Photoelectric-acoustic conversion circuit a

The working principle of the circuit is as follows: This circuit connects two simple conversion circuits of electricity to light and light to electricity and sound with optical fibers for experimental demonstration
. Figure a shows the electrical ■乜 conversion circuit. The audio signal output from the headphone jack of the radio, portable music player and other audio sources is input through the socket xs, and is amplified by the VT to drive the LED to emit a light signal
modulated by the audio electrical signal to complete the electrical-to-optical conversion. The function of Ri in the circuit is to match the input impedance of the circuit with the output impedance of audio sources such as radios and Walkmans.     Figure b shows, }electric sound conversion circuit . The light signal emitted by the LED is transmitted through the optical fiber and then received by the photosensitive diode VI. The VLS converts the received light signal into a weak electrical signal. This electrical signal is amplified by a preamplifier composed of transistor VT and other components, and then sent to the LM386 integrated circuit for power amplification, which drives the speaker BL to restore the sound and realize the conversion of light, electricity and sound. RP in the circuit is the volume adjustment potentiometer.