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  • Wireless IR Headphone Transmitter

  • Created: Mar 12, 2014

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Description

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Summary

Infrared headphones can be used for listening to music or television cordlessly. The headphones utilize a transmitter that connects with audio cables to the audio source, such as a home entertainment center. The transmitter utilizes light-emitting diodes (LEDs) to direct a focused beam of invisible pulsating light towards a receiver built into the headphone set. The pulsations act as ON/OFF signals that are translated digitally by the receiver into audible sound waves. Most infrared headphones have an effective range of about 30 feet (~10 meters) or less, and require a clear line of sight between transmitter and receiver.


Sound comes out of the stereo system through audio cables and into an infrared transmitter. The transmitter turns the sound into a series of pulses. The pulses work like bits in a computer, digitally capturing the sound information. These pulses are then sent to an infrared LED.


For the transmitter side, an audio input from PL1 frequency modulates the VCO section of a HEF4046BT PLL chip. The VCO output drives Q1, a switching transistor. Q1 drives two IR LEDs. The signal produced is around 100 kHz, FM carrier VCO sensitivity is around 7.5 kHz/V.


See also: Wireless Headphone Receiver

6 Comments


piyush26

What is the no. of IR led transmitter? Regards, PIYUSH

Posted: Mar 08, 2016


NXP

Good day Piyush. The part number of the IR LED is LTST-C190KRKT.

Posted: Apr 05, 2016


Binary_Captain

what is the point in ir headphones? your receiver would have to be in a position to receive the IR signal at all times. That would surely mean that you can not move your head to much and must be within a certain angle of the IR led in the transmitter? however this could be used for speakers where they do not move. the signal could travel a fair distance but any object or person that blocks the signal would still make the speaker receiving the signal void. Please tell me if i am getting this wrong. Cheers Binary_Captain

Posted: Feb 08, 2017


electrix

I believe you are getting it right. Though if the source directs its beam towards a point with almost 0% probability of obstacles, e.g. ceiling, then that point can work as a hub to transmit to the speakers or other hubs (horizontally), which will be able to transmit vertically to the speakers, further reducing the possibility of interruptions.

Posted: Dec 01, 2017


StevenJGreenfield

Is there a reason you put the inputs on the right and the outputs on the left?

Posted: Dec 08, 2017


StevenJGreenfield

IR headphones are not good for listening while working in a garage or around the house. They are good for sitting at a desk or standing at a workbench where there is a clear line-of-sight between the transmitter and receiver. Having had to work with wired headphones, I can tell you that it is a huge pain. They get caught on you and other things. Even staying in a limited area, wireless is fantastic. Put the transmitter up high and the receiver on the top of the headphone band. Looking at the matching receiver circuit, replace the 51k resistor with an inductor around 30mH and you can put more PIN diode receivers in parallel, aimed in a circle. That is how many good Laser Tag receivers work.

Posted: Dec 08, 2017


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