Hidden Treasure Box Idea

Projects General Guidance
1

Hi,
I have a very rough idea for a kid's game like a treasure hunt. It would involve at least 2 boxes with Arduinos. One would contain the treasure and one would assist in finding the hidden treasure box. I imagine the assist box would have an lcd screen and give the user clues. The treasure box would possibly contain a speaker for sound when the treasurer hunter is close enough.

I have seen the GPS enabled treasure box that only open when in a certain location. My idea is for someone to put treasure in a box and then hide it around their house or outside. The treasure hunter then uses the other box to find the treasure.

My question is this: What is the best way to allow the the two boxes to "communicate"? Bluetooth? GPS? Xbee?
I imagine you would need at least 50 feet so that may rule out Bluetooth. I'm not sure how far that goes.

It would need to be able to calculate a distance as to give the treasure hunter clues.
What do you guys think? Is my idea possible?

Thanks.

2

How would they know they are close to each other? Think distance measuring would be important here.
Could use simple 315/434 MHz Tx/Rx modules, <$10/pair.
Not sure what you'd for signal strength, GPS location comparison, something along those lines.

3

Maybe put a hidden PIR in the treasure, it can start transmitting a different signal when something sets it off.

4

Yes, distance measuring would be important.
Do you have a link to the 315/434 MHz Tx/Rx modules CrossRoads?
I like the PIR idea too. I found one for under $7.00 PIR Sensors and PIR Modules

5

Sparkfun carries RF again, and this place has several to choose from
http://www.robotshop.com/433mhz-high-sensitivity-transmitter-receiver-pair-rxa30.html

6

Yup, Sparkfun has them as well. RF Link Transmitter - 315MHz - WRL-08945 - SparkFun Electronics
I also found a helpful tutorial for us Arduino folks. http://letsmakerobots.com/node/12336.
I've never used these modules before. I'll give it a try if I ever complete my current project.

Thanks Crossroads.