Question What kind of motion sensor doesn't detect heat?

[mbrewer22]

What kind of motion detector should I use for the Pi 4, if I only want to detect motion, not heat?

 

[kanewolf]

What kind of motion detector should I use for the Pi 4, if I only want to detect motion, not heat?

Millimeter radar motion sensor. But the desired detection distance is important.

 

[mbrewer22]

I just want to detect if something goes through a four inch hole.

 

[kanewolf]

I just want to detect if something goes through a four inch hole.

But how far away from that four inch hole can you place the sensor?

 

[mbrewer22]

But how far away from that four inch hole can you place the sensor?

The PVC pipe (4" hole), will have a small hole drilled in it about 4 inches from the top. The plan is to place the sensor in that drilled hole to monitor if something passes by it.

 

[kanewolf]

The PVC pipe (4" hole), will have a small hole drilled in it about 4 inches from the top. The plan is to place the sensor in that drilled hole to monitor if something passes by it.

I don't know that you can get a mm sensor to fit that form-factor.

 

[kanewolf]

The PVC pipe (4" hole), will have a small hole drilled in it about 4 inches from the top. The plan is to place the sensor in that drilled hole to monitor if something passes by it.

Is the "something" solid or liquid? Maybe put foil opposite the hole and use an optical reflective sensor. Or an optical receiver and sender on opposite sides.

 

[mbrewer22]

Is the "something" solid or liquid? Maybe put foil opposite the hole and use an optical reflective sensor. Or an optical receiver and sender on opposite sides.

It would be solid. That's something to consider.

 

[kanewolf]

It would be solid. That's something to consider.

Optical sensors are typically used for applications like this. Think of assembly lines detecting product arrival at a station.

 

[ex_bubblehead]

Ultrasonics can also be used. 40Khz+, with range decreasing as frequency rises.

 

[OldSurferDude]

Ultrasonics can also be used. 40Khz+, with range decreasing as frequency rises.

If what is being detected is alive (eg. rat) then it is possible the living thing will be wary of the "noise".

Also, some ultrasonic detectors, like the ones that come in Arduino experimenters kit, don't work so well at close distances.

OSD