MORE ABOUT Raspberry Pi

How do you power a highly reliable LoRa gateway that can be trusted not to trash its SD card and can be remotely located and managed? With this Power over Ethernet (PoE) powered uninterruptible power supply (UPS). A couple of 25-farad supercaps provide enough backup time to cover ten seconds of power outage plus another fifteen seconds to cleanly shut down the Pi if necessary.

Some people need a thousand words to say something simple and still you have no clue what they’re on about. Others manage to explain a complicated thing in only a few words. This project is probably the project with the shortest description at Elektor Labs, but then again, why use many words when it is all about images? True, there are some illustrations too.

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.

What do ships, factories and security services have in common? Several different and incompatible communication systems to control and secure one site. Indeed, VHF radios, telephones, intercom systems and more are all used together to communicate with the different services, rooms and departments in a building or on a site. Pollux provides a single front-end for all these communication systems.

Who realizes this little project gets a device that monitors & displays the current refrigerator temperature, and that logs the time the door was opened and for how long. Alarms can be set on maximum allowed temperature and door-open time.

For those who want to adjust the volume of the music they listen to with analog hardware but do not want to invest in servo-controlled potentiometers here is a compromise in the shape of a so-called ‘Digitally-Controlled Analog Volume Control’. It has a serial control interface, selectable zero crossing detection and a mute function. This design was intended for use with a Raspberry Pi running Volumio, but it can be used with virtually any audio source. It even adds RC control.

MQTT (Message Queue Telemetry Transport) is a publish-subscribe-based (one-to-one or one-to-many) messaging protocol oriented to communication with sensors. MQTT architecture follows a star topology with one or more clients or nodes, and a central server — the broker — responsible of managing the network and relaying messages. This project describes an ESP8266-based adapter that allows any electronic device having a serial port to become an MQTT node connected to a Wi-Fi IoT network. A broker is built with a Raspberry Pi.

As Editor-in-Chief of Elektor Magazine's German edition I am naturally concerned whenever I hear that we have lost one of our (loyal) subscribers because of content-related issues. The corresponding email (fortunately we don’t get many) was forwarded to me from our memberships department. It was a bit disappointing for me...

When you are looking for a small, stand-alone networked audio player with a touch screen you will mainly find big-ass consumer amplifiers. Those that have network support either have no touch screen or are very expensive. So, why not build one yourself? Based on a cheap Raspberry Pi and a high-end digital-to-analog converter this audio DAC handles 24-bit data, sample rates up to 200 kHz and has a built-in 8x oversampling filter.

The Raspberry PI IO-Box is an open source platform for control and automated test systems. It features a versatile & extendable bus capable of addressing up to 56 modules. The bus supports SPI, I2C, 8-bit parallel bus, and analog (+/-10V) and digital signals. Power supplies (3.3 V, 5 V, +/-12 V and 24 VDC) have not been forgotten. Controllable over Telnet or through a graphical web interface, the PIIOX makes automation and automated testing accessible to everyone.