Christmas Present Shake Prank

We all know someone who shakes their presents to try to figure out what's inside. This project is the perfect thing to give someone who does this. It's a box that plays prerecorded sounds whenever an internal shake sensor is activated.

Materials:

• Cardboard Box
• RadioShack 9V recording module
• 9 volt battery
• 100µF capacitor
• 2 short pieces of magnet wire
• Hot glue and hot glue gun

This project is built around the RadioShack 9V Recording Module. It is a basic sound recorder with 20 seconds of memory. It has one button for the record function and one button to start and stop the playback function. For this project, we are making two modifications to the module. We are adding a wire shake sensor to activate the play function in place of the button. Additionally, we are adding a capacitor to temporarily disable the stop function so that the playback isn't interrupted.

Start by wrapping the positive lead of the capacitor around the positive terminal of the battery. Be careful not to make contact with the metal casing of the battery. This can create unwanted shorts. Then bend the negative lead of the capacitor into a "J" shape. This will form half of the shake sensor. To form the other half of the shake sensor, remove the any insulation from the ends of a piece of magnet wire and insert it into the negative terminal of the battery. Then attach the battery connector. This will hold the wires in place. Bend the magnet wire into a hook shape and position it as close as possible to the negative lead of the capacitor without making contact. When shaken, these two wires will make contact and activate the play function.

Then, attach this shake sensor to the play pin on the recording module. The play function is activated when the play pin on the module is connected to ground. This is normally accomplished by pressing the play button. In this case, we are using our shake sensor to make the connection. The shake sensor wire is already connected to the negative terminal of the battery. So now all we need to do is attach the other end of the shake sensor (the negative lead of the capacitor) to the play pin on the module. Take the second magnet wire, and remove any insulation from the ends. Insert the one end of the wire into either of the two pin holes indicated in the picture. You don't need to solder the connection. Just loop the wire through the pin hole and twist the wire against itself until it is tight. This should make a sufficient connection. Then twist the other end of the wire around the negative terminal of the capacitor.Shake the sensor to make sure that it activates the play function properly. If not, you probably need to adjust the position of the wires.

Once things are working, secure everything to the side of the box with hot glue. Shake the box a few times and adjust the wires so that they make contact when lightly shaken.

Record the sound effect that you think is most appropriate for your target. It can be a kitten mewing, glass breaking, or a train whistle. Be creative. Then all you have to do is put in the actual present. To prevent the present from bumping into the sensor and messing up the calibration, it helps if you secure it to the bottom of the box with hot glue. If you really want to pull off the illusion of something else being in the box you can also add some weight to match the sound that you picked. Wrap everything up and enjoy the spirit of giving.