Homemade Wireless Audio Reuters ----- FM Transmitter

First introduce the first one, it is still possible, the grade, it is equivalent to the Otuko, Xiali, Geei in the car, can be opened (indeed forwarding the audio signal), but sitting very uncomfortable (poor sound quality, single Sounds), safety is not available (oscillation frequency is unstable, very easy to interfere). Below is the circuit diagram of this Olympics audio repeater. Be Be Be Be The above figure, one triode 9018 constitutes an oscillator. The audio signal is input from the triode base, and the volatile diode characteristic of B-E is achieved. Although the circuit is simple, the sound quality is very poor, the stability of the oscillation circuit is very bad, the voltage changes, the human or metal can change the oscillation frequency near the antenna, resulting in unstable receiving ends. Moreover, the circuit can only transfer the mono audio, and the user can't listen to high quality stereo music. After two or three trials, I finally made a self-think of a relatively good repeater, at least equivalent to Camry, Accord what kind of grade. This time, a famous BA1404 stereo FM modulation chip is used. Since there is a pre-heavy circuit in the chip, the sound quality has been greatly improved. However, the biggest progress of this forwarder also comes from a single channel to stereo leap. This is equivalent to the upgrade of the car suspension system to the independent suspension, sitting comfortable. The following is a circuit diagram of BA1404:

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