These are simple devices, with an infra-red emitter and a photo-transistor, both facing upwards, but work at an unusual wavelength. “These contain both emitters and detectors for 940nm wavelength,” ...
A CNET editor from 2013 to 2024, Ry's beats included smart home tech, lighting, appliances ... cruising a gravel road in his UTV with some good tunes, camping, and hanging out with his family.