For years, infrared LED has been merely a system for piping light around corners and into the inaccessible places to allow the hidden to be lighted. But now, infrared LED has evolved into a system of significantly greater importance and use. Throughout the world, it is now being used to transmit voice, television and data signals as light waves. Its advantages as compared with conventional coaxial cable or twisted wire pairs are manifold. As a result, millions of dollars are being spent to put these light wave communication systems into operation.
Objective of this project are to Design a circuit of an electronic infrared communication system, develop new ideas to implement this circuit purposely, to study the circuitry and different types of components & DTMF generator, DTMF decoder, op-amp and infrared-LED in the circuit.
The main part of Circuit is an amplifier. This sound signals (even at a distance of 2 meters from the mic) are picked up by the condenser microphone and converted into electrical variation, which are amplified by the op-amp. Operational amplifier IC- 741 is use in the inverting mode with a single supply using divider network of resistor the gain of IC can be set be varying the feed back through R5/6 resistance (can place a 1M variable) here the output of IC is further amplified buy the push-pull amplifier using transistor BC.548/558 pair, in this circuit are R2 is feed back resistance with R1/8 and C1/3 to connected IC-741. The IC’s pin 2 is connect VR1 (variable resistance) through connect to O/P of T1 (transistor) also use 6volt DC.