The laser beam is very well modulated by sound vibrations. It is enough to connect the module from the laser pointer to the output of the low-frequency amplifier and you will have a ready-made audio signal transmitter in the light range. Any solar battery is capable of receiving and converting light into sound. Even without an amplifier, it is enough to connect a high-impedance headphone to its output and you will hear the sound transmitted through the light.
Will need
Scheme
The presented circuit can be divided into two parts: on the left is the receiver, on the right is the transmitter. The sound from the smartphone is sent to a low purity amplifier. Next it goes to the laser diode. The oscillations modulate the laser beam, which is directed towards the solar cell. From it the signal goes to another amplifier. It is amplified and sent to the dynamic heads.
Assembling a circuit for transmitting sound using a laser beam
We solder the laser module to the output of one of the amplifier channels.
We take a wire to connect to the smartphone.
Solder to the amplifier input.
We connect power to the amplifier from a set of batteries.
The sound transmitter is ready. Let's move on to making the receiver. We connect the input channel with a jumper and solder the output from the solar battery to them.
Solder the wires to the speakers.
Solder the wires from the speakers to the amplifier.
Test in action
Turn on playback on your smartphone. We direct the laser point at the solar battery.
As a result, clear, distinct sound is heard in the dynamic drivers. See the video below for a closer look.
At night, this installation can transmit sound over a distance of up to a kilometer. Naturally, everything is limited by the power of the laser module.
