update 6/2014: audio version of the AM transmitter: https://reactivemusic.net/?p=12263
Forum thread which gives a sketch to generate Morse code at 1337khz, with no additional hardware.
Tried this sketch and it actually works – local version is:
- tune AM radio to around 1337 KHz
- Plug antenna (random length piece of wire) into digital pin 8
- open serial port set to 9600
- type in some text and press <return> (but not too much text at once)
Here is a link to a circuit using a crystal oscillator component and a serial port from windows computer to turn it on and off to make cw, also a suggestion (below) to expand it to use audio modulation…
To those wanting to send audio (as in music/voice): You will need an audio transformer. The transformer has 5 leads: 3 on left, 2 on right. The 3 lead side: connect the audio jacks ground on bottom, input on top leaving the middle lead free. The right side: batteries + supply on bottom lead, the top lead connects to the oscillators input pin. What you used as the ground should be the same. Just plug it into the computers “audio out” plug. To transmit music, play it with whatever music player you like. Plug it into a mp3 player/ipod/cd player and take it with you where ever you go. To send voice, plug mic into pc “audio/mic/line in” plug.
More details on voice modulation…