NTE30116 Tinted Blue 5mm Infrared LED Emitter (940nm) SM0038 Photo Module for PCM Remote Control System (38kHz) The principle of this setup is somewhat simple and self-explanatory. In this circuit, ...

The IR sensor array, which on the palm-sized vehicle consisted of just a handful of components, evolved into a PCB-backed bar nearly 0.5 meters wide. Potentiometer tuning was a fiddly affair, but ...

The part list consists of one Arduino, two resistors, and one IR emitter. That’s right, an emitter. When an LED (IR or otherwise) is reverse biased it can act as a light sensor.