1.5V miniature wireless FM microphone circuit

The circuit shown in this paper uses 12 components to form a miniature wireless FM microphone with stable operating frequency, and its transmitting distance is about 30 meters and more than 100 meters at 6V power supply.The circuit is shown as Figure, BG1, C1 and C3 form a high - frequency oscillation circuit. The transmitting distance is related to the current of the launch tube, and the upward bias resistor R2 can change BG1 output current.If you select BG1, tube's fT must be greater than 300MHz, but if the fT is too high, it will affect modulation. Inductance L uses two coils to make wound, but the wound must be the same, L1 uses 0.5mm enameled wire with 4 turns in a diameter of around 5mm-diameter skeleton, L2 has 3 turns. The antenna can be made by a soft wire with 0.6 meters length.