Den – Installing a light switch

In a previous post, I covered the Den Automation Smart Hub setup. Next up, I’d like to cover the installation and setup of their 1 gang light switch.

I ordered four of these, to cover the rooms upstairs in my house. I’ll post the processing I went through to install one of the switches.

WARNING – CHANGING THESE SWITCHES REQUIRES EXPOSE TO MAINS VOLTAGE, WHICH IS EXTREMELY DANGEROUS. TAKE THE NECESSARY PRECAUTIONS. I AM NOT RESPONSIBLE FOR ANY INJURY THAT MAY RESULT. REMEMBER TO ISOLATE YOUR SWITCHES AT THE FUSE BOARD. IF IN DOUBT, GET AN ELECTRICIAN!

The humble light switch. Please ignore the filth of my walls!

Having turned off the lights at the fuse board (see my stern warning above) I removed the face plate.

A simple switch. Brown is the live and the blue is the switched live. The box is earthed too.

Den Switches require an earth connection to function (I’m guessing they use the voltage across live and earth to charge their capacitor, keeping the leaked current so low it doesn’t trip the RCD – clever sods!)

The Den switch has four inputs, Earth, Live, Switched Live 1 and Switched Live 2.

Den provide a small Earth cable that acts as an extensions, so I wired that into the backing box.

I added the Den earth extension into the earth connector of the backing box.

The backing box on my switches isn’t deep enough to accommodate the Den switch, so I had to use the provided spacer. I hung that over the wires.

I then connected it up and screwed it in place (using the longer screws provided by Den)

The Den Switch after installation

After restoring the power at the fuse board, I was able to turn the light on and off. Pretty useful to know that still worked šŸ™‚

To pair the switch with the Hub, I launched the Den App and, under the settings part, opted to add a new light switch.

The app starts to guide you through the process, similar to the Hub setup
A soft light starts to blink on the switch after holding down the button

The pairing process took about fifteen seconds.
Customising your new light switch

Name the light using their own names or create your own
Add it to a new room….
Choose an existing room
Done

The installation process was quick and painless.

Unfortunately, after I’d installed mine and I was cleaning it down, I noticed it didn’t quite fit correctly:

An imperfection in the switch prevented it sitting flush against spacer

I wrote to Den’s support email and, whilst it took two days to get an actual response, they dispatched a replacement which I received the next day. I swapped them out and the replacement was perfectly fine. I would have liked a faster reply from support, but they did resolve the issue without any question (I just included the above picture).

I swapped out four light switches upstairs, so I can now control all the bedroom lights.

Firmware update messages are kinda useless as you don’t know the room!

One point of complaint that I still has is that one of the switches hasn’t updated its firmware yet. Three updated to the 1.3 firmware without any issues, but the forth is still stuck on the 1.1 firmware. I need to contact support about this.

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Den Automation – Unboxing

It’s been a long time in the making, but Den Automation finally started fulfilling their pre-orders earlier this month. I received my pre-ordered items, an order I placed in March 2018, last Monday. I’ve been looking forward to getting my hands on some Den gear since I first heard about the company in 2017. I love to dabble in home automation and the idea of a light switch that was a drop in replacement for a “dumb” light switch sparked joy!

I should point out that I’m an investor in Den Automation, holding a few shares that I bought through Seedrs.

So, what did I buy?

  • Smart Hub (required to control everything else)
  • Four One-Gang switches
  • One Double Gang socket

Den, as a thank you, threw in a remote too. That was a nice surprise.

The packaging looks nice and reminds me a little of Nest product packaging, with a nice sleeve surrounding the box.

The Smart Hub

The Smart Hub is the brains of the operation.

Opening up the Smart Hub Box.
The contents – The Hub, Some instructions, an Ethernet cable, power cable, adapter and mounting screws.

