Using this low cost Project one can reproduce
AUDIO from TV without disturbing anyone. It does
not use any wire between TV and HEADPHONE. In
place of pair of wires it uses invisible
Infrared light to transmit audio signals from TV
to Headphone.
Without using any lens a range of
up to 6 meters is possible. Range can be
extended by using Lenses and Reflectors with IR
sensors comprising transmitters and receivers.
IR transmitter uses two-stage transistor
amplifier to drive two IR leds connected in
series. An audio output transformer is used (in
reverse) to couple Audio output from TV to the
IR transmitter. Transistors (BC547) & (BD140)
amplify the audio signals received from TV
through audio transformer low impedance output
windings (lower gauge or thicker wire) are used
for connection to TV side while high impedance
are connected to the IR transmitter. This IR
transmitter can be powered by 9v mains Adaptor
or 9v Battery. Led in transmitter circuit
functions as power-on indicator. IR receiver
uses 3-stage transistors amplifier. The first
two transistors (BC549c)from audio signal
amplifier. While the third transistor(BD139)is
used to drive a headphone. Adjust potmetre for
max clarity. Direct photo transistor towards the
IR Leds of transmitter for max range. A 9v
Battery can be used to receiver circuit for
portable operation
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