Review on 🏃 Highly Efficient DIYmall HC SR501 Motion Infrared Arduino for Enhanced Arduino Projects by Ben Barrington

Probably the most popular IR sensor. It is easy to use and very sensitive. But before you build your project around one, I suggest you set up a test to see if they report detection reliably or maybe overreport. Of the 5 bought, 2 consistently reported people who just weren't there (or maybe reported ghosts?). With all 5 set to maximum sensitivity, I first tested that all 5 detect motion - they did. I then pointed them at the wall and had them report sightings every hour throughout the night when no one was around. One reported an average of 45 detections per hour, another 15, and the other 3 no detections. Apparently 2 has a more vivid imagination than the others. So 2 went in the trash and 3 can be used. I think about $2 each, 3 out of 5 shouldn't be a surprise. I would give 3 good 5 stars and the other 2 1 star, averaging 3.4 but feeling generous and given the low cost I've rounded up to 4.