Infrared Communication System is a device for I/R audio communication through transmitter and receiver up to a distance 10 meters. Infrared remote control devices are abundant in today's gadget-filled world. From the television and video recorder, through the Hi-Fi and on to the garage door that thankfully opens remotely on a rainy day, a remote controller of one form or another is never far from reach. Why use infrared light to send the control signals? Two reasons in particular stand out. The first is that the diodes used to emit infrared light are quite inexpensive and readily available. The second is the fact that infrared light is at a wavelength outside of the spectrum of visible light – so we can point and shoot our controllers and not get blinded in the process!

So how exactly does infrared remote control work? At the most basic level, the remote controller contains a transmitter circuit, part of which will be an Infrared Light Emitting Diode (IRLED). When a key is pressed on the controller, the command is sent as an IR signal to the device which you are aiming the controller at. The device being controlled will have a receiver circuit, part of which will be a photodiode with which to detect the IR signal and convert it into an electric current.
That's a very simplistic view of IR RC communications. However, when you factor in background infrared "noise" emitted by other heat-generating objects and multiple IR remote-controlled devices located in close proximity to each other, things quickly become more complicated. With simple infrared light, there is now potential for the command not getting to the receiver at all, let alone the receiver in the intended device. Using this circuit, audio musical notes can be generated and heard up to a distance of 10 meters. The circuit can be divided into two parts: IR music transmitter and receiver. The IR music transmitter works off a 9V battery, while the IR music receiver works off regulated 9V to 12V. Fig. 1 shows the circuit of the IR music transmitter. It uses popular melody generator IC UM66 (IC1) that can continuously generate musical tones. The output of IC1 is fed to the IR driver stage (built across the transistors T1 and T2) to get the maximum range. Here the red LED (D3) flickers according to the musical tones generated by UM66 IC, indicating modulation. IR LED D1 and LED D2 are infrared transmitting LEDs. For maximum sound transmission these should be oriented towards IR phototransistor L14F1 (T3).The IR music receiver uses popular op-amp IC µA741 and audio-frequency amplifier IC LM386 along with phototransistor L14F1 and some discrete components (Fig. 2). The melody generated by IC UM66 is transmitted through IR LEDs, received by phototransistor T3 and fed to pin 2 of IC µA741 (IC2). Its gain can be varied using potmeter VR1. The output of IC µA741 is fed to IC LM386 (IC3) via capacitor C5 and potmeter VR2. The melody produced is heard through the receiver’s loudspeaker. Potmeter VR2 is used to control the volume of loudspeaker LS1 (8-ohm, 1W). Switching off the power supply stops melody generation.

Infrared Communication System is a device for I/R audio communication through transmitter and receiver up to a distance 10 meters. Infrared remote control devices are abundant in today's gadget-filled world. From the television and video recorder, through the Hi-Fi and on to the garage door that thankfully opens remotely on a rainy day, a remote controller of one form or another is never far from reach. Why use infrared light to send the control signals? Two reasons in particular stand out. The first is that the diodes used to emit infrared light are quite inexpensive and readily available. The second is the fact that infrared light is at a wavelength outside of the spectrum of visible light – so we can point and shoot our controllers and not get blinded in the process!

So how exactly does infrared remote control work? At the most basic level, the remote controller contains a transmitter circuit, part of which will be an Infrared Light Emitting Diode (IRLED). When a key is pressed on the controller, the command is sent as an IR signal to the device which you are aiming the controller at. The device being controlled will have a receiver circuit, part of which will be a photodiode with which to detect the IR signal and convert it into an electric current.
That's a very simplistic view of IR RC communications. However, when you factor in background infrared "noise" emitted by other heat-generating objects and multiple IR remote-controlled devices located in close proximity to each other, things quickly become more complicated. With simple infrared light, there is now potential for the command not getting to the receiver at all, let alone the receiver in the intended device. Using this circuit, audio musical notes can be generated and heard up to a distance of 10 meters. The circuit can be divided into two parts: IR music transmitter and receiver. The IR music transmitter works off a 9V battery, while the IR music receiver works off regulated 9V to 12V. Fig. 1 shows the circuit of the IR music transmitter. It uses popular melody generator IC UM66 (IC1) that can continuously generate musical tones. The output of IC1 is fed to the IR driver stage (built across the transistors T1 and T2) to get the maximum range. Here the red LED (D3) flickers according to the musical tones generated by UM66 IC, indicating modulation. IR LED D1 and LED D2 are infrared transmitting LEDs. For maximum sound transmission these should be oriented towards IR phototransistor L14F1 (T3).The IR music receiver uses popular op-amp IC µA741 and audio-frequency amplifier IC LM386 along with phototransistor L14F1 and some discrete components (Fig. 2). The melody generated by IC UM66 is transmitted through IR LEDs, received by phototransistor T3 and fed to pin 2 of IC µA741 (IC2). Its gain can be varied using potmeter VR1. The output of IC µA741 is fed to IC LM386 (IC3) via capacitor C5 and potmeter VR2. The melody produced is heard through the receiver’s loudspeaker. Potmeter VR2 is used to control the volume of loudspeaker LS1 (8-ohm, 1W). Switching off the power supply stops melody generation.