeed a general issue with magnet-based stuff, you cannot keep them on you without at some point getting an issue.

      Oh and for my personal critique on this project: don’t hotglue something you keep in your backpocket, epoxy that shit or you’ll get a pocket that is fused close at some point.

  5. Paul says:

    That is very cool. I’m tempted to make one as well. What would be even more interesting, though, would be to have the wallet give the thief an electric shock.

  6. Jorge says:

    What about the credit cards being deleted by the magnet?

    • Caleb Kraft says:

      I wonder if that is actually a concern. I kind of doubt it is, but then again, they are magnetic.

      • Erik says:

        What’s going to erase your cards is a strong magnetic field that is moving a lot.

        So if your wallet is a tight fit in your pocket, and the magnet is similarly immobile relative to the wallet, you’ll probably be fine. But if things move around a lot in there as you shift and sit and stand, or if you pull out your wallet a lot, you could be in trouble.

        • Sven says:

          That is in fact wrong, a strong static field is enough, such as a neodymium magnet. We tested this using a few outdated student cards and a card reader once. A sufficiently strong 3x15x30mm magnet caused data errors on the card from 10mm, or there about.

          • Cricri says:

            But Caleb’s magnet is a lot smaller. Plus most cards over here rely on their chip more than the magnetic strip.

        • perroloco says:

          I’ve tested by myself several times, you don’t need a really strong magnet to delete/damage a magnetic card, neither you need to move it very much.

    • MrX says:

      I don’t see a magnetic credit card for a while.. They are all chip-based around here.

      • perroloco says:

        Well, chip-only cards are becoming very popular, but you still have other magnetic cards: Gym access, some hotels, some supermarket discount cards (here in spain), underground tickets, and many others.

    • Codongolev says:

      My father has a billfold with magnetic closure that he keeps his credit cards in, and they still work. I think the only thing you have to worry about in that respect is reprogrammable cards, like hotel keys.

  7. Christian says:

    Maybe it could be easily smaller by using one of those sound-birthday-cards in combination with the magnet switch?

  8. 8complex says:

    Just put it in your front pocket… it’s better for your back anyways.

    I prefer one of these — http://www.raggededgeproducts.com/index.php?main_page=product_info&cPath=68_154&products_id=378

    • Caleb Kraft says:

      I usually do. The video of pickpockets showed them getting around that too.

    • Sven says:

      I used to have my wallet in the back pocket. I also used to have severe back problems. Now i don’t have either.

      • Tom says:

        I’ve got friends that do massage therapy, they all say back pocket wallet is a big no no, when you sit down it messes up the alignment of your hips and lower back.

        • ehrichweiss says:

          It’s true. I discovered this about 15 years ago. It really goofed with my lower back. Moved it to the front pocket and everything’s fine.

          • J says:

            maybe you guys just need thinner wallets?

          • andarb says:

            An old boss of mine was a pickpocket’s dream but never got caught – he would carry around a few hundred in small bills aside from cards. Had back problems intermittently. I recommended that he switch to a different kind of wallet or carry it in the front pocket… and his back pain corrected itself. His wallet looked something like an overstuffed Subway sandwich.

  9. Erik says:

    The easy accessability of the on/off switch would worry me. You could probably hide that comepletely if you were willing to wear a ring with a strong magnet; the field from the ring would keep the alarm quiet while the wallet was in that hand….

  10. polossatik says:

    I just use a http://www.thisnext.com/item/B7F5C2A2/Sliding-business-card-holder for the few cards i need (visa, debet, heath ensurance , gov ID, driving license).
    It’s metal so you hear it drop and it does not look like wallet :) .
    I keep money (bills) loose in my pocket and ditch every evening any coins in a whiskey tube (pay 97% electronic anyway).
    Really don’t see why people carry everyday everywhere fat wallets with things you don’t need around.

  11. Slipster says:

    I’m married. There’s nothing in my wallet.

