Captain Crunch Geocache

[   by LinuxOnTheBrain   ]

!!  Do Not Read Below If You Intend To Hunt This Geocache  !!
!!  Located In The Cedar Falls, Iowa Area  !!

    This is an electronic geocache with an audio triggered lock inspired by John Draper, a.k.a. 'Captain Crunch'. In the early 1970's John and his phone phreaker friends discovered that a toy whistle being included in boxes of Cap'n Crunch cereal played a tone which could be used to control the (now retired) in-band signaling long distance telephone network. The phone companies used this tone to control long distance line connections, when played it would disconnect one end of the call leaving the remaining caller in Operator Mode. John and his friends quickly realized that Operator Mode = Free Phone Calls and the rest is telecom history.
    To open this geocache the user has to figure out the frequency of the toy whistle and add 1000Hz, then record a sample of that tone and bring it to the cache. At the cache the user must find the 'key' located on the cache, insert the key into the keyhole to power it up then play the pre-recorded tone to open the lock.
    Most of the materials used to build this unit were recycled from something else or I fashioned them myself from scraps. (To be earth friendly of course). I hope this inspires others to build electronic geocaches since disposable electronics are everywhere and can be easily reused. Feedback is appreciated. Thanks and enjoy!

Construction Guide

View Online

Download Construction Pack

Video (320x240 10.5M) 05:55

Windows Streaming

Standalone Players


Circuit Schematic PDF

Click on any image for a larger view

Last updated 7/16/08