Here's a small FM transmitter ciruit for your desktop or laptop to enjoy the movie and music from a distance. This FM transmitter, which is powered by USB, recovers output on your computer or your MP3 player to the relay on the tape FM (frequency 108 MHz). For Assemblying this FM transmitter kit, an electronics hobbyist will have built in about 30 minutes.
USE DIPOLE ANTENNA FOR MAXIMUM RANGE (COULD BE UP TO 10 KM IN GOOD WEATHER). TUNE BETWEEN 88-108 MHz WITH C5. BB-204 COULD BE REPLACED WITH CONVENTIONAL LED (BIG) WITH REVERSE BIAS (NO LIGHT GIVEN IN CORRECT POLARITY). 9V POWER FOR 2KM WITH GOOD SOUND QUALITY AND GRADUALLY UP TO 18V FOR 10 KM RANGE WITH POOR QUALITY OF SOUND. BEST OF LUCK.
This one is a high power long range (use yagi antenna) FM Transmitter that provides very good frequency stability in about 1km range and very good microphone sensitivity. It can be used inside guitars, as a part of remote control systems or in other similar applications.
The features said above are achieved by including an RF amplifier stage with 10dB gain and AF preamplifier stage to boost the modulation.