I typically try to think outside of the box when it comes to gifts for my wife. Valentine's Days is one of those holidays that we have sort of been forced into buying things out of obligation, but rather than buy her more of what she already has, I decided to make something instead. A few nights before V-Day, I way laying in bed, and the idea for this project came to mind. The only problem is that I wouldn't have time or be alone to make in until the night before Valentine's Day...
So while I think this project has some potential to go somewhere, a lot of what I did could definitely be improved with more planning and preparation. The basic concept is a small, clear box (3 in3) that has painted designs on the inside of the box (to prevent them from getting scratched) with a small circuit that alters the brightness of a few red and while LEDs which illuminate the box from the inside. The trick to the box is that a small push button on the bottom of the box disconnects power to the circuit when it is resting on a table, but when the box is picked up, it begins to glow: hence, a "heart in the hands" box.
I have attached the programming files as well as a schematic for use in Eagle.
This is a short video showing the box in action. It also demonstrates a bit of what I mentioned earlier about improvement. The aesthetic quality of the box could be drastically improved with a better design painted on the box and more care in cutting the plexiglass casing. Note that the pulsing of the LEDs is only visible to the digital camera, but not to the naked eye. The color of the box does change over time as the different LEDs dim or get brighter.
Step 1: Materials and Such
When I started working on this project, I didn't entirely know where it was headed. This is a list of what I ended up using, but as usual, you might find something else works a bit better.
Sheet of Plexiglass - I used 9in3
Paint - Red, Black, White, etc
Drill with various drill bits
Dremel with Cutoff wheel(s)
Small Prototype board for circuit
Small push button
Various amounts of wire
8 pin Dip Socket
2 x 1uF capacitors
9V battery connector
1 x MOSFET with Vgs <= 9V
Various logic level MOSFETs
Various Red and White LEDs
Various sized current limiting resistors for LEDs