LM393 LDR module for Arduino to detect the level of light/darkness. 

• 1 Photosensitive Resistance module's most sensitive to ambient light, commonly used to detect environment around the device.
• 2 The sensivity of the auto-trigger can be changed or can be read by an Arduino as analog voltage.
• 3 the DO output can be directly connected to a microcontroller, through single chip microcomputer to detect the high and low
• level, thus to detect the environment light intensity changes;
• 4 the DO output can be directly driven out a relay module, which can form a light-operated switch.