Lock Box Power!
The Keyless Lock Box is designed to use external power for unlocking, but it can sit in a locked state for indefinite periods without any power. To power the lock and open it, insert the plug into the hole in the back, enter the combination, then lift the lid.
The box will automatically relock after 7 seconds. If the lid is still open, you can relock the box by manually pushing the servo arm toward the front of the box, pressing the Arduino’s reset button, and closing the lid. When the sketch restarts, it automatically moves the servo to its lock position. You may then remove the power plug.
If you forget the combination or can’t get it to work, here’s a “secret” override procedure that will briefly unlock the box:
Unplug power to the Arduino. Press and hold down the OFN sensor while you plug the Arduino back in. Quickly open the lid when you hear the servo move to its unlock position. You’ll have only 1.5 seconds before the servo relocks the box.
You can remove or comment out the override code in LockBox.ino if you don’t want this behavior.
Keep the box looking good by applying paint or finish to the bare wood, starting with a base coat. For a cleaner look, remove the clasp in front of the cigar box, and fill in the holes with wood putty. Sand for a smooth finish. Or replace the clasp with something fancier.
This project first appeared in MAKE Volume 32, page 110.