This 3 Volt Miniature fm transmitter can only transmit for short distances, but it is small. Having a small discrete FM transmitter can be useful. If you don’t want to consume too much power or have your transmitter too visible, then the smaller the better.
I prefer working on small projects like this one because when you create small electronic projects, then you can understand how the more complex ones work. Here is the parts list:
1 – 4.7k resistor
1 330 ohm resistor
1 0.001uf capacitor
1 10-40 pf variable cap
and then you will also need an electret mike, some magnetic wire for the antenna, and then a 3 volt battery. (source – http://www.uoguelph.ca/~antoon/circ/fmt2.htm). I would buy the magnetic wire at Radio Shack but order most of the capacitors from Digikey or Mouser. Variable capacitors are handy to have as well.