On-board LM393 voltage comparator chip and infrared sensing probe. Support 5V/3.3V voltage input. On-board signal output indication, output effective signal is high level, and the same time the indicator light up, output signal can directly connect with microcontroller IO. Signal detection sensitivity can be adjusted. Reserved a line voltage compare circuit (P3 is leaded out). PCB size: 30(mm) x15(mm).