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 NXP Semiconductors


  • 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

3 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


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