I'm looking for a distance sensor that can reliably measure if someone is within about 10 ft of it. A digital proximity sensor might work too, if I can pretty reliably change its max distance by playing with the input voltage. Cheap is the name of the game here, but it does need to work. I've been looking at the HC-SR04
, but a couple of commenters said it only worked for them up to ~60 cm, while others said it worked up and beyond 10ft. Any suggestions? -- I'm looking at ultrasound because I will be using it at school where there are several Wi-Fi hotspots and a ham radio club, I don't know how much noise this'll cause an IR sensor.
I will be using this in a lab where the space directly in front of the sensor will be clear for at least 20 ft, but there will be some tables to the side. I was thinking maybe I could put some kind of tube around the sensor to narrow it's detection width. Something like a toilet paper roll or a disassembled flashlight tube. Do you think this'll work or will it be likely to always go off because it's reading the tube?