Captain Crunch Geocache

Construction Guide

[ by LinuxOnTheBrain ]

Introduction

    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 (variable frequency setting), 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!
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    Introduction
    Acknowledgments
    Preface
    Legal Notice
    Materials List
        Electronics
        All Other Materials
    The Electronics Pack
        Hacking The Voice Module
        Circuit Assembly
    The Casing
    The Center
    The Tall Side Back
    The Short Side Back
    The Short Side Front
    The Gearbox
    The Door
    The Short Side Lid
    The Tall Side Lid
    Assembly And Testing
    Painting
    Final Assembly
    Recommended Changes

Preface

Please read this document completely before beginning the project. The builder needs to be aware of a number of things to avoid any problems and to take advantage of the recommended changes. It should be noted first that because most of the materials used were recycled the builder is encouraged to use what's available...be creative. Also important is that many of the measurements used in the design documents were taken indirectly (inferred) because they were taken after assembly so please double-check measurements and fittings during construction.
Distributed with the construction guide pack are the original Xfig design documents. Xfig is a wonderful open-source (free) program similar to CAD and is available primarily for Linux. There is also a ported version for Windows. Xfig is an excellent tool for anybody interested in drafting project designs. If errors are found please let me know so the construction pack can be corrected.
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Legal Notice

(I don't know if I really need this but just in case here's one that works...)
This construction guide and its contents are distributed under the GPL license:
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Captain Crunch Electronic Geocache

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
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Materials List

Below are the materials that were used to construct this geocache. Replace with materials with you have where possible and/or appropriate.
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Electronics Materials