In-Wall Touch-Sensor Double Switch and more...

  • Since first time I heard about MySensors project, I wanted to replace all switches in my house with Arduino-bases remote-controlled smart switches.
    After a few experiments and evolutions, I ended up in a fairly compact smart device which fits even in 1-gang in-wall box and has the following features:

    • Power-connected: device has 110V -> 5V converter on board, so it source the power from the in-wall line (in-wall box need to have a common neutral wire)
    • Has 2 touch sensors which control 2 relays: so it can control 2 lines
    • More Arduino pins are available to connect more sensors (I played with IR motion sensor and going to try light sensors)
    • Through NRF24L01+ module it is connected to Raspberry Pi gateway ( which runs OpenHABian clone of Raspbian (, and MySensors are connected to OpenHAB via MQTT ( - so using myopenHAB account I can control my switches from my phone and using openHAB-to-GoogleAssistant integration - from Google Assistant

    Radio is connected to Arduino using jModule, and the overall breakout was a inspired by HLK-PM01 breakout board by sundberg84 (


    The second wall plate insert is not used here, but I have places where I actually glued another couple of touch sensors which control other switches in the house through openHAB rules or added a motion sensor there.

  • Great work! And thanks for sharing!

    This is very much along the lines of what I would like to do. I also read sundberg84's HLK-PM01 thread many times, as well as many others.

    I am still doing my homework, which I have been doing for literally years already. However more recently, armed with some confidence gained by studying the work of much more knowledgeable people here in this wonderful community (like yourself) I started ordering some parts and experimenting finally. 🙂

    Could you say a little more about those physical switches? I guess they are just some sort of plain flat switches that engage the metal pads on the touch sensors? Does that work well?

    Is that a US wall box? It looks like it...

    It would be great if you could post this up on, so that I (and I am sure others) could further study the design.

    Again, great work!

  • @trs-80 touch sensors are those:
    It is sensitive enough to detect touch through the decorative plastic plate

    yes, I am planning to add it to openhardware, just need to dedicate time for that 🙂

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