Abstract: This paper presents design of the circuit, using this circuit we can communicate with our neighbors wirelessly. Instead of RF signals, light from a laser torch is used as the carrier in the circuit. The laser torch can transmit light up to a distance of about 500 meters when IR sensor is accurately oriented towards the laser beam from the torch. If there is any obstacle in the path of the laser beam, no sound will be there from the receiver. The transmitter circuit consists of a condenser microphone transistor amplifier BC548 followed by an op-amp stage built around µA741. The value of gain of op-amp can be varied with the help of 1-mega-ohm pot meter VR1.The AF output from IC1 is coupled to the base of transistor BD139 (T2), which modulates the laser beam. The power supply is firstly stepped down through a step down transformer which is further rectified through a rectifier and 9V power supply is given to the transmitter circuit. However, the 3-volt laser torch is directly connected to the circuit with the emitter of BD139. The receiver circuit uses an IR sensor that is followed by a two-stage transistor pre-amplifier and LM386 audio Power amplifier. The receiver does not require any complicated alignment. Just keep the IR sensor oriented towards transmitter’s laser point and adjust the volume for a clear sound. While using circuit keep the IR sensor away from AC light sources such as bulbs. The reflected sunlight, however, does not cause any problem. But the sensor should not directly face the sun.
Keywords: Laser, LST, RF, LM386, Wireless.
Title: Laser Communication System
Author: Ankit Vijayvargia, Ajay Bharadwaj, Kshitij Jangir, Khushboo Kumari, Isha Arora, Neha Garg
International Journal of Electrical and Electronics Research
ISSN 2348-6988 (online)
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