Simple Infrared Wireless Headphone Circuit

Anyone can make personal wireless headphones by designing this circuit!

In order to transfer the sound it uses infrared or invisible light signals rather than a cable.

This enables users to move freely while listening and even control them remotely and also by adjusting the volume or switching tunes.

What is a Infrared Headphones Receiver Circuit:

Receiving wireless audio signals delivered by infrared light is the main use of an infrared IR headphones receiver circuit.

Infrared headphones are wireless headphones that receive audio signals from a source like a TV or audio system using infrared technology.

The receiver circuit which captures the supplied signals and converts them back into audible sounds is an essential part of the headphones.

Circuit Working:

Parts List:

Make use of both the IR headphones transmitter and the IR headphones receiver.

Use headphones that have a 600Ω impedance.

The visible light filter in the BPW41N and BP104 is centered at 950 nm at 25°C.

Considering the simplicity of the IR headphones receiver concept audio distortion at a distance of 3 to 4 meters and under normal lighting conditions ranged from 1% to 2% which is proper.

How to Build:

To build a Simple Infrared Wireless Headphone Circuit following are the steps to be followed:

Find the Components:

• Based on the requirements needs select the proper infrared photodiode.
• Make sure the headphones are suitable with the receiver and check their impedance.

Create the circuit:

• Construct a simple circuit using components for impedance matching and if necessary a photodiode amplifier.
• Use a filter that will focus on the infrared spectrum and block out visible light.

Put the Circuit Together:

• Use a breadboard or a PCB to construct the circuit.
• As shown in the circuit diagram connect the parts.

Connect the transmitter for the infrared headphones:

• Connect the transmitter and receiver of the infrared headphones.
• For efficient signal transmission be sure the alignment and line of sight are correct.

Source of Power:

• Connect the circuit to a suitable power source.
• Check to see if the power supply fulfills the needs of the components.

Testing:

• Under normal lighting conditions test the receiver at an proper height of three to four meters.
• Use the proper instruments to measure audio distortion.

Modifications:

• Adjust the circuit as necessary for best performance.
• To get the desired audio quality change the amplifiers gain or other settings.

Last Testing:

• To guarantee the IR headphones receivers stability carefully test it through a range of situations.

Records:

• For future reference check the connections, final circuit design and any modifications.

What is a Infrared Headphones Transmitter Circuit:

An infrared headphones transmitter circuit is a circuit that uses electricity to wirelessly send audio signals to infrared headphones.

The transmitter circuit which enables wireless transmission of audio signals from a source to the headphones is an essential component of an infrared wireless headphone system.

Circuit Working:

Parts list:

The transmitter makes it possible for headphones to connect optically through infrared.

Three infrared LEDs are energized by transistor T1 current and the current level is fine tuned using P1 preset.

When operating at 9V this infrared headphone transmitter uses about 60mA of current.

The adapter ground should be kept far from the audio signal ground in order to avoid current reactions through the LEDs.

By positioning the LEDs at various angles and adding reflectors behind them the optical link which is relatively directional can be improved.

The best input audio level for this infrared transmitter is between 100 and 200 mV which offers 1.2 to 2.4 meters of coverage.

We have provided the infrared receiver schematic for this particular infrared headphone transmitter.

Formula:

The general formula as follows is sometimes used to calculate the voltage gain (Av) of a Field Effect Transistor FET amplifier:

A_v = −g_m ​* R_L​

where,

• g_m is the transconductance of the FE, which is given by g_m = 2_ID / V_GS − V_th​
• I_D is the drain current of the FET.
• V_GS is the gate source voltage of the FET.
• V_th is the threshold voltage of the FET.
• R_L is the load resistance connected at the drain of the FET.

Reasoning is used:

Gm of transconductance:

This value shows how much the FETs output current changes in response to changes in the input voltage of gate source voltage.

It measures the gain of the FET amplifier.

Resistance to Loading (RL):

This external resistor is connected to the drain (or output) of the FET amplifier.

It controls the voltage gain of the amplifier.

How to Build:

To build a Infrared Headphones Transmitter Circuit follow the below steps for connections:

Find the Components:

• Select proper infrared LEDs, a preset P1 for current modification and a transistor for current polarization T1.
• According to the circuit design choose resistors, capacitors and other electronic parts.

Create the circuit:

• Construct a circuit schematic which includes the audio input, current adjustment and current polarization components for the infrared LEDs.
• If the choice is to use reflectors than decide where to place them.

Put the Circuit Together:

• Use a breadboard or a PCB to construct the circuit.
• As indicated by the circuit diagram connect the parts.

Connect the audio input:

• Connect the source devices audio input to the transmitter circuit.

Source of Power:

• Connect an external power supply or a proper battery to the circuit.

Modifications:

• To change the current level through the LEDs use the preset P1.
• For best results fine tune the circuit.

Testing:

• Use headphones and an infrared receiver to test the transmitter.
• Verify the sent signals range and audio quality.

Conclusion:

The infrared wireless headphone circuit offers the level of remote control features together with wireless music enjoyment.

The design finds use in situations where having the freedom to roam about and controlling audio playing has important features.

Depending on the particular needs and characteristics that the user or designer needs this circuit design may differ.

References:

Wireless headphones applications