Regular readers may be relieved to know that I’m done writing about my trip to Athens, and are back to the occasional series of ‘Neil reviews cheap Zigbee devices from AliExpress’.
Earlier this month, I reviewed Zigbee window sensors, and this time I’m reviewing a Zigbee PIR motion sensor. PIR stands for ‘passive infrared’, and senses changes in infrared light to detect motion. It’s used in most motion detectors for burglar alarm systems, but you can buy sensors such as these for home automation too. In my case, I’ve fitted one to the top of our cellar stairs, to turn on a light in the cellar when motion is detected.
It’s pretty small – about an inch across – and runs on a single CR2450 battery (provided). You also get a sticky pad to attach to surfaces, and a couple of tools for opening the battery flap and for resetting and pairing it. It’s compatible with Zigbee2MQTT.
In terms of configurability, you can adjust its sensitivity, and its keep time. The keep time means that it remains in the ‘occupied’ (i.e. motion detected) state for a given number of seconds after motion was last detected. If you have a motion activated light, this prevents the light constantly flashing on and off.
As with the window sensors, you can also buy these devices from Amazon (sponsored link) if you need them quickly, but again they’re significantly more expensive than AliExpress.
To make the light turn on and off, I have automations set up in Home Assistant. I also bought a Zigbee smart light bulb for the motion sensor. Ideally I would have just bought one that switches on and off, but the cheapest one I could find is a colour changing dimmable one. Which is overkill for a cellar light, but hey, it was cheap. Indeed, the motion sensor and light bulb collectively cost less than £9.
