Louwrentius

This is a brief article in which I compare the IKEA VINDSTYRKA $50 air quality monitor (PM2.5) with a $290 air quality monitor made by Dylos to see if it's any good.

Context

If you care about indoor air quality, you may already own a CO2 to determine if it's time to ventilate your space a bit¹.

But a CO2 monitor doesn't tell you anything about the amount and size of particulate matter in the air.

Of particular interest are very fine particles, in the "PM2.5" category. Those particles are 2.5 micrometers or smaller in diameter can embed themselves deep inside the lungs and cause health issues.

Both air quality monitoring devices are specifically measuring PM2.5 particulate matter, so that's what we will focus on in this test.

DYLOS DC1100 PRO

I bought a Dylos DC1100 Pro in 2014 as I was quite interesting in the topic of air quality at that time. As I had to import the device, I believe I had to pay around 400 Euros for it but it's now for sale in the US for around $290.

click on the image for a picture of the back

I specifically chose this model because it has a serial port, which allows me to log data and maybe spot some trends. I was thinking about using this data to control my air circulation system in my home, but I never got around to building this.

This device (without serial port) is also explored in-depth by Matthias Wandel, who many of you probably know from his 1.7M subscribers Youtube channel. Tip: he shows the inside of the device.

Note that this video is from 10 years ago and I find it remarkable that the Dylos 1100 Pro is still sold - seemingly unmodified - over the years.

The IKEA VINDSTYRKA

Recently, I discovered that IKEA is now selling the VINDSTYRKA air quality monitor with support for Zigbee. The product is intended to be used with IKEAs range of air purifiers, to better finetune the behaviour of those devices.

The device measures PM2.5 particulate matter and also monitors temperature and humidity. All data is exposed over Zigbee. I've not tested this myself but I wonder how long it would last on a battery bank as it's USB powered.

Due to the low price tag, I decided to compare this $50 device (€40) with my Dylos. I think it's quite an interesting device because the Zigbee support allows you to integrate the device in home automation and log data, if you have a need for that.

Data logging setup

De Dylos device is a bit of a pain, because the measurement values are in particulates per square foot, so I had to find a proper conversion formula, which I found in this paper (page 17). The formula is:

PM2.5 Dylos DC1100 (μg/m3) = (particles > 0.5 μm minus particles > 2.5 μm)/250.

A Raspberry Pi 3B+ is running a Python script that reads the data from the serial port, converts it to PM2.5 values using the previous mentioned formula and transmits it into an InfluxDB + Grafana server.

To log the VINDSTYRKA data, I used a Sonoff Zigbee receiver on a Raspberry Pi 4b+. I installed zigbee2mqtt as a docker container, Mosquitto MQTT server and Telegraf+MQTT-client to submit the data into InfluxDB, which sounds more convoluted than it actually was.

Test method

I just let both devices run for a few days in close proximity to each other in my living room. I kept a balcony door open 24/7. I also created a bit of smoke at some point just to observe how the devices would respond and how much they would deviate from each other. Nothing too scientific, to be frank.

Test result

I've plotted the data from the Dylos and the Ikea device in the same graph and I think the results are quite straightforward. The peak in the middle was my 'smoke test'.

Original click on the image for a larger version

Updated click on the image for a larger version

After a few days I noticed a clear deviation between the VINDSTYRKA and the Dylos DC1100 Pro at certain time intervals. I have no real explanation for this deviation and I can't tell which device shows 'correct' data.

If I try to follow the AQI PM2.5 values for my city, the VINDSTYRKA seems to under report and the Dylos seems to over-report PM2.5 particulate matter.

Evaluation

Based on my test, I think the VINDSTYRKA is good enough, looking at how closely the measurements track the results of the Dylos.

Update September 19th 2023 Based on the new graph data, it seems the Dylos and VINDSTYRKA are less in agreement over absolute PM2.5 values. I'm not sure what to make of it.

As both devices still seem to agree on basic trend data, I would say that they still operate in the same ballpark.