The hub itself was a little smaller than I expected. It was very light in weight. If I’m honest, it does feel a little cheap, but I’m only comparing that a Google WiFi unit that I had close at hand. That said, it didn’t feel flimsy and the connectors were solid when I plugged in the power and Ethernet cables. I was surprised that the power connector on the hub itself wasn’t USB. I was also surprised the Smart Hub required an Ethernet connection.

UPDATE: 28 Jan 2019 I’ve installed four light switches and they feel solid now that they are on the wall. After a few operations I couldn’t tell the difference. The Hub is also in position and I’ll hopefully never touch it again, so comments on its weight seem silly now.

The Smart Switch

This particular device was the reason I love Den’s concept. Smart WiFi switches are nothing new, but most are either touch based or require a neutral connection (like Sonoff’s offerings). I like the old fashioned rocker switch. Familiar and reliable. Lightwave RF have offered WiFi switches for a long time, but I’ve never taken to their push button design.

An extra earth wire, additional screws, spacing plate and switch.

On lifting the switch out and flicking the rocker a few time, I have to admit I felt a little disappointed. The rocker lacked the weight I’m used to. I handed it to my wife and she agreed. Of course, it’s easy to criticise something like this and, weighting aside, we agreed to reserve final judgement until I’d installed them. Having something that can flick itself on and off is *never* going to as solid as something manual.

The spacing plate is provided in case the backing box isn’t deep enough. it was well packaged, being hidden under the insert. This meant it didn’t get in the way of the Switch itself and the box was opened.

The insert contains a message to slip the box over. Wasn’t very obvious! I knew the spacer was included and lifted the insert out in search of it. That message probably needs to more obvious?

I read some of Den Automation’s early tweets and the use of Earth is crucial to the operation of their light switches, so I’m glad the included some extra cabling.

The Smart Socket

I ordered a Smart Socket just to try it out. I currently use one Sonoff Smart Plug to controlling power to my TV. It’s used a lot (the standby on my ten year old telly draws more wattage than I’d care to admit). The sockets in my house are brushed steel downstairs, but the sockets behind my TV aren’t visible, so I think this is a natural place. It will mean I turn off both my Apple TV and the TV itself.

Smart Tags, screws, the spacer and the double socket

One of the things that Den have done in this space is something I personally find very clever. They have created a concept of Smart Tags. These little tags fit over a plug and can be used to identify an appliance or item.

The socket included four smart tags

I haven’t tested them out yet, but the idea is as following. You pair a tag with an appliance i.e. a hair dryer. When you plug it in, the socket *knows* what’s plugged in. The example Den give is around hair straighteners and a person leaving them plugged in and turned on. I think it’s innovative, but requires every socket in your house to be a Den Socket (I don’t know if they have a patent on this idea).

As a neat touch, Den also put a Smart Tag on the power supply for the Smart Hub. That made me smile!

The Smart Hub power adaptor came fitted with a Smart Tag

The Remote

As a gesture of goodwill, for the numerous delays in shipping, Den chucked in a free remote.

It seems to just be an on or off type deal, but I don’t know anything beyond that. I assume you can pair it to one or more sockets or switches in the Den App. Once I get everything setup, I’ll be sure to write more about it.

Summary

The packaging was nice and well presented, but the items themselves felt a little cheap. It’s hard to explain. I have put this feeling down to the type of plastic and how it feels. The weight of the items also feeds into that feeling too. I know it’s pointless to try and gauge quality by the weight or feel of something and I’ll reserve judgement until I’ve installed them and used them.

I’ll do another post on the setup once I get more time.

I’m happy to answer any questions you might have. I think it’s fantastic that a small UK startup are producing products like this and that they have finally shipping is a testament to their hard work and determination. I’ve played no part in the development of the product, nor do I personally know anyone involved, but I can appreciate the monumental effort required to deliver hardware and software, especially consumer facing.

I take my hat off to Yasser and his team.

