Frustromantic Box, A Reverse Geocache

One of the best feelings in the world is when one of our posts inspires a fellow hacker to plan, create, and execute his or her own project.

[Russ] let us know about his Frustromantic Box which he gained inspiration from the original Reverse Geochache we posted about. For those out of the loop, the box is locked and will only open in a certain location. The current distance to the  location is displayed on the screen when a button is pressed, and usually there is a limited number of button presses (3 presses for those that know geometry, 50 for everyone else). As soon as the box is at location, it will open.

The Frustromantic Box uses an Arduino, classic HD44780 display, a servo, and the pièce de résistance EM406 GPS. All built in time to frustrate his wife for Christmas.

45 thoughts on “Frustromantic Box, A Reverse Geocache

  1. While this is an awesome idea, I can’t help but think the subset of people clever enough to work out how to do this, but not too nerdy to make it boring by triangulating on a map is rather small.

  2. geocaching is retarded…. hurf durf look at me guys I have a gps i can walk towards other arbitrary spots so I can open a stupid box to receive a worthless prize and replace it with something else equally as worthless….. I can never see why this “hobby” got to be so popular

  3. Geocaching is awesome. For one, it’s an outdoor ‘sport’ and while it may not be everyone’s cup of tea, it is a nice way of interfacing technology and the outdoors. Basically, you get to be active by going outside and hiking/walking/climbing and maybe even social if you invite someone to go along.

    Which brings me to the second point. I just read about the previous box again last night, with hopes of building it. This post is just another impetus to get me going on it. I’m glad to see that other people find this project as interesting as I have.

    Every single post of yours is filled with childish, annoying discourse. I don’t see why you even bother coming to hackaday if you are just going to complain and comment how pointless everything is.

  4. @kirov

    It caught on because it made someone happy to do it. You know, like constantly complaining about other peoples hobbies makes you happy.

    I think this would be great for a few friends of mine, who have given me great gag gifts in the past. Now, to set it for a crowded place with an automated fart sound machine and a can of instant fart on tap when the lid opens…..

  5. @kirov

    All what you do in Hack a day is attack other people ideas. “oh look at me… oh look at me” thats all you know. Guess what? nobody wants to look at you.
    If you think everything is bad, c’mon, post your own hacks and show us what is a good creation.

  6. You could get it pretty reliably in two presses.

    You just go to the beach and press it, then move further up the coast and press it again. You now have two possible locations where it could be, and one of them is likely out in the middle of the ocean. Unless the location is chosen randomly or the person who set it is particularly cruel, it’s probably not out at sea.

    Or if it randomly choses within a certain distance of where you currently are – pick two points fairly far away and click it at each one. Now you again have two possible points, one of them being fairly close to where it was set, one being very far away. Unless it picks the coordinate when you click the first time, then you still have two points to check…

  7. Couldn’t you do this in 2 presses?

    Draw a circle around your position, then move and do it again, there will only be 2 locations where the circles intersect, it is possible to check both locations.

    Or get close to one location and far from the other and use the third press.

    I like it, very cool.

  8. I’d think you have to press the button when you think you are in the right location. Keeping the GPS on the whole time would suck the batteries dry in an instant. So 4 presses?

  9. @nubie

    Your 2 circle method is flawed. You don’t know how big or small a circle to draw on your map. The two intersections where your circles meet are only based on how big or small you make the circles and will vary wildly based on your cirle size. It won’t work. Triangulation is the way.

  10. I can find it in two presses.

    I have a 50% chance to be correct on the first go. Often, you can narrow out the wrong hit (ie, it’s in the middle of a highway, or water)

    (two presses. draw a circle out of the displayed range centered on your location when you press. Circle intersections are the possible locations.

    The third press would only be necessary if you couldn’t reason one of them out, or just try both.

  11. @jimmie

    you obviously fail to grasp what this box does. It tells you a DISTANCE from the boxes location to the unlock location. You know where you are when you press the button – and a radius (distance) for the circles.

