This circuit, which has a power of a few tens of microwatts, is suggested by Maxim. The circuit has a range of about 20 meters with an antenna of approximately 1 meter. Both inputs can receive signals from an MP3 player or another device. The supply can be made with a voltage of 3 to 5 V. The coil L1 consists of 4 turns of wire 28 or close in a form of 1 cm without core. Basic tuning is done by tightening the turns. R2 controls the modulation and R1 adjusts the frequency, as the MAX2606 is a VCO.
