I have previously published the first part of this topic which is about interfacing with a RF-based home security system. Later on, I found a relatively cheap 220V relay that works on the same 433 MHz frequency and decided to purchase one from AliExpress to try out. It was a single-channel relay which means it has only one switch. These could be controlled with a key fob, or for advanced use cases, a Raspberry Pi computer that can emit RF signals.

Note that there could be different relays in the market which look and behave different to the one I’ve…


Featured image showing a RF transmitter and receiver against a background of colorful jumper cables

While researching around on how the small sensors on doors/windows and motion detectors work, I found out that they are based on a radio frequency protocol which is typically on the 433 Mhz, 315 MHz or 868 MHz bands. The control hubs that link all of these sensors also operate on the same frequency and usually comes with a key fob that can be used to do things like activate/deactivate it or sound the alarm.


In 2020, when most of us were stuck inside homes, I stumbled upon an old WiFi camera that I had bought back in 2017 from a site with a questionable name. The problem with this camera was that it’s not a closed-circuit system and had to connect to a third-party web service to function which was the reason I ended up not using it. I did a bit of research on the internet and found a custom firmware which prevents any communication with the internet but the downside is that it will stop writing to the SD card. Having the…


දැනුම් දීමක්: මම Orange/Orel සමාගම් සමග කිසිදු සම්බන්ධයක් නොමැති අතර, මෙම ලිපිය ලිවීම සඳහා ඔවුහු කිසිදු අනුග්‍රහයක් කර නොමැත. සියලු විස්තර මවිසින්ම සොයාගත් අතර මෙම භාණ්ඩය මිලදී ගනු ලැබුවේ මාගේම මුදලින් ය.

මෙහි පින්තූරවල සඳහන් වචන ඉංග්‍රීසි භාෂාවෙන් තිබීම ගැන සමාවන්න.

This article is also available in English language.
මෙම ලිපිය ඉංග්‍රීසි භාෂාවෙන්ද කියවිය හැක.

නිවැරදි කිරීම 12/06/2021: මම කලින් මෙහි එන SD card එක 16GB යැයි සඳහන් කර තිබුනා. එසේ කලේ RPiඑක පණගැන්වූ පසු පෙන්වූ නම නිසයි. එහෙත් මම එම කාඩ්පත ඉවතට ගෙන බලන විට එය 8GB එකක් විය. තවද, Perspex යන වෙළඳ සලකුණ වෙනුවට acrylic යනුවෙන් වෙනස් කෙරුනි.


Disclaimer: I am not affiliated with Orange/Orel and they have not sponsored me by any means in writing this article. I have done my own research and spent my own money to purchase the items mentioned herein.

This article is also available in Sinhala language.
මෙම ලිපිය සිංහල භාෂාවෙන්ද කියවිය හැක.

Correction 12/06/2021: I have previously stated that the SD card is 16GB judging by the name shown when logged into the RPi. I have now taken it out and it’s 8GB. The trademark “Perspex” has been replaced with “clear acrylic”.

Recently, a friend forwarded an online brochure for the…

Binesh Amarasekara

Coffee-to-code converter, passionate about art and music

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