Micro FM Transmitter

This transmitter design is usually attributed to Japanese multimedia artist Tetsuo Kogawa. It takes audio input via 1 / 4 “phono jack, and built as shown, without additional antenna connection, will emit a radio signal about 30 feet.
This is a standard model Mr Kogawa is the simplest FM transmitter, which is slightly more complex than his most basic design in that it includes a trim capacitor to adjust the frequency of broadcasts. It can be powered by 9V battery and uses a hand-turned copper coil.

 

Source: make