FM transmitter with an effective range of 300 meters
This is the FM transmitter circuit is very simple and has a reasonable transmission distance. The signal transmitted by this FM transmitter can be received at a distance of 300 meters in open air. Power circuit requires a voltage of 3 Volts. Signal reception can be set to any FM receiver. The coil should be about 3 mm in diameter and have 5 turns of copper wire with a diameter of 0.61 mm. After mounting the coil on the Board extend the turns of the coil of 0.5 — 1 mm, so they are not touching.