During a cleaning spree I decided that it was time to recycle two old laptops that were just collecting dust on a shelf for many years. Although I didn't have any purpose for them anymore, I realised that the displays were still perfectly fine.

This is the display of my old 13" Intel-based MacBook.

Somehow it felt wasteful to just throw the laptops out, I wondered if it would be possible to use these displays as a regular monitor?

It turns out: yes this is possible and it is also quite simple. My blogpost covers the same topic, with a few more pictures¹.

There is a particular LCD driver board that can be found all over ebay and the well-known Chinese webshops.

These boards cost around $20 and come with most things you need to get the display operational.

The board includes:

1. A small controller print for the on-screen display (center)
2. A high-voltage power supply for the backlight (left)
3. The data cable to drive the actual display (right)
4. Support for audio-passthrough + volume control (right corner)

The board doesn't include:

1. A 12-volt power supply
2. Some kind of frame to make the display and board one easy to handle unit

The board supports HDMI, VGA and DVI for signal input so it should work with almost any computer.

This particular board (M.NT68676.2) is used to power many different panel models. Although the board itself may be the same, it's important to order the board that is specifically tailored to the particular LCD panel you have. The panels seem easy to identify. This is the Macbook LCD panel type (LP133WX1 TL A1):

That TL/A1 part of the model is critical to finding the appropriate controller.

I also have an old Dell Vostro screen that uses the exact same driver board, but the cables are different. Also, it may be the case that the boards are flashed with the appropriate firmware for the particular panel. So I would recommend not to gamble and get the driver board that exactly matches the model number.

To make everything work, we first connect the high-voltage module to the backlight power cable...

...and we also connect the LCD driver cable:

When I connected everything for the first time, the display didn't work at all. It turns out that the board shipped with a second, separate interface cable and I had to swap those cables to make the display work properly.

Power supply

According to the sales page, the board requires a 12-volt 2A adapter, but in practice, I could get away with a tiny, much weaker power supply.

I found an old adapter from a Wi-Fi access-point (long gone) which is rated for just 0.5A. It did power both the board and the screen perfectly. It worked with both the Macbook display as the Dell display so it doesn't seem to be a fluke.

Although I didn't measure actual power consumption, we know that it can't be more than just 6 Watt because that's what the power adapter can handle.

Laptop displays need to be power efficient and that may also make them interesting for low-power or battery-powered projects.

We've only just begun

The display works, but that was the easy part.

The hardest part of this proces (not pictured) was switching the on-screen-display from Chinese (which I don't master) to English. But there is more work ahead.

At this point we end up with just a fragile LCD panel connected to a driver board through a bunch of wires. The whole setup is just an unpractical mess. There are at least two things left to do:

1. Mount the driver board, OSD controller and high-voltage unit to the back of the LCD panel
2. Make some kind of stand

For the old Dell display, I used a bit of wood and hot glue to make a wooden scaffold on which I could mount the driver board with a few screws. It won't win any prizes for sure but it's just an example of what needs to be done make the display (more) manageable.

It still doesn't have a stand but that's for another day. I can imagine that if you own a 3D printer, you can make a nice case with a stand, although that will increase the cost of the project.

Evaluation

What I like most about this kind of project is the fact that for very little money, you can recycle a perfectly fine and usable display that will probably last for another five to ten years. The project takes very little effort and it is also not difficult to do.

You can augment existing hobby projects with a screen and due to the relatively low power consumption, it may even be suitable for battery-powered projects.

And with a bit of work you can make a nice (secondary) monitor out of them. Finally you have an excuse to dust off one of your unused Raspberry Pis that you had to have but didn't have any actual use for.

The thrift-store is cheaper

If your goal is just to get a cheap LCD display, it may be cheaper to go to the nearest thrift-store and buy some old second-hand display for $10. But that may have some drawbacks:

• It will be much larger than the laptop screen
• It is powered by 110/220 volt so less suitable for a battery-powered setup
• overall power consumption will be higher

So it all depends on your particular needs.

Closing words

If you also repurposed a laptop monitor for a project or just as a (secondary) screen, feel free to share your work in the comments.