Switch a small DC motor from an LDR threshold using a properly rated driver, flyback protection, and hysteresis to prevent relay chatter.
A quick rundown of four essential sensors: the LDR light sensor, PIR motion sensor, infrared receiver, and tilt sensor.
Build an RGB lamp that automatically changes color based on ambient light using three LDR light sensors and the map() and analogWrite() functions.
Understand the difference between a bare photoresistor and an LDR module, build the divider, read A0, and calibrate a stable switching threshold.