and blue components of the light that correspond to maximum reflectance, then you know the color of the object. Their sensor uses a four-lead RGB LED, but we suppose a Neopixel could be used as well.

[Fjord Carver] brings together an RGB LED and CdS Photoresistor to make a color sensor ... usually have a very wide swing of resistance when exposed to varying levels of light sensitivity.

If you’ve ever suffered from dry, irritated eyes or struggled to fall asleep after a long day of staring at your computer, you may have been tempted to purchase a pair of blue-light-blocking ...