Control an AC Load with a Microcontroller, Arduino or Raspberry Pi

Playing with the mains voltage can be deadly, so proper isolation techniques and safe working practices are very important. Besides emphasizing these lifesaving things, this article also explains in detail how to apply them when building an AC load controller or light dimmer with a well-designed PCB. The device itself can be connected to a microcontroller, but also to an Arduino or a Raspberry Pi board.

Wireless doorbells have been around for many years, but they have limited range. Besides more pleasing sounds than a loud DRRRING from a wired bell they do not really offer much more. Connecting a doorbell to your Wi-Fi network makes things way more interesting. Now suddenly the old button can send email when someone is at the door and you can “hear” it almost anywhere on the globe.

This is one of those projects that many people dream of building, but few actually do all the way. Admit it, you too have thought at least once about automated curtain openers in your bedroom, yet I have only once met a guy who had really done it. This system spouts water at cats to chase them away. I’m gonna build me one of these too, but against pigeons.

Sometimes a project is given such a name that you (read: me!) do not immediately know what it represents or what it does, an ‘Earth Listener’ for example. The description of the product, however, makes things much clearer: ‘The Earth Listener from Velleman is an Arduino-based sensor module that can measure multiple environmental variables in order to indicate the air quality’.

Volumio is a popular audio player app that runs on multiple platforms, and the Raspberry Pi is one of them. This project lets you add remote control to your player in a cheap way by using low-cost 433 MHz transmitter and receiver modules that are easily found online. Besides being suitable for Volumio, you can add the remote also for other applications.

Cheap, powerful and equipped with Bluetooth and Wi-Fi, the ESP32 has quickly become a popular development platform for homegrown IoT applications. Here is one that transforms an ordinary PIR sensor into an almost intelligent, communicating entity. This alarm may be less suited for people who check their email only once a month.

New technologies often find applications in rather unexpected domains. Take for example LoRa, Sigfox and similar IoT technologies. While everybody is working on IoT temperature and humidity sensors for their homes, the real problem is to know if a rodent has been trapped somewhere deep down inside a large building or industrial site. The goal is, of course, to avoid sending out a maintenance engineer to check empty traps.

A good part of humanity loses precious night rest as a result of snoring or snoring bed partners and/or roommates. The Elektor Snore Shield tries to improve the lives of snoring victims (active and passive). Can you improve the Snore Shield and help people sleep better? The best solutions will be rewarded!

Every time Elektor offers a project using Nixie tubes or VFDs, it’s a success. For a bit of variation, we looked for and found something a bit more exotic. Like this original new project for a clock which uses, for the hour and date, pinball score wheel displays. Guaranteed spectacular! When you watch it, the soundtrack will not go unnoticed either.

Inspiring people, that is what we try to do here at Elektor. It doesn’t always work, but when it happens, and we hear about it, we feel that warm glow of happiness grow inside our bodies; a glow quite similar to the one that appears when drinking mulled wine (a.k.a glühwein) in December (or any other alcoholic beverage any time of the year). This week’s project combines inspiration & creativity, Raspberry Pi and mulled wine into an original Christmas decoration.