Wireless transmission: FM wireless microphone circuit diagram with voltage regulator circuit

First, the principle is shown in the following figure, which consists of three parts: 1. The audio is mostly in. High frequency oscillation section; 3. Regulated portion. The signal is injected from the microphone MIC into the base of the triode VT1, and the audio signal is enlarged by the VT1 to the high-frequency oscillation circuit VT2 base, and then the antenna is emitted. The operating frequency of this circuit is between 85 and 104 MHz. Second, the selection of components MIC selects high sensitivity of the electret microphone, VT1 is 9013h, β≥125. Vt2 is 2N38666; β ≥ 90, L1, L2 uses a ∮ 0.71 mm enameled wire to use a porcelain capacitor by 4 and 10, C4, C5 and C6 on the ordinary ballpoint pen, and the error ± 5%. Three-terminal regulator with LM7806 power supply, with a 9V battery, board can be self-made. Third, assembly and debugging circuit assembly is simple, as long as the components are not damaged, it can be successful. After the circuit welding, then the antenna is welded, the antenna uses 0.5 meters radio antenna, put the microphone at the sound source, then leave the microphone 5 ~ 6 meters long, open the FM radio, adjust the set button, if you receive The turbid harmonic can be used to adjust the spacing of the oscillation coil L1, and the frequency of the L1 is raised, and the effect is reduced. At this time, it is not a harmonic sound. If you want to increase the emission power, change the length of the emission antenna, or replace the VT2 emission tube to a 34D50 triode, and R4 electrical resistance is converted to 4.7 kΩ, and the emission distance can be increased by about 100 meters. (Transfer from Wiku Electronic Development Network)

Leave a message 

Message List