http://sci-toys.com/scitoys/scitoys/radio/ten_minute_radio.html
For our 10 minute radio, we will need these parts:
- A ferrite loop antenna coil
In our other crystal radios we wound the coil by hand. In this project we use a much smaller coil with a ferrite rod inside, from our catalog. The ferrite rod allows the coil to be smaller, and it can be moved in and out of the coil for coarse tuning.
- A variable capacitor (30 to 160 picofarads)
We carry this in our catalog. You can also find them in old broken or discarded radios.
- A Germanium diode (1N34A)
We carry this in our catalog.
- A piezoelectric earphone
Also in our catalog.
- Two alligator jumper wires
We use alligator jumper wires here for convenience. They are used to connect the ground and antenna wires to a good ground and a long wire antenna. We carry these in our catalog.
- About 50 to 100 feet of stranded insulated wire for an antenna.
This is actually optional, since you can use a TV antenna or FM radio antenna by connecting our radio to one of the lead-in wires. But it's fun to throw your own wire up over a tree or on top of a house, and it makes the radio a little more portable.
- A block of wood or something similar for a base
