I recently had to build an infrared close proximity sensor that could tell if something was dropped in a parcel delivery drop box. After some searching, I ended up using a microcontroller and a piece ...

LEDs can shed infrared light on low cost, long lifetime sensors to monitor carbon dioxide levels in buildings, suggests Ralph Weir. To most people carbon dioxide (CO2) is a ‘greenhouse gas’, but not ...

A reliable indicator of the air quality in offices, classrooms, or living rooms is the CO2 content. In fresh air, the concentration of carbon dioxide is around 400 ppm. This stands for “parts per ...