For a project I needed several PIR sensors and I know Adafruit sells a PIR board for about 10 USD. A description of that board is on instructables
. That is doable, but I needed a few and of course there is also shipping + the mail delivery in my country (western Europe) is notoriously bad the last few years, so I had been putting it off (many other things to do as well).
Anyway, at a local thrift store, I had bought two battery operated LED nightlamps with a motion sensor (2.50 euro each) and while I was reading up on people hacking specific Breeze airfresheners for their motion sensor, these night lamps just did their duty, well sort of till I had changed the batteries a few times as they were pretty greedy for energy and i had forgotten about them.
But then I suddenly realised, Hey these thingies have motion sensors as well and when the batteries had started to leak in one of them I decide it was time for some further dissection.
The night lamp in question is a small casing with the typical white opaque PIR lens, a section with 3 bright LED's, a switch, for On, Off and Auto, and what I presumed was a photo diode, sticking out at one side. Opening the thing went pretty easy, just four screws.
It contained a little PCB with one big PIR sensor and one DIL-16 IC
The IC turned out to be an LP0001. I could find a very brief datasheet in English and the more extensive ones were in Chinese. yet I could figure it out.
I could get a digital signal from Pin 2 and an analogue signal from Pin 12.
The digital signal just indicates something moving yes or no, whereas the analog signal gives info on how close an object is. I am not sure though if the latter is really accurate.
Anyway, I needed a digital signal, but flexible as I am I decided to make a digital as well as an analogue I/O on it and also supply it with a decent 5 volt supply. That is very easily done.
Nightlamps with motion sensor
3 pieces of wire, preferably one of them black and the other two different colors except black or red
1 x 4 wide screw terminal strip
piece of four wire cable at desired length
Materials and tools:
3-4 mm dril