Hello friends! Today we will build an intelligent energy-saving demonstration using an Arduino Uno, two doorway sensors, an LCD and controlled loads. The idea is to count completed entries and exits, then switch the model room's loads according to that count. The interesting part is not simply turning a relay on. We need to recognize direction, handle an interrupted crossing, avoid counting the same person repeatedly and decide what to do when the count becomes uncertain. We will develop those rules before looking at the complete program. This is a controlled educational demonstration. Two narrow beams cannot reliably count a crowd or guarantee that a real room is empty. We will use low-voltage demonstration loads and make the limitations visible rather than treating an imperfect counter a ...