HC-SR501 PIR SensorWelcome to AAC!
What sort of fan? Mains driven? 12V computer fan? ....?
Which PIR sensor?
Links to datasheets for the fand and sensor would be helpful.
What 'automatic' functions do you want?
Any other suitable PIR sensorThe PIR won't detect the presence of a human, only the movement of a human. If the human is sitting still the PIR won't know they are there.
There have been lots of threads on these forums related to detecting (or in many cases, counting) humans in a room. It's never straightforward.Any other suitable PIR sensor