1-Watt FM Transmitter

1-Watt FM Transmitter

1 Watt FM Transmitter

This is a simple, portable transmitter operating in the 88-108 MHz FM band.

You may use it to run your own private neighborhood radio, just replacing the microphone capsule with a male audio jack connected to your pc or MP3 player. You may also use this as a spy transmitter, but be reasonable in that case! :D

It's rated for 1 Watt, so you can listen to it even from a few kilometers, with a good antenna and not too much obstacles in the way. 

FM-TX Schematic

Above you can see the schematic. I recommend to build it on a perf-board or better to etch its own board.
Please note that the L1 coil is made wrapping 4 windings of a 1mm copper wire on a 7mm long support, which will be removed before soldering the coil.
The C3 trimm-capacitor is used to select the transmission frequency, the R7 trimmer is used to modify the volume.
If you want, you may add a 70cm long wire as antenna near the first coil of L1 from the T2-collector side, or even better a ground-plane FM antenna with a shielded coaxial cable.
Be sure to add an heatsink to the 2N2219 transistor (T2), especially if you use an antenna.