Infrared cordless Headphone Amplifier

Using this low cost project, one can reproduce audio from a TV without disturbing anyone. It does not use any wire between the TV and headphones. Instead of a pair of wires, it uses invisible infrared light to transmit audio signals from the TV to the headphones. Without using any lens, a range of up to 6 meters is possible. The range can be extended by using lenses and reflectors with IR sensors comprising transmitters and receivers. The IR transmitter uses a 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 the TV to the IR transmitter. More: Transistors (BC547) and (BD140) amplify the audio signals received from the TV through an audio transformer. Low impedance output windings (lower gauge or thicker wire) are used for connection to the TV side, while high impedance is connected to the IR transmitter. This IR transmitter can be powered by a 9V mains adapter or a 9V battery. An LED in the transmitter circuit functions as a power-on indicator. The IR receiver uses a three-stage transistor amplifier. The first two transistors (BC549C) form the audio signal amplifier, while the third transistor (BD139) is used to drive a headphone. An adjustable potentiometer is included for maximum clarity. The photo transistor should be directed towards the IR LEDs of the transmitter for maximum range. A 9V battery can be used for the receiver circuit for portable operation.

The described circuit functions as a wireless audio transmission system utilizing infrared (IR) technology. The project consists of two primary components: the IR transmitter and the IR receiver.

The IR transmitter is designed to capture audio signals from a TV output. The audio output transformer is crucial in this setup, as it converts the audio signal from the TV into a suitable format for amplification. The low impedance side of the transformer connects to the TV, ensuring a robust signal transfer, while the high impedance side connects to the input of the transistor amplifier configuration. The two-stage transistor amplifier, utilizing transistors such as BC547 and BD140, boosts the audio signal sufficiently to drive the two IR LEDs in series, which emit infrared light corresponding to the audio signal.

The IR receiver captures the infrared signals emitted by the transmitter. It employs a three-stage amplifier configuration, where the first two transistors (BC549C) amplify the received infrared signals, converting them back into audio signals. The third transistor (BD139) acts as a driver for the headphones, ensuring that the audio output is at an appropriate level for listening. The inclusion of an adjustable potentiometer allows users to fine-tune the audio clarity, enhancing the listening experience.

For optimal performance, the photo transistor in the receiver should be oriented towards the IR LEDs of the transmitter, maximizing the effective transmission range, which can reach up to 6 meters without additional optics. The range can be extended further with the incorporation of lenses and reflectors. The power supply for both the transmitter and receiver can be provided by a 9V battery or mains adapter, offering flexibility for stationary or portable applications.

This project represents an effective solution for wireless audio transmission, allowing users to enjoy TV audio without disturbing others, making it particularly useful in shared living spaces or for individuals who require a discreet listening option.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. 🔗 External reference