Here is OddBot’s next attempt at making a low cost DIY IR tracking system. I really like how he shares his successes and failures during the entire build process. This is a great resource for learning about IR LEDs.

My newest array, with navy blue IR LEDs works better as I’ve gone back to a single phototransistor for the sensor instead of two in parallel. The idea is that fewer lenses are better. The domed end of a LED or a phototransistor is a lens that focuses the light sent or received. The IR LEDs I’m using have a viewing angle of about 30 degrees. Check you datasheet of both LEDs and phototransistor as it can vary.

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