Aqara T1 hack: smart hook
Maker Dillan Stock turned an Aqara T1 Door Sensor into a ‘smart hook’ that detects towels or keys by sensing magnet/weight changes and integrates with Home Assistant for automations like routine reminders (x.com). It’s a cheap, DIY sensor tweak that shows how small sensors can enable practical automations in bathrooms and entryways (x.com).
The hook’s internal mechanism uses a spring‑loaded sliding assembly that shifts a small magnet relative to the Aqara T1’s reed switch, with the T1 PCB seated in a custom 3D‑printed cavity. (thestockpot.net) Stock settled on a two‑spring arrangement so users can remove one spring to reduce actuation force, and he enlarged the hook’s travel to overcome the reed switch’s “stiction” (different engage/disengage distances). (thestockpot.net) The finished build, excluding a 3D print, comes together with just a couple of screws and the salvaged T1 board and is estimated to cost about US$15 in parts. (thestockpot.net) His Home Assistant automation starts a 20‑minute timer once his morning alarm has fired; if the hook remains in the “open” state when the timer expires, his system sends a phone notification. (thestockpot.net) If the notification is ignored the automation can escalate to an audible alarm played through household speakers. (hackster.io) The Aqara T1 (model DW‑S03D) used in the project communicates over Zigbee 3.0, runs on a CR1632 coin cell with roughly two years’ battery life under typical use, and lists a maximum detection distance of 22 mm. (aqara.com) Stock previously repurposed the same T1 PCB for recessed door sensors, a related DIY project covered by Hackaday on Feb. 10, 2026. (hackaday.com) Home Assistant users attempting the same mod should note active community reports that the Aqara T1 can present a permanent “closed” state when paired via the ZHA integration, an issue tracked on the Home Assistant GitHub issue thread. (github.com)
