DIY audio jack ir blaster

Mon 28 January 2019

This IR Blaster works with iOS App EzRemote

Theory

The process is based on the fact that the IR key codes are series of square waves at 38kHz of main frequency. The duration in time of the square waves ON and OFF defines the codification of a specific key. By considering a common audio stereo channel (2 mono), it can support max of 22kHz per channel with a total of 44kHz. This means that if an audio stereo channel is created by considering 2 mono channels defined in this way:

-wayChannel #1= sine wave with 19kHz as main frequency and silent for the time duration at which original IR key square wave is zero

-zeroChannel #2= same as Channel #1 but inverted (basically mirrored)

then, it is possible to emulate the Remote Controller with a simple audio player hardware and a very simple dual led transmitter.

Transmitter

This allows you to send IR codes. What you need is:

2 IR Led 940nm 5mm (the typical one present on RC)
1 stereo jack 3.5mm

The connections should be as showed below= Led1 (+) must be connected to Led2 (-) and both to one stereo channel, Led1 (-) must be connected to Led2 (+) and both to the other stereo channel leaving the ground not connected Alt Text

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