Things not to do with PIR sensors

“Hi. I’m Rob. I do stupid things with hardware so you don’t have to”

Today I thought it might be a good idea to see what happens if you try to use a PIR sensor without the plastic dome lens on top. I figured that I’d be happy to sacrifice a bit of sensitivity for a cooler aesthetic. In other words I wanted to get rid of the ugly dome and put the sensor behind a 3d printed panel.

Preliminary tests suggested that this might work, so I designed and printed a case lid and put the sensor behind it. Then it didn’t work at all. I think that 3D printed PLA is probably a bit too opaque to the infra-red signal that the sensor uses. Oh well.