Make toys at home with common household materials, often in only a few minutes, that demonstrate fascinating scientific principles. See also the Science Blog, – Creator – Simon Field
This Website is a valuable resource for students to learn basics and get interested in electronics and computers – delabs
The motor is simply a battery, a magnet, and a small coil of wire you make yourself. There is a secret to making it (which I will of course share with you) which is at the same time clever and delightfully simple.
Other Projects – Fun with High Voltage, A 10 minute railgun, A 30 second motor.
The reason a crystal radio does not need any batteries is the amazing capabilities of the human ear. The ear is extremely sensitive to very faint sounds. The crystal radio uses only the energy of the radio waves sent by radio transmitters.
Others are Building a radio in 10 minutes, Build a portable crystal radio, A radio out of household items, A simple AM transmitter, The Three-Penny Radio.
In this project we will build a very simple radio transmitter that you attach to a serial port on your computer. The computer then runs a free program that converts words you type into radio signals that are decoded by another computer, using a cheap radio receiver, and a sound card.
More – A Free Space Laser Data Transmitter, Fun With Solderless Breadboards, A Simple 1 Watt Amplifier