A couple of years ago I knocked up a small sensor to detect if I’d locked my traditional UK uPVC door without installing a smart lock. Back then I had these requirements which I think still hold true:
- UK smart locks are still pretty poor in choice (imo) and are often bulky (conexis is the only one that even resembles a normal handle), most don’t even work with a lift to lock multipoint system. I’m not really looking to physically lock/unlock the door I just want to know the state.
- The sensor must be removable from where it’s installed for easy battery replacement.
- Longevity and reliability. Springs lose their “bounce” and switches have finite lifespans.
- No alterations to the door and the device must not be visible when the door is closed. You shouldn’t really know it’s there. So it needs to be battery powered and no cables/boxes sticking out from the door frame.
V1 has been running reliably for the last couple of years but there was a couple of drawbacks to that design:
- The glass reed switch was quite delicate and over the past 2 years I’ve had 2 spontaneously smash during normal operation. I think the temp swings eventually cause this as there’s no physical contact with the reed.
- It was quite hard to remove the board from the frame to replace the battery once everything was soldered into place.
I’ve spent a little time designing a v2 which I installed on one door earlier this week which hopefully addresses both of those problems. It’s very similar in design given the previous one has been working so well and it’s about as far as my 3D design skills go!
If anyone is interested I’ve put more details and the print files on printables here. It’ll only work for certain doors but it fits in both of my (different) uPVC doors so I suspect there’s some form of standard in the UK at least.
