Infrared Hides Code Combination On Geocache Puzzle

[AJ] and [Brian] are making sure the geocache challenges they set up take some ingenuity to solve. They’ve just rolled out a two-part cache which uses a code hidden in infrared light.  (Editor’s note from the far future: link wend dead.  Have a look in the Wayback Machine.)

The first part of the cache is a box (the black one on the left) which contains a mysterious hand crank and a smaller box that has a combination lock on it. The second stage is the wooden box on the right. It’s got a hole in the side to receive the hand crank. This connects to the dynamo inside, letting you build up some electricity as it spins. Inside the case you’ll see two red lights blink as the crank is turned, but when you push the button on the outside of the box nothing will happen. That is, unless you’re looking through a camera which can pick up infrared light. The code (710 in this case) is displayed in an array of IR LEDs, and is used to open that combination lock. We wonder if there’s any clues about using a camera or if you have to figure this out on your own.

Don’t miss the video after the break for a full demo of the system.

11 thoughts on “Infrared Hides Code Combination On Geocache Puzzle

  1. Awesome! I love geocaching, where are you guys putting it? Somewhere in north-eastern NJ I hope?!?!

    Great puzzle, I love the really involved ones that make you think! Just going to find a box is fun, but figuring out clues to where the box is is even better.

    One thing, are you expecting them to return the hand crank to the 1st box? Might wanna make it close so they don’t flake on it.

    Great Job!

    1. Reminded me of this joke: A blonde goes to a auto parts store and asks for a Seven Ten cap. Everybody look at each other and ask, “What’s a seven ten cap?” She says…, “You know, it’s right on the engine. Mine got lost somehow and I need a new one.” “What kind of a car is it?” they ask.
      She says that it’s a Buick. “Okay, Lady, how big is it?” She makes a circle with her hands about 3 1/2 inches in diameter. “What does it do?” She says, “I don’t know, but it’s always been there.”
      One of the guy gives her a note pad and asks her if she can draw a picture of it. So she makes a circle about 3 1/2 inches in diameter and in the center she writes 710. The guys on the opposite side of the counter are looking at as she writes it…and they just fall down behind the counter laughing so hard. One guy says, “I think you want an OIL cap.”

  2. This is really cool if this is normally the LEVEL at which certain geocaching circles operate these days. Can you rate the level of difficulty with this one? How certain are you people won’t just think that the cool-ass crank and box are THE CACHE and just take it and replace it with a pack of gum?? I dunno.. I don’t do geocaching so I guess I wouldn’t know what the heck I’m talking about… Awexome idea though! BTW, my iPhone doesn’t seem sensitive to IR light like some of my previous phones… kind of stinks for me.. and maybe anyone with an iPhone finding this cache.

    1. You can probably use phosphorescent material to absorb the IR and re-emit at a visible wavelength. That won’t require a camera/phone at all. Just a sheet of glow-in-the-dark material.

    2. The clues on the cache detail page mention the crank and it’s importance. that particular crank was used because it is easily replaced if stolen. It also has marking on it indicating it is part of the puzzle. That is unfortunate for Iphones We will have to check that out, The LEDs are very bright so perhaps they will just show up dim on the Iphone. I like the phosphorous material idea above as well.

  3. I geocache a little, while an interesting puzzle without a way to see the infrared light it would take me about 10 minutes probably less to guess the combo on the lock wouldn’t be the first time I’ve brute forced the combo on those kind of locks the rotary ones on the other hand take much much longer.

  4. people go geocaching without an android in their hand? in 2012? the hint i would use would be a riddle about something that can’t be seen with the naked eye, along with some cryptic references to wavelengths and shit

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