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  • Wireless IR Headphone Receiver

  • Created: Mar 12, 2014

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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.

The headphones pick up the light with a receiver and turn it back into sound. The receiver has an infrared CDS cell, which produces a pulse of electricity every time infrared light lands on it. The cell is designed to pick up the particular frequency of light produced by the transmitter, so it is not disturbed or thrown off by other light. A small computer inside of the receiver takes these pulses of electricity and turns them into an audio signal. This audio signal is then amplified and sent to the headphones themselves, which play the sound.

For the receiver side, a photodiode D1 feeds high gain IR remote control preamp IC, a CA3237E. U2 is a PLL FM detector tuned to around 100 kHz. The detector output is amplified by U3 and it can drive a speaker or a set of headphones.

See also: Wireless Headphone Transmitter



What is the latency of the audio transmission?

Posted: Oct 31, 2016


I'll answer that ... the latency should be inconsequential, not much more than if you simply ran the sound through a few signal stages. The transmitter is not digitally encoding anything, and the receiver is not digitally decoding anything. It is just simple FM frequency modulated. So the latency should be on the order of the top end of the frequency response of the entire signal chain.

Posted: Dec 08, 2017


Replace R3, 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. Put the transmitter up high and put the PIN diode receives on the top of the headband of the headphones.

Posted: Dec 08, 2017



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