Project: Water Softener Salt Level Detector

In my house, I have a water softener. This requires topping up with salt at varying intervals, depending on the usage. In the year I’ve been living here, I’ve forgotten twice. Whilst it’s not the end of the world, it does mean that we get some limescale build up on theĀ taps and, more annoyingly, the shower head. I’ve triedĀ a recurring calendar entry to remind me, but the reminds would happen pop up when I was at work, or out and about etc. By the time I got home, I’d forgotten about it.Ā This sort of small annoyance was something I felt could be fixed with a overly complicated, time consuming, technological solution!

The problem

My water softener has a large compartment at the front, which you fill with salt tablets. Overtime, these get used up as the software regenerates itself.

I wanted a way to detect when the level of the salt had dropped to a low level.

How to measure the level?

My first pass at this problem involved using ultra sonic ranging device. I purchased a simple unit that was good for distances up to three metres. More than enough for my needs. To power this unit and make the necessary calculations, I chose a Raspberry Pi Zero, the latest entry to the Raspberry Pi Family. At about Ā£9 it seemed likeĀ a good option to get me started on my first IoT project. To be honest, I bought one on a whim and needed to put it to work!

I connected it all up and, in testing, it worked very well. I went as far as to build a simple iOS app to display the current level (I even build a simple web page with SignalR!!!)Ā  Unfortunately, it was useless when it came to the salt. Ultrasonic works best with flat surfaces and the top of the a pile of salt tables is anything but level! I thought about placing a piece of word or plastic on top of the pile, but this seemed like a hack. Okay, the whole thing is a hack, but I have to maintain some standards!

I went back to the web and started researching how people measure levels like this in real life, coal bunkers and whatnot. They use lasers. I didn’t want to spend any more money than absolutely necessary, so I would need a different approach.

The idea when struck me that I could use a reed switch (one that turns on in the presence of a magnetic field) and a wooden rod with a small magnet on it. The rod would rest of the pile of salt and move downwards, inching the magnet closer to the switch. On paper, this seemed like it would work, but in practice, I didn’t have enough space above the softener for the rod to protrude.

 

img_5492
The initial circuit board with the reed switch

I then had another brainwave. Replace the rod with a piece of string and a weight! The effect was the same, but it didn’t require the space! Genius.

img_5493
Waterproofing the *complex* electronics

img_5494
A lid with the mechanism attached

img_5495
Side view showing the string coming through

I put all the electronics into a water proof box and fed in the USB power cable. I added some LEDs to give me some idea it was working (green indicated my software was running and red indicated low salt). I moved the reed switch to the end of a piece of cable, so I could better position it. Some gorilla tape and a straw (to ensure the string moved unimpeded) and my contraption was complete!

I mounted the contraption onto my softener, replacing the lid.

img_5497

The software is designed to send me an alert once the salt runs low. As tempted as I was to write my own app and host a back end server, sanity prevailed and I just used IFTTT to raise an alert.

img_5498
An IFTTT alert telling me to top up the salt

Summary

The contraption has been in place now for a few months (it’s taken me that long to write this bloody blog post!) and it’s not been a mixed bag. I’ve gotten one alert, which arrived at 3 in the morning. Another time, I just checked the softener on a whim to discover that the salt was low, but the string had snagged and got stuck. I freed it and a second later got the IFTTT alert. At least it proved my python script was reliable.

I’ve put some plastic on top of the wood to ensure the string never snags again and I’m expecting an alert in the next few weeks.

The future?

With version one in place and working, I’ve started thinking about version 2. These are the improvements I plan on making:

  1. Switch to an MCU (Micro Control Unit). The Pi is great, but it’s overkill (running a full OS) and uses much more power than necessary. The NodeMCU board, for example, can be put into a deep sleep, which users very little power.
  2. Replace the breadboard with a PCB to reduce space.
  3. Trigger the measurement at fixed intervals and only notify me when I’m *actually* home. The last part I’m not sure about, but I suspect IFTTT can *know* where you are.
  4. Potentially use an IR sensor for distance measurement. Whilst this would eliminate any moving parts, it would require a hole into the salt holder and I’m worried that water might splash out or onto it.