PIR Sensor (Rev B) [555-28027] Reduce cool-down time?

sandman

I'm trying to sense when people walk into a room using two PIR (Rev sensors; so I can tell when they are entering and leaving.
The logic behind it isn't the issue, my problem with the PIR sensors is when they first detect a hot body, they give a signal for the first instance a hot-body is detected but then they will stay lit for another ~3 seconds, during which time they will not detect additional hot-bodies entering the room. Is there a way to reduce the cool-down time between first detection and the sensor resetting?


TL:DR
Can I reduce the cool-down time of the PIR sensors after they first sense a hot body?
If so, how?

Thank you.

GordonMcComb

You might sample a Rev A sensor, which work a little differently. Its jumper sets whether you want to trigger repeatedly (when triggering stops there's no movement), or trigger once during continuous movement. Either way, the differentiation between two people entering the room with only a fraction of a second between them might be a tough nut to crack. Worth a shot, though.

This notion of "cool down" time is a bit of a lark, though. PIR sensors don't sense heat as much as they sense change of heat across a pair of detectors. The relative temperature of the sensed object doesn't matter; it's the difference between the two that counts. That's why these things can point to a still-hot asphalt driveway in the evening, and yet detect cooler-bodied people walking up to the house. The on delay is something in Rev B sensors, which I assume was meant to make them a little easier to use. I don't know of a way to adjust it.

-- Gordon

sandman

Sorry when I said 'cool-down' I didn't mean it literally; more along the lines of 'resetting time'.
Thanks for your suggestion though, I will look into Rev A and see if can satisfy my needs.

Thanks again!