Moreover, the S16-L221D sensor lets you add a light dependent resistor (LDR). It is not very practical in this Grove-mini PIR motion sensor module, especially because of the ‘tight’ PCB artwork. The ...

At one end is an LED and at the other the LDR, and when attached to a glove it provides a finger sensor without the fuss. The amount of light reaching the LDR from the LED decreases as the pipe is ...