Using this circuit, audio musical notes can be generated and
heard up to a distance of 10 metres. 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 (LED1) flickers according to the musical
tones generated by UM66 IC, indicating modulation. IR LED2 and LED3 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.
SCHEMATIC :
2 comments
Click here for commentsCan you please reply me on how to convert this to a voice communication device ?
ReplyThis can be converted to voice communication device. In this circuit IC UM66 is used to generate input sound signal. To convert it into voice communication device apply your sound signal between pin no. 1 and 3 of IC UM66. Remove IC UM66 from circuit and the components present at the left hand side of IC UM66. Rest of the circuit will remain same.
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