An amplifier circuit to allow you to connect an 8-ohm speaker to your iPhone or other device's headphone output. Note: do NOT use a mono plug. Instead, use a stereo plug and leave the middle ring dangling.
2 transistor Spy Transmitter
Team Building Task-The Cup Challenge - take a rubber band and tie 6 strings to it (though I think 5 would work if you want smaller groups). Participants must use only the strings to move 6 cups into a pyramid formation. You can make this a competition between the groups or give them harder cup moving tasks.
wood work - Buscar con Google
Use a DIY Proximity Sensor to Automate Your Haunted House