I wanted to automate the lights in my studio: Lights on when I’m working, Lights off when I’m gone. But I’ve discovered that I have a special set of ninja skills: I’m able to sit long enough behind the computer without significant movement to disable the motion detection. Really annoying to have to wave to the sensor for some attention every couple of minutes. (and I don’t want to ramp up the idle period to 15 minutes).
Then I thought it would be really convenient if those car chair sensors to detect people (to put on the seatbelt) where inside the desk chair. Little search on Uncle Ali, and found some universal chair sensors. Great! https://nl.aliexpress.com/af/universal-car-seat-sensor.html
I’ve modded a Aqara window Zigbee sensor to connect it to the seat sensor. It really works great!
I figured I’m probably not the only person with these ninja skills, so here’s a tutorial how to detect seat presence.
These are the parts you need
Use a small flat screwdriver to wedge open the enclosure
Don’t loose the small reset “button” (don’t forget to reinstall if it drops out)
This is the PCB.
Desolder the reed contact (the glass thube). It helps if you add solder first.
Solder the seat sensor wires like this
Cut a hole in the enclosure (make sure you cut the correct side)
Press everything back together and you are good to go!
Pair it with Homey. Invert the contact alarm in the settings and put it on the chair.
The best place is directly under the fabric. But I’ve put it under the seat-cushion. I’m using a game chair and there’s a flat metal plate below it.
If I sit, the seat gets pressed enough to push the sensor for detection. It didn’t detect flawlessly this way, so I added some strips of that sponge isolation tape (that stuff you put on windows to eliminate draft) on the top of the sensor. Now it never failed to detect seat presence under the seat.