A Stereo IR Wireless speaker system built with these modules. This photo was made using IR photography. Note the LEDs appearing as bright points. They are invisible to the unaided eye but bright in the near infrared region
This is an infrared audio receiver that receives audio information modulated on an infrared beam. The PC board on left is the receiver and a set of AA batteries power the receiver. This entire assembly mounts in a plastic meter case
This is the IR transmitter board, shown with four IR LEDS mounted for use as a transmitter. The LEDS may be mounted in optics or a reflector assembly to control the beam and coverage area
The IR receiver board contains all the receiver and audio circuitry and will run from 9-12 volts DC (6 to 8 AA cells). It will deliver up to 1 watt of audio to directly drive a loudspeaker. The photodiode may be mounted off the board in an optical assembly (Lens or parabolic mirror) to increase range.

Internet http://www.northcountryradio.com