https://www.sparkfun.com/mini-photocell.html
This is a very small light sensor. A photocell changes (also called a photodetector, photo resistor, CdS or photoconductive cell) resistance depending on the...
sparkfun electronicsminiphotocell
https://www.instructables.com/Oil-Burner-Photocell-Repair/
Oil Burner Photocell Repair: A common problem with oil fired heating is failure of the flame detector photocell. The cell can get sooted up or fail...
oil burnerphotocellrepairstepsinstructables
https://www.ledsolution.cn/rl03-led-street-light/
seriescecbw