help me on importance of using automatic room light

[Richmond]

automatic room light

could somebody please help me on some importance of using automatic room light. the lights come on or off when people enter or leave respectively.
thanks

 

[betwixt]

Re: automatic room light

You need something like a PIR detector. Alternatively, you can wire two sensors inside the doorway and check the outer one operates before the inner one to indicate someone has entered. If the inner one operates before the outer one, someone has left. You could use interrupted light beams for this.

Brian.

 

[Richmond]

Brian
thank you very much for your support. if i wanted to use infrared sensors what about that.