The hardware is consists of an Arduino microcontroller (here an Arduino Uno R3) and a pre-wired soil moisture sensor module. The soil moisture sensor module , built around the LM393 comparator, gives ...

At the heart of the circuit is the OS25B10 transmissive optical sensor with phototransistor output (OC1). Next is the venerable LM393 dual comparator chip (IC1) configured as a simple Schmitt trigger ...