From now on, the Room Board is going to be shipped with a new PIR (passive infrared) motion sensor:
The reason I went looking for a replacement is that the ELV unit was out of stock for a long time, especially in quantity. It seems to be back now, but I had already found a good alternative.
The unit shown above is nice for a couple of reasons:
- it’s equally low-power, drawing 40..50 µA
- this unit is specifically for 3 .. 3.3V, whereas the ELV unit was running slightly out of spec
- (it officially requires 5..24V, but the regulator brings that to 3V)
- it’s slightly lower on the sensor side (and higher on the component side)
- the sensor seems to be sensitive over a somewhat wider angle
- it’s no longer a kit, no need to solder-in that sensitive PIR chip anymore
I’ve yet to do some serious testing w.r.t. range, but it appears to be ok.
Here are the two sensors side-by-side:
One unfortunate detail is that the pinout is different. Yes, even 3 pins can lead to incompatible variations!
The old sensor has: VCC GND OUT – the new one uses: VCC OUT GND. Besides, I want to connect it to +3V now, i.s.o. PWR.
I solved this by using the other side of the room board, and reconnecting GND slightly differently – i.e. cutting the pin off and rewiring it as follows:
It’s a hack, but it works. The two remaining pins are still enough to keep the sensor board firmly in place.