    Everyone claiming they can use triangulation on this is wrong. Triangulation lets you find the DISTANCE to a distant object by walking between two points and using that distance as a side of a triangle. From each end of this ‘side’ you measure the angle relative to this side that would aim a leg of the triangle towards the distant object. With one side’s known length – and two adjecent interior angles, one can find the lengths of the remaining two sides of the triangle and thus TRIANGULATE it’s position and distance relative to either end of your known ‘side’.

    Distance is what you ALREADY have from the gps box, and you can’t SEE this point in order to ‘triangulate’ it’s exact location / distance.

    Assuming you must press the button in the correct spot, and either potential answer from the overlapping circle method is on land, wouldn’t one need 3 _or_ 4 presses to certainly find the goal?

  12. Not bad at all… the one I made I didn’t limit to x many presses but I did make it require you to go to 5 different locations before it would unlock (and I build my self a safety of it opening in a particular location every time bypassing the software seals). I sent the link to Mikal already though… i should take better pictures of its guts though and resend.

    Managed to hide all the wires inside the lid too.

  13. Fun idea like the first one. But why on earth would one put bare EM406A GPS module showing through the lid and otherwise trying to make the box look good.

    IMHO the ugly GPS module ruins the looks completely so it looks just like a “hack” and nothing else.

  14. @smilr… Correct. This is not triangulation, which uses direction to a target. It is 2D trilateration, similar to the kind the GPS is using, except minus a dimension… Or, maybe if the person who set the location is particularly evil, it could be somewhere off the ground, such as on a particular floor of a tall building or in mid air. This would require 3D trilateration (spheres instead of circles), which would be annoying to figure out how to map. That is not too practical, though, as altitude on GPSs is not incredibly accurate.

  15. Also, as for the button press limits, I would imagine that the device would show the distance for the three allotted button presses. Then, for each additional button press, the device would check to see if it is in the right place, but would not show distance.

  16. The original description explains pretty precisely how the box works. If anybody missed it, click the article link titled “Reverse Geocache,” and the original author describes it fairly clearly. In short:

    Whenever the button is pressed, the box does the following.
    1: check counter. If counter is over limit, inform the user, and then shut down. Else, proceed to 2.
    2: check location. If location is within [error] of [goal location](2km of the center of a particular island in the original case), unlock. Else, proceed to 3.
    3: get distance to [goal location]. Print a message on the screen to the effect of “You are [distance] away from where you need to be for this box to open.”
    4: Shut down.

    So the absolute minimum number of presses is 1, if you happen to be close enough to your goal on the first try. Not likely.

    The first box took the recipients to the island where they fell in love. I suspect this box also directs the designer’s wife to a similarly significant location, such as where they first met, or where he proposed to her.

  17. Putting a ring inside here would be the sweetest proposal ever.

    Also, it would be fun to give this to a non-techy person, because they would eventually figure it out, and they would enjoy even the process of figuring it out.

  18. @smilr


    you obviously fail to grasp what this box does. It tells you a DISTANCE from the boxes location to the unlock location. You know where you are when you press the button – and a radius (distance) for the circles. ”

    Yup, I failed to grasp that… orrr I just read it wrong at 4AM. I read it as direction, then saw the three presses for geometry and that’s how it stuck in my head.

    woops. /shrug

    It’s Jimmy btw, not Jimmie, thanks.

  19. Any sailor can tell you how this works- With each press of the button you get a circle of position (COP). Two COP’s intersect at 2 points (unless you are _astonishingly_ lucky and the edges just touch each other). Three COP’s can only intersect at 1 point in a two dimensional space.

    Sailors use this with RADAR ranges and sometimes by bobbing lights.

  20. How about fake GPS signal from signal generators? It is also possible to prevent this type of cheating by time lock and/or accelerometers… The GPS sensor should not accept too strong signals (fake). Then you could go to underground to circumvent this. So the GPS should somehow (GSM,…) know are you on the ground or not.

  21. I have built a puzzle box based on Russ’s design with a lot of help from him.
    It has a single servo opening the lid. I built it as a puzzle box for a geocache that I hope to have listed soon. I modified the sketch he provided to use a single servo and use a micro switch for the “backdoor”. I have has a couple of geocachers try it out and it worked well. I hope to have a blog about the build online soon.

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