  12. Bob says:

    Musical greeting card + reed switch + magnet = much smaller

  13. Sven says:

    What about using one of those radio based “don’t forget your luggage”-devices? The transmitter is about 5mm thick by 30mm diameter, and the receiver could probably be stripped down quite a lot.

    That would eliminate the magnet, and also let you set things up so that the wallet wouldn’t make sounds until it was a meter away from you or so.

  14. flink says:

    A flat, 2oz square of semtex on a five second timer is more effective at stopping pickpockets.

  15. mfsamuel says:

    Rather than demagnetize all your cards, how about a photo-diode that closes a loop to a tone generator circuit. Should be able to get that with a coin cell into a credit card sized package.

  16. kj6epl says:

    For those worried about the magnet erasing cards, what about using phototransitors? It might not be as reliable as the magnet, but if it’s daytime, it would work. I would recommend at least 2: one on the top and one on the bottom, as the odds are that the pickpocket’s hand won’t cover them both. If you really wanted to, you could probably use 4: one on each corner.

  17. popman says:

    I was expecting the alarm to be triggered when a pin is removed.

    With the other end of the pin attached to a spring-clip you can release from your pocket lining whenever you want to use the wallet.

  18. ddierick says:

    It would be nice to incorporate a tiny taser instead of a sonic alarm.

  19. fartface says:

    Simplest solution is a short cable to the wallet that hooks around a button inside the pocket. you can remove the wallet to just out of the pocket, but any further and it will not release.

    • DosX says:

      In trinidad they cut purses and backpacks from under your arm as they pass, its a relatively quick process for the seasoned. I reckon a smart @$$ would walk with a knife to slice that cable…unless cable needs a wire cutter or something of a considerably annoying size to cut it with

  20. The volume can be reduce by using the musical cards hardware.

  21. anglo says:

    metal threads on the wallets exterior , coming from a business card sized supercap , rfid setup detecting the wallets presence/absence., and the pickpocket will BE the alarm sound. :-)

  22. Ren says:

    Don’t forget to use a decoy wallet. The one that has the slip of paper that says,
    Damn you’re good, but not good enough!

    • Sven says:

      “Don’t look around, you might see the cop behind you.”
      or
      “You might have time to avoid the baseball bat moving towards your head if you move now.”

    • targetdrone says:

      My small decoy wallet has enough cash in the local currency for the day’s outing, and nothing else. I hate having to expose my real wallet in a public space.

      In Amsterdam last spring, my wife and I were in a cheese shop, which was a fairly narrow store that was empty except for the shopkeeper, us, and one other guy who did not look like a tourist shopping for overpriced cheese. I had my hand in my pocket, wrapped around my wallet, yet this guy kept trying to maneuver around to get beside and behind me. In that tiny space, such an obvious move was impractical, and the results were almost comical. I finally got sick of him, so I stared straight at him and asked, “really? You have to stand next to me?” I don’t know if he understood English, but he sure got my meaning and left quickly.

  23. vonskippy says:

    Don’t they make wallets with the huge redneck dog chain on them anymore?

    Seems like a dork meter toss up between the dog chain and the ginormously thick tin beeper glued inside your wallet.

    Personally, I carry a cash loaded pin controlled debt card in my shirt pocket, along with my medical insurance card, and my work id. I’m afraid most pickpockets would be very disappointed after they felt up my chest for such a dismal haul.

  24. Cricri says:

    Neat! Indeed, it is a bit thick. Maybe there exist thinner units, or you could trim out some more of the plastic casing, or only keep the PCB?

  25. Eirinn says:

    Pickpockets rarely work alone I’m afraid. If you catch one that already has their hand on your wallet he’s going to throw it to the accomplice if you chase him. An achievement would be to NOT let them get to your wallet in the first place.

  26. Oleksiy says:

    would work better with those magnetic rings that shut off the alarm,

  27. Fueg says:

    Easy way to defeat pickpockets is to sew/glue velcro to close your pocket. A pickpocket will not be able to put his hand down your pockets without you noticing because of the noise and effort needed to open the velcro.

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