Adafruit analogue light sensor breakouts adafruit 2748 the adafruit als pt19 analogue light sensor breakout has a high rejection ratio for infra red radiation which makes its spectral response very similar to that of a human eye its output is an analogue signal which is proportionate to the brightness of the incoming light all you have to do is apply power 25 to 55v dc and read the analogue outputsupplied as an assembled and tested light sensor board plus a strip of 01in header pins f