The series resistor R1 sets the operating current (and hence the brightness level) of IRED1. The infrared receiver IR1 is only sensitive to light modulated with a specific (38kHz) ... 0 comments on “ ...

If you believe that a PM2.5/10 sensor can also detect O1, NO2, SO2 then go right ahead and market it as an “Air Quality” sensor. I look forward to the law suits.

A low-cost (~$100), do-it-yourself (DIY) ultrasonic water level sensor/datalogger has been designed, constructed, and tested for use in education, citizen/community science, and research settings. The ...