- 1 IR Audio Transmitter and Receiver Circuit Diagram:
- 2 Related Articles
This article explains you how to design a simple IR audio link which is used to transmit audio signals wirelessly. This IR audio link is able transmit audio signals up to 4 meters. The audio signal which is to be transmitted is applied at the base of the transistor in Transmitter section. An 8 ohm speaker or head phone is connected at the receiver section to listen the transmitted signal.
Simple IR Audio Transmitter and Receiver Circuit Principle:
The main principle in this circuit is IR communication. Infrared (IR) is used only for line – of – sight communications over low range. In electromagnetic spectrum Infrared rays are rays are having the wavelengths longer than the wavelengths of normal light. These Infrared rays are not visible to the human eye, but we can view these IR rays through the digital camera.
A typical IR communication system includes infrared source such as Infrared lasers and LEDs with specific wavelengths. The transmission mediums used for IR communication is vacuum, atmosphere and optical fibers. Finally in IR communication to detect the IR rays we will use photo diodes or photo transistors. The output signal from this detectors is very small and it is not able drive the speakers. Hence we will use amplifiers to amplify the signal. This amplified signal is able to drive the speakers.
IR Audio Transmitter and Receiver Circuit Diagram:
- 9V PP3 DC battery
- 1k resistor (1/4 watt) – 2
- TIL38 IR transmitters – 2
- BC548 NPN transistor
- Connecting wires
- Photo transistor
- BC548 NPN transistors – 2
- Electrolytic capacitor – 1uF
- Resistors (1/4 watt) – 10k, 1k
- Connecting wires
- 8 ohm speaker
- 9V PP3 DC battery
Simple IR Audio Link Circuit Design:
The IR audio link circuit is divided two parts, one is transmitter section and other is receiver section. The transmitter section works with 9V battery. Here the audio signal input is applied at the base of the Q1 via 1k resistor. Here transistor Q1is used to drive the IR diodes D1 and D2. Here the input audio signal is modulated to Infrared signals transmitted.
The transmitted Infrared signals are received by the photo transistor P. The emitter voltage of photo transistor varies linearly according to the audio signal modulated to the Infrared signal. The transistors Q2 and Q3 form darlington circuit, used to amplify the output signal of photo transistor. Now the output signal from darlington circuit is able to drive the headphone or speaker. Here the capacitor C1 and R3 forms a filter, used to reduce the interference from stray Infrared signals.
In this circuit to power the transmitter and receiver sections use 9V PP3 DC batteries. You can use BPW77NA or BPW85 or PNA1605F or PNZ154 as NPN photo transistor in receiver section. For this photo transistor left the base alone. Use TIL38 diodes as IR transmitters.
How to Operate IR Audio Transmitter and Receiver Circuit?
- Initially give transmitter and receiver the connections separately as per the circuit diagram
- Apply power to the both transmitter and receiver sections using two 9V PP3 batteries.
- Connect 8 an ohm speaker at the emitter of BC548 transistor Q3.
- Make sure that distance between Transmitter and receiver sections is below 4 meters.
- Apply the audio signal at transmitter section, now you can listen the sound from speaker.
- Disconnect the batteries from transmitter and receiver
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 theoretical and may require some changes to implement it in practical.