Planet Arduino

Mike Buss used an Arduino Duemilanove, Parallax RFID reader, micro servo, and piezo electric speaker to make a personalized, lockable keepsake box for his girlfriend’s birthday:

The outside of the box is really simple: it just contains a button and an RGB LED. When she presses the button, the LED lights up green or red depending on if the box is locked. When she waves one of the three personalized RFID cards over the box, a little tune plays and the box unlocks.

As part of the project I also did some cool trick with a Pololu pushbutton power switch to make the battery last a lot longer. Since the Arduino is only powered for a few seconds when listening for RFID tags, the battery lasts a lot longer. When the box is finished locking or unlocking (or after a small time delay), it sends a signal to the power switch to turn off the power and conserve battery life. The box has been running on the same 9V battery I put in 4 years ago!

[Mike Buss] wanted to make his girlfriend something unique for her upcoming birthday — she had mentioned she wanted something to keep small mementos in, but [Mike] decided to step it up a notch on the awesomeness scale.

You see, a few years ago [Mike] read about the Reverse Geocache Puzzle by [Mikal Hart], which is an awesome box that gives you feedback as to how far away you are from the “secret” location that the box will open at — To raise the stakes however, if you ask for the distance more than 20 times it locks itself forever! Now, unfortunately, a memento box wouldn’t be very useful if you had to go to a secret place every time you wanted to open it… so [Mike] decided to secure it another way, using RFID!

It makes use of an Arduino, a Parallax RFID Reader, a micro servo, a button, an RGB LED, and a cleverly designed latch made of a metal eye hook and small copper rod. Since the box is battery powered, [Mike] has added an extremely clever fail safe mechanism. The 9V battery inside includes two extra contacts to the outside of the box via small screws. Completely inconspicuous, but if the battery is dead, simply hold a new 9V to the screws with the RFID card in place, and bam, the box opens!

We’re pretty sure she’s going to like it — check it out after the break!