CIRCUITIDEAS108 • JANUARY 2007 •ELECTRONICS FOR YOUWWW.EFYMAG.COMUsing this circuit, audio musi-cal notes can be generatedand heard up to a distance ofFig. 1: Transmitter circuitFig. 2: IR audio receiver circuit±PRADEEP G.IR MUSIC TRANSMITTER ANDRECEIVERS.C. DWIVEDI10 metres.The circuit can be divided intotwo parts: IR music transmitter andreceiver. The IR music transmitterworks off a 9V battery, while theIR music re-ceiver works offregulated 9V to12V.Fig. 1 showsthe circuit ofthe IR musictransmitter. Ituses popularmelody genera-tor IC UM66(IC1) that cancontinuouslygenerate musi-cal tones. Theoutput of IC1 isfed to the IRdriver stage (built across the transis-tors T1 and T2) to get the maximumrange.Here the red LED (LED1) flickersaccording to the musical tones gener-ated by UM66 IC, indicating modula-tion. IR LED2 and LED3 are infrared
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