In this project, I’ll show you how to make a Simple IR Audio Link circuit that can wirelessly transmit audio signals. This infrared audio link can send audio signals across short distances. In the Transmitter section, the audio signal to be transmitted is applied to the transistor’s base. To listen to the broadcast signal, an 8 speaker or headphone is attached at the reception part.
Outline
- Introduction
- Simple IR Audio Transmitter and Receiver Circuit Principle
- IR Audio Transmitter and Receiver Circuit Diagram
- Components Required
- Transmitter Section
- Receiver Section
- Simple IR Audio Link Circuit Design
- How to Operate IR Audio Transmitter and Receiver Circuit?
- Simple IR Audio Link Circuit Applications
- Simple IR Audio Link Circuit Limitations
Introduction
Bluetooth and RF Communications are the key technologies in wireless audio, which is already a technically sophisticated subject (although most commercial audio equipment works with Bluetooth). Designing a simple IR Audio Link Circuit may not be advantageous in comparison to existing technologies, but it will undoubtedly be an educational experience in wireless audio transfer.
The reason for this is that, unlike Bluetooth, IR is a line-of-sight communication system, which means that both the transmitter and receiver must always face each other without obstructions. Furthermore, the range may be limited compared to that of a normal Bluetooth Wireless Audio device.
None the less, for the purpose of understanding, let me design a simple IR Audio Link circuit using easily available components.
Simple IR Audio Transmitter and Receiver Circuit Principle
In this circuit, the primary premise is IR communication. Infrared (IR) is exclusively utilised for low-range line-of-sight communications. In the electromagnetic spectrum, infrared rays have wavelengths that are longer than visible light wavelengths. These infrared rays are invisible to the naked eye, but they can be seen with a digital camera.
Infrared sources, such as infrared lasers or LEDs with particular wavelengths, are used in most IR communication systems. IR communication uses vacuum, atmosphere, and optical fibres as transmission media. Finally, photo diodes or photo transistors will be used in IR communication to detect IR rays.
This detector’s output signal is quite low, and it may not be able to drive the speakers. As a result, we’ll utilise a basic amplifier to boost the signal. The speakers can be driven by this increased signal.
IR Audio Transmitter and Receiver Circuit Diagram
Components Required
Transmitter Section
- 9V Battery
- Resistor – 1KΩ X 2
- IR Transmitters (IR LEDs) – 2
- BC548 NPN Transistor
- Connecting wires
- Breadboard
Receiver Section
- Photo Diode
- Resistor – 100KΩ
- POT – 100KΩ
- Capacitors – 0.1µF X 2, 10µF, 47µF
- LM386 Audio Amplifier
- Connecting wires
- 8Ω Speaker
- 9V Battery
- Breadboard
Simple IR Audio Link Circuit Design
The IR audio link circuit is separated into two sections: one for the transmitter and another for the receiver. The transmitter is powered by a 9V battery. The audio signal is applied to the base of the Q1 through a 1K resistor in this example.
The IR LEDs D1 and D2 are driven by the transistor Q1. The incoming audio signal is modified and transferred as infrared signals.
The photo diode receives the transmitted infrared signals. The audio signal is now converted to an electrical signal before being sent to the LM386.
The LM386 is a basic Audio Power Amplifier IC with a 1W maximum output power. It can drive both 4 and 8 speakers, and I used a tiny 8 speaker in this circuit.
I used 9V batteries to power the transmitter and reception portions in my arrangement. In the receiver part, you can use a Photo Transistor like the BPW77NA, BPW85, PNA1605F, or PNZ154 instead of a Photo Diode.
NOTE: In case you are using a Photo Transistor, the circuit at the receiver end changes to the following.
How to Operate IR Audio Transmitter and Receiver Circuit?
- As shown in the circuit diagram, connect the transmitter and receiver individually at first.
- Using two 9V batteries, power both the transmitter and receiver portions.
- Connect an 8-speaker to the LM386 Audio Amplifier IC’s output.
- Make sure the distance between the transmitter and the receiver is less than 30cm.
- Using a mobile phone or a music player, apply the audio signal to the transmitter part. You can now listen to the sound from the speaker.
- Disconnect the transmitter and receiver batteries.
Simple IR Audio Link Circuit Applications
- Used in audio communications to transfer the audio signal from one place to other.
- Used in short range communications.
Simple IR Audio Link Circuit Limitations
- This IR audio link circuit works only for short distances
- This circuit is not very practical in the sense that there exists a lot of noise and may require some changes to implement it more efficiently.
