Stuff to do with Raspberry pi / domoticz etc.

Particulates kill, build your sensor now!

By Atomstar on Wednesday 28 April 2021 19:48 - Comments (10)
Categories: ESP8266, Smarthome, Views: 8.993

One metric still missing from my home sensors is particulates, which are a known health hazard. Although I (secretly) already had a board running for a while, I wasn't satisfied enough to share it. Today, it's ready for sharing, including screaming headline for a change ;)

This board builds on my previous (smaller) design without particulate sensor, and also sports a custom-designed PCB (which you can order here!).

Starting with the end, it looks like:



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Measuring CO2/Temp/RH/Pressure with ESP8266 version 2

By Atomstar on Sunday 3 January 2021 12:21 - Comments (8)
Categories: ESP8266, Smarthome, Views: 6.008

After experimenting a bit, I've made a new iteration of my ESP8266 sensor board, which now sports a PCB design (thanks all fellow Tweakers on GoT!). Some improvements:
  • More compact & uncluttered thanks to PCB
  • Added one (optionally more distant) temperature sensor to prevent self-heating
  • Added deep-sleep cycle to alternatively mitigate self-heating


Update 20210207: made voltage regulator for BME280 requirement more explicit (thanks @ManS-H!)

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Reading out Kamstrup Multical 402/403 with home-built optical head

By Atomstar on Monday 16 November 2020 21:09 - Comments (4)
Categories: Linux, Smarthome, Views: 2.216

Our grid heating meter has been replaced, and since I like to read out meters, I had to replace my read out sensor as well. Here I document how I custom-built an IR / optical head to read out the Kamstrup Multical heat meter using their proprietary protocol.

TL;DR:
  • Get head from using the hal9k.dk reader head (archive) then solder together (22 EUR including shipping in EU, a bargain :) Best to pay with PayPal because banks apparently charge a ridiculous amount to transfer money across currencies.)
  • Connect to an FTDI USB TTL reader (e.g. at tinytronics)
  • Use either use this python script to read out the sensor and push to domoticz, or use my fork to push to InfluxDB or MQTT. Note that the original script seems to use more battery than required (see issue on GitHub repo, being worked on)
  • Useful background info on the Kamstrump Multical meter sensor here (archive) and here (archive).


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Saving 2.0GJ/yr heating by upgrading heat exchanger

By Atomstar on Saturday 18 April 2020 14:03 - Comments (10)
Categories: RaspberryPi, Smarthome, Views: 4.440

Now that I've been collecting data on my house for a while, I've used this to diagnose and fix a heat leak we had in our Eneco district heating ('stadsverwarming' in Dutch) heat exchanger ('warmteafleverset' in Dutch).

TL;DR: Our 20-year old heat exchanger leaked 2.7 GJ/year, after upgrading to a better insulated one this was reduced to only 0.65 GJ/year, saving 2.0GJ or 50 euros per year! The upgrade was for 'free', meaning it's included in the yearly fee of 90 euro/year. It's unclear why Eneco does not do this pro-actively, but you can also request an upgrade if you say the old one does not suffice anymore.

Update: replies disabled because of spam

Heat exchanger yearly heat loss and cost comparison

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ESP8266 sensing CO2 + Temp + RH + Pressure

By Atomstar on Friday 20 December 2019 16:20 - Comments (9)
Categories: ESP8266, Smarthome, Views: 21.788

I've progressed somewhat in home-integrated sensors, and I've established a baseline for a connected home-environment sensor, which I document here.

ESP8266 Lolin d1 mini pro kit back

Update: This design appears to cause some self-heating of the bme280 sensor, leading to a temperature of 2-3 degrees too high. Perhaps mounting it outside the 'case' solves this.

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