IR Music Transmitter and Reciever

Transmitter circuit diagram:

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
photo-transistor L14F1 (T3). The IR music receiver uses popular op-amp
IC µA741 and audio-frequency amplifier IC LM386 along with
photo-transistor L14F1 and some discrete components (second diagram).

The
melody generated by IC UM66 is transmitted through IR LEDs, received
by phototransistor ceived 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.