The schematic shown here is a circuit of a 555 tracking transmitter. 555 is a famous versatile IC used in many electronic projects. In the below mentioned circuit this IC is used to generate a tone which will be transmitted through the FM transmitter circuit which is built around the 2N2222 transistor.
The circuit can be tuned between 103 to 108 MHz and will transmit at a distance of 100m. L1 is equal to 2 turns of #24 wire on 5mm form, and TR is equal to 1 to 30 pf trimmer capacitor. Antenna can be a 75cm wire, for full range keep the wire vertical, or you can also use small 6 or 12 inch wire as antenna but the range will become half or less. The circuit can be operated with 4.5 volt batteries of any type.