This Transmitter can be powered by a battery 9V (not more than 12V). You can connect your music source where the microphone is or use a simple condenser microphone. The range of signal can reach 400 meters in open air. The wide range of frequency is up to you. Tune it at FM band (88-108) or TV band 40-80Mhz. Play with the Coil and the variable capacitor to tune it to any frequency you want as long as you got the receiver.
The circuit is as simple as it gets. First stage is the pre-amplifier with BC547 transistor and second comes the transmitter which use the 2N2222 transistor. For antenna use a half meter wire, but for best results the length has to be relative to wave length. A telescopic antenna can be used also.
For example at 90Mhz the length has to be around 80cm, at 95Mhz should be 75cm long, or at 100Mhz should be 70cm and so on.
The coil L is a 0.8mm wide wire, formed on a 4mm coil diameter. The number of turns and the air distance between the turns depends on the frequency you want to choose.