GPS Puzzle Box

The following photos are the reason why there hadn’t been much progress of late on the other projects. I initially came across a website by a guy called Mikal Hart who made a “Reverse Geocache” for a friend for a wedding present. The idea is based around a locked box that will only open on one place on earth. James decided that he liked the idea and wanted one…

BOOM! Finished project, Solid Aluminum case, all screws soldered or glued, MK1 of the impenetrable GPS puzzle box.

Press the button on the front and the box comes to life. There is a limited number of times you can press the button however, once used up the box will refuse to open at all. If you still have tries left however and if the box can get a GPS fix then it will give you a distance to your destination and then power off. If you are within a certain distance of your destination then it will open.

A couple of coolish parts to the circuit;

High Sensitivity GPS receiver, 15 sec warm start time in tests, RTC with battery backup, built in Data logger, 5v safe inputs and cool flashing red LED.

On the Left, Pololu 5v boost regulator. Will take input voltages from 0.8V up to 5v and provide a 5v output with a current varying depending on the input voltage. At 3v in it will give you 200mA.

On the Right, Pololu pushbutton power switch. Toggles output on and off at the press of a momentary pushbutton switch. Draws under 0.01 μA in standby mode, also provides a OFF input that when brought high will cause the switch to turn off. This means that the Arduino board is able to effectively switch off (but not on) its own power supply. Because of the low standby current, the box running on 3 x AA batteries should last a couple of years before the batteries need changing.

I do have to say a BIG Thank You to Peter for his help, time and machining skills in designing and making the locking mechanism for the box, without it this project would have been much more hillbilly and nowhere near as precise.

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