Small Single Chip FM Transmitter Circuit Schematic Diagram
The following circuit schematic diagram is the one used for the monophonic FM Transmitter. It is pretty clear seen on the circuit’s schematic that the left and the right signal is mixed before modulate the radio frequency.
Maxim Semiconductor’s MAX2606 is the core of this circuit. It is an integrated circuit which is compact, high-performance intermediate frequency voltage controlled oscillators. The output from this circuit is -21 dBm radiation power, and work with 3 volts power supply, so two small batteries with 1.5 volts each should be enough. You just only need a potentiometer to tune in the frequency within commercial FM broadcast band 88-108 MHz. And that is the best part. The frequency tuning circuitry have been handled by the IC, so you don’t need to bother. External varactor even doesn’t need in this circuit. One of the application that can be used with this circuit, you can extend your mp3/CD player in your room to your portable set around the house. Much more simple than using wires. [Source : Maxim Integrated Products Application Notes]