Tag Archives: amersfoort

Ton Zijlstra

20 May, 2018

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A week ago on my birthday a full halo was visible around the sun. Taken from underneath the 15th century Onze-Lieve-Vrouwe tower in Amersfoort, which is the middle point of the Dutch cadastral grid system, so a key point in Dutch open data.

Ton Zijlstra

19 May, 2018

Oil spill in the water our house sits on. The water authority’s people were there quickly after a neighbour reported it. Mats and barriers deployed. The sun will need to do the rest.

oil spill in the water our house is on oil spill in the water our house is on

Charity by the Litre

Our local gas station has a charity support system instead of a loyalty points system. Early last week I mentioned it to Patrick when we met in London, in a conversation about the various channels charities have to reach people. He asked me for pictures of the system, and today I needed to get some gas for the car, so I took some.

Next to the cash register there’s a large ‘score board’ that cycles through screens showing charities with the biggest donations, or showing different categories of charities and the accumulated donations this year.

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The ‘scoreboard’ of “Tank & Schenk”, which rhymes and means ‘fill up and donate’. The screen here is showing donations to national charities. At the bottom is the total donated, some 33.000 Euro

When you pay, there’s a tablet on the counter where you get the option to choose any local club/charity or national charity to donate your points to. The local list contains all the clubs and associations in the village and city (like the football club, or the carnival club etc), and all museums, music venues and marching bands in the city and region, as well as local charities such as foodbanks, homeless shelters etc.

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My 40 points mentioned at the top can be donated to various categories. Local music, local sports clubs, local cultural institutions, local charities, and underneath (smaller) national charities

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Opening the list of local cultural groups and institutions

When you select a charity you get a thank you screen that also shows you how much that specific charity already received this year.

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This time I selected the museum in the birth home of Piet Mondriaan, which brought the total donation to 78,41 Euro

Measure Your City / Meetjestad.nl

Now that we moved from Enschede to Amersfoort two weeks ago, we are starting to participate in local activities. Today I joined a workshop to build a sensor-hut for the ‘Measure your city‘ project. Initiated by amongst others ‘De War‘, also the people who started FabLab Amersfoort, it is a project to crowdsource measurements to track climate and climate changes inside the city.

The national metereological institute does not measure inside cities as it does not provide data that can be compared with other measurements across the country. By building a dense grid of sensors across the city it becomes possible however to track the emergence of ‘heat islands’ or see how paving over gardens or making them greener influences the city’s microclimates.

The sensor-hub I built this afternoon is based on Arduino, and uses LoRaWan, by means of the The Things Network, to communicate. It currently holds sensors for temperature and humidity, but is prepared to also measure sunlight exposure, rain fall and soil humidity / aridity. It also has a GPS antenna, to capture the location of the device correctly.

It had been a good while since I last handled a soldering iron, but following the ‘fit for all’ building instructions after a while I ended up with a ready device. After loading the right software, it became sensor 51 in the Measure Your City network. The second stage was building a hut for the sensor device, so it measures adequately: shielded from direct sunlight, with air allowed to float around it. This so it matches up with the standards that normal metereological measurements adhere to. After a few hours me and half a dozen or so others had their own sensor-hut to install at home.


the finished device


the hut for the sensors

I haven’t properly installed the device yet: the hut still needs a white coat of paint to reflect sunlight, before mounting it in our garden at about 2 meters height. It is already taking measurements however, and it can be followed through the online database of the network’s measurements. If you look at the current data for my sensor 51, you see it also hasn’t measured its location yet. If that persists as I properly mount it outside, there might be something wrong with the GPS antenna. The temp readings are still in-house readings, and do not reflect outside temperatures.


hello world: first data log entries

I will be running a The Things Network gateway in the near future (when the Kickstarter project delivers) as well, and helped initiate a LoRaWan/The Things Network group in my previous home city Enschede. Building this sensor-hut is the first foray into exploring how I will use that cheap IoT infrastructure currently emerging in the Netherlands. I am looking to add other sensors, along the lines of what e.g. FabLab Barcelona and Waag Society have created with the smart citizen kit, or this project from Freiburg measuring particulate matter in the air.

UPDATE: GPS is working now that the sensor is placed outside. Still need to paint it white though.

Meetjestad.nl sensorhut
Sensor hut in its intended spot in the garden