Reverse Geocache Puzzle


[Mikal] wanted to create an awesome electronic wedding gift for his friend who was moving to France. After experimenting with a few things, he settled on creating a puzzle box that would only open in a certain location. Since his friend introduced him to the Arduino, he fittingly used one in the design, along with a serial GPS module and a mini character LCD. The box itself is locked using a servo-controlled chopstick, which could theoretically be snapped if [Mikal] really screwed something up. To save battery life, he used a small Pololu module to provide power that uses only 0.01 microamps in standby, and can be shut off by the Arduino.

The box was designed to be mysterious yet self-explanatory. When the button on the front is pushed, the box comes to life for 3 minutes, displaying the distance away from secret location. Additionally, it warns how many tries are left: the button can only be pushed 50 times before it is sealed “forever”. In order to open the box, you have to be within 2km of the destination. Theoretically, you can narrow down the location to one of 2 points after 2 readings, but a less scientific approach would probably be a lot more fun.

This seems like an amazing gift, and the same concept could be repurposed into hundreds of other devices. For extra fun, he could have placed it at a geocache location.

32 thoughts on “Reverse Geocache Puzzle

  1. An awesome gift, to be sure. Certainly, the contents need to be either unbearably lame, or even more awesome.

    IMHO, the best thing to put inside the box would be, like Russian nesting dolls, a smaller version of the box set for yet another location. The recipient’s head just might explode, eh? Any guesses as to what words might flow from his mouth upon opening the box.

  2. Mikal – Brilliant! The hack, the puzzle, the gift. all brilliant.

    MikeW- One could use the same electronics for every successive box, just shedding the outer shell.

    I would like to see fewer external electronic. maybe a rotating wooden wheel of runes. or screen projected from the inside.

  3. That is awesome! and i love the idea of multi staging this. it would be so fun and even better as a gift. I’m thinking marriage proposal with the ring in the like 6th box =)

  4. you could add clock and only allow it to open at a certain time AND location…

    OR you could have multiple geocache locations, so maybe there is a “3 step” combination and in order to unlock the box you must go to each location in the right order and push the button at each of them…

    the box would tell you if you were right and maybe scroll some text with a clue to the next location.

    I really love this device, it’s a very cool concept.

  5. @Reid : it’s ok, the secret location is in jail anyway.

    And for someone moving to France, the best gift is a rope. I feel very sorry for the guy, he’ll regret it very quickly :(

  6. i like the combination lock idea… you could carve some sort of clues or whatever into the top that would signify where each location was, and instead of gps readout on the top, you could just have wooden dials that swing into place or something maybe when you get to each location

  7. Oh, and it would be even more interesting if there were some kind of secret transmitter inside. Like, every time you press it a cell phone dials out and logs to a secret twitter, and also something else that depends on location. For example, if you’re in France, it plays a really raunchy prank call to the foreign legion and tells them your current coordinates.

  8. Extrapolating further, we know someone who must have a wallet that contains technology like this, because it never f**king opens when he’s in the bar drinking beer paid for by others!

  9. Sounds nice, except for the “only be pushed 50 times before it is sealed “forever””
    First thing I would do, is to press that button like a mad.
    Deal with that, creator of a non fool proofed system!!

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