This project is developed for the users to communicate voice from one place to other in wireless manner using laser. It mainly consists of two modules called Laser transmitter and Laser receiver.
Instead of RF signals, light from a laser torch is used as the carrier in this project. The laser torch can transmit light up to a distance of about 500 meters.
The transmitter circuit comprises condenser microphone transistor amplifier(BC 548), a modulator(BD139). The audio signal is mixed with the carrier beam and transmits through a laser torch.
A photo transistor is connected in the receiver circuit. The laser light is received by the photo transistor. The output is given to a two stage pre amplifier LM386 based audio power amplifier, and the output is given to a speaker.
To avoid 50 Hz hum noise in the speaker, keep the photo transistor away from AC light sources such as bulbs, tube lights etc