>First thing to decide is your range and IR immunity. If your range is
short,

Also be aware of the light frequency.  Most IR emitters seem to be 880nm.
But I believe all those TV type receiver modules are optimized for 940nm.

When you select phototransistors, photodiodes, emitters, and modules, make
certain they are all optimized for the same frequency.  I just spent several
months beating my head against the concrete and speak from experience.

Jay

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