Play hide-and-go-seek with infrared LEDs

Although we’re sure they exist, we wouldn’t want to meet anybody that can’t look back fondly on the halcyon days of youth that included playing hide-and-go-seek. Some kids never grow up and continue the tradition with geocaching or orienteering, but that sense of limitless discovery wanes over time. [Kurt] came up with a small scavenger hunt beacon that brings back the unending wonder that accompanies the unknown.

The beacon is just a simple ATtiny13 that flashes a message with an invisible IR LED. To receive the messages, [Kurt] made a scavenger decoder shield for an Arduino. The decoder includes a phototransistor and a 20×4 LCD display. All [Kurt] needs to do is hold the decoder up to the beacon for the text in the firmware of the ATtiny to be displayed. The beacon is only one inch square and powered by a watch battery, so it can be hidden anywhere.

[Kurt] suggests that the text of one beacon should provide the clue to the next. We’re thinking this is just a great excuse for a walk in the park. You can check out [Kurt]‘s IR decoder getting data from a beacon after the break.


  1. HackJack says:

    Since the cell phone camera can pick up infrared, IMHO, it would be much more practical and economical to come up with an Android/iPhone App as a reader.

    • Anthony says:


      Thats a good idea, but I doubt it would work the way it is, I’m not sure how fast he is flashing because his site is down but I doubt that most cell phone cameras are going to be able to see the actual “flashes” just a single light … but you could slow down the flashing enough to make this work

    • Jan says:


      Bluetooth beacons would be better then…

  2. Alex Rossie says:

    Played hide and seek in switzerland in a log cabin with no power in sight. Friggin’ epic

  3. NewCommentor1283,ihatetorx says:

    it could be used like a member identification for REAL non-lethal SHOOTING games!

    like in videogames where u can read if the player in front of u is enemy or team and thier name, this one needs an actual HUD lcd that is part see through and glued to goggles :D oh and targeting and and and …. XD

  4. Dave says:

    This is cool. Along with a clue of where to look next, it could check an electronic checkbox so you’re forced to find them in order.

  5. barry99705 says:

    Aww! I thought they were going to be some kind of cool beacons you use with night vision goggles…

  6. marcus says:

    what is the distance between the emitter and the decoder?

    looks very interesting!

    good job.

  7. kmmankad says:

    Can be made even smaller..go for smd!

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  9. Tobias says:

    Many years ago I have build this analog IR scavenger hunt device.

    The IR transmitter sends short tone modulated IR pulses, the receiver turns them into audible tones. The closer you come to the transmitter the louder is the sound that can be heard in the headphones connected to the receiver.

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