I have a PIR motion detector designed to sense if someone is walking towards my house.
In addition to a dial for adjusting PIR sensitivity, this motion detector unit has a photocell mounted to face downwards. The motion detector unit is designed for 24 hour operation so clearly the photocell is NOT for sensing darkness for "night time only" operation.
So what does the photocell do?
Unfortunately I can't test it reliably under light and dark conditions because it is a wirefree detector unit which transmits pulses every few seconds and gives very sporadic responses.
I figure the photocell probably alters the PIR's sensitivity charactersistics in some way. Is this right?
But would the unit be made more sensitive or less sensitive in brighter daylight?