Review on Waveshare Digital LTR390-UV Ultraviolet Sensor (C) Ultraviolet Ray Sensing Ambient Light Intensity Measuring Direct UV Index Value Output I2C Bus by Nina Lucero

This UV sensor works perfectly. It also works to detect blue and UV LEDs. You can hold it up to different light sources to see if it emits UV radiation. I tested the sensitivity by pointing a UV flashlight at the sensor and turning the dial (potentiometer). There seems to be a difference when it is (carefully) turned fully clockwise. The sensor puts out a tiny voltage, so it needs a fairly bright light source to work. To convert the analog output to a true UV Index value, find the current UV Index for your zip code on a weather website, then take some readings outdoors with a sensor and compare them to the published values. This is enough to detect low, medium and high UV levels.