IR INTRUDER CKT: Infrared LED & Phototransistor Pair 5mm Pair of Infrared LED and Photo diode tuned to IR wavelength IR Transmitter & Receiver Pair Use this 5 mm ir transmitter and receiver pair to build object sensors, color sensors, line sensors, distance sensors, etc. Both the transmitter and receiver are built to work on the 940 nm wavelength. Note: the transparent led is transmitter while the dark blue one is the