The Doors Are Alive With the Sound of Music

Have you ever been sent one of those thick Hallmark cards, the ones that play music? When I started sorting through my things to move back home for the summer, I came across a few of these singing greetings. Not needing them anymore, I started taking them apart. Before long, I had turned my musical cards into musical doors, rigging various rooms in my house to sing when entered. If you find yourself wondering what to do with your old musical cards, you may want to check this out.

Singing cards contain speakers inside. These can be removed.

If you start to take apart the card, you will find that there is a speaker inside, hooked up to some kind of circuit. Chances are, both are coated in a sticky substance, allowing them to stick to the card. Carefully cut them out, allowing a part of the card to serve as their backing, lest you expose the sticky goo. The rest of the card can be, well, discarded. Recycle the paper, and let's get on with the project.

Carefully inspect the circuitry to figure out how the device is triggered. In all of the cards I had collected, there was a thin metal flap. A strip of paper separated the flap from the rest of the circuitry, but when the card was opened, the paper slid aside and allowed the metal to touch. This closed the circuit (I imagine) and started the music.

With a few household materials, you're ready to go.

All we need to do is simulate that operation. Only, instead of opening a card, we're going to be opening a door. Be sure that you are working on the side of the door that remains hidden while being opened. Affix the speaker to the top of the door, close to the hinge. Regular tape should do the trick. Next, cut out a strip of thick paper. The card you recently disassembled may do the trick; I cut up an old business card. Being careful not to bend the metal flap (lest you distort it, preventing it from snapping shut), slide your paper between the flap and the circuit, and attach the paper to the wall above (or to the side of) the door.

Test out your work. When the door opens, the paper should start to slide away from the musical device. Once the door is wide enough, the paper will be pulled away, allowing the metal to touch and triggering the music.

When the door opens, the speaker moves away from the paper, triggering the trap.

The trick is to get out of the room without ruining the setup. You may need to adjust the location of the paper until you find that you can open the door just wide enough to escape without setting off the trap.

There you have it: musical doors. Be sure to hang around so that you can see your target's face when s/he opens it!