If a crystal radio is the distilled essence of a radio, this transmitter is the matching distilled essence of transmitters.
The transmitter goes together in about 10 minutes, and is small enough to fit in the palm of your hand.
Depending on the antenna, the transmitter can send voice and music across the room, or across the street.
This is the transmitter off of http://scitoys.com .
Step 1: Stuff you need
A one megahertz crystal oscillator
This is a crystal clock oscillator such as those used in computers. There are many suppliers, such as
An audio transformer
This is a 1000 ohm to 8 ohm audio transformer, such as Radio Shack #273-1380.
A generic printed circuit board
I used Radio Shack's #276-159A, but any general purpose printed circuit board will do.
A phone plug
This should match the jack in your sound source. I use a 1/8 inch (Radio Shack #274-286A) plug to match standard earphone jacks of transistor radios and Radio Shack's Archer mini-amplifier speaker.
A 9 volt battery clip
I like the Radio Shack heavy duty type, part number 270-324.
A 9 volt battery
A set of alligator jumpers.
Radio Shack part number 278-1156, or you can find them anywhere electronics parts are sold.
Some insulated wire for an antenna.