Building a Connected Cuckoo Clock

I’ve been building up my smart home setup for the last couple of years, and it generates a lot of data – from the cat’s weight, to the humidity in each room, and like any Smart Project full of sensors, the question becomes what do we do with all that data? Graphs and dashboards? Push notifications? Disembodied vocal announcements using the Sonos?

While cuckoo clock on a yellow wall. The clock has a ring of light around the dial and a red light shining onto the pendulum.

In the early 2000’s a company called Violet, released the Nabaztag – an internet connected Rabbit, with extremely expressive ears and lights on its belly. It wasn’t something I could afford at the time, but ever since, I’ve been interested in the idea of ambient or glanceable devices – devices that fit into our environment and let us know important information without directly calling for our attention.

I decided to try to use a cuckoo clock as the foundation for an ambient device project.  I had this plan that I could add a light to the bottom of the clock that would create a nice glow on the wall behind it. I also planned to take control of the cuckoo mechanism, so rather than chiming on the hour, it could chime whenever I wanted (if I wanted a somewhat less passive notification). While putting together an order of the components I would need, I came across a ring of 20 RGB LEDS that would fit nicely behind the clockface, so I added that to the plan too.

Now, I have far too much respect for mechanical clocks to go tearing into beautifully made mechanical clock, so I started on eBay with a battery powered, plastic quartz clock. I was actually pretty impressed by this clock in its default state, it was reasonably attractive (if you’re into modern minimalist cuckoo clock styles) and the cuckoo sound was decent. My only real complaint was that the hands were a really long way forward of the clock face, which didn’t look so great if you weren’t looking at the clock directly from the front.

The Teardown

I started pulling the clock apart to see what I would find, and it was pretty interesting. The chime & cuckoo are in their own module, connected to a clock & pendulum module. I was amused to find that when I further dismantled that clock module, it contained a standard clock unit inside it – complete with normally inaccessible AAA battery connecter. Because sometimes, even in mass production, its easier to repurpose an existing item then built it from scratch.

The quartz clock module, showing the AAA battery connector

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Internet of Poop: How (and Why) I Built a Smart Litter Tray

Naturally, we want our pets to be as healthy and happy as possible, and just as with humans, one valuable metric to know is their weight. Knowing the weight of our four-legged friends, not only helps us to verify that they have a healthy amount of body fat, but can also can be used to detect things early on that may need medical attention. As they cannot speak to us and tell us when don’t feel well, it is our duty to listen to all of the different signals we have to understand their wellbeing.

Photo of a black shorthair cat sitting.

That’s why I wanted to know the weight of my cat, Ellie. Unfortunately, she really dislikes being picked up or handled, even by people she trusts. This means, it’s not possible to weigh her on a bathroom scale, and the only datapoint I have is her yearly examination at the vets. 

I wanted to build something that would fit into her life to track her weight automatically, without any intervention. I decided to modify her litter box, so that on each visit it records her weight.

But WHY, Andy?

Okay I get it; you think it’s weird. So here are the main goals of the project: 

  • Track Ellie’s weight because I want to know how heavy she is without going to the vet
  • Learn something about how load cells work
  • Have fun building a new project
  • (Hopefully) Inspire others to try out new ideas and projects by sharing what I learned. 
  • Track the weight of poops because I thought that was funny. 

The Hardware

Rather than build the whole litter tray from scratch, I decided to build a platform that her existing litter tray would rest on. This platform would contain all the equipment necessary to detect when Ellie was using the litter and start taking measurements.

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How I Made My Bathroom Fan Smart

When I moved into my house, it came with this and old fan in the bathroom to keep the moisture down when you’ve had a shower, the bathroom itself is in the inside of the building and doesn’t have any external walls / windows, so the fan is really important to keeping it dry and non-moldy.

The original extractor worked well enough, but I’ve never really been that happy with it; it’s kind of noisy when running at full speed and has a trickle mode that runs it at low speed all the time – ostensibly this is to keep the room fresh, but in reality, means that the room Is always cold in the winter. It’s also not very well installed – is the case not fully closed on the fan focusing, and when I tried to close it up tightly the fan scraped the inside of the case and made an awful noise.

More recently the humidistat that makes it speed up automatically stopped working, meaning that after a shower the room would stay damp for hours afterwards. I’ve tried taking the fan apart and cleaning it in case it was just dust and grime of the sensor. But that didn’t help, so I set about replacing it. This being 2021 with nothing better to do, I decided to make it smart and control it from software.

After some research, I used a Manrose MF 100T inline fan, looking down the spec sheets, it is quieter, more electricity efferent and moves more air than the existing solution so seems like a great fit.

Photo of installed extractor fan in attic with inlet and outlet tubes.

To control the fan, I used a Shelly 1 relay – I’ve used some Shelly 1 PM relays in a couple of other places that I’ll write about soon, and I’ve so far been super happy with their ease of use and reliability.

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