Locating Wayward Wires

Which way do the wires run? This conundrum regularly faces electricians working in older buildings and do-it-yourself enthusiasts alike – in other words everyone who enjoys (?) doing work in his or her home and garden. Sometimes finding concealed cable runs is far from easy, which is why we are discussing ways and means of locating these hidden copper wires even when they are non-continuous (interrupted).

Do you want to measure not only electrical signals but also optical signals? Then you need an optical probe that converts light intensity into voltage fluctuations that can be evaluated by an oscilloscope. This article shows how to build such a probe yourself inexpensively.

The Capaci-Meter is a capacitance meter with a retro-style ‘Dekatron’-type arrangement of LEDs to represent two digits. It is not designed to be an accurate measurement instrument. Instead it is aimed at establishing if a capacitor is close to the desired value, especially when it is difficult to read the values printed on the capacitor.

Many projects with a microcontroller inside have to display something. In the past, 2-line text displays were common and sufficient, but today graphic LCDs (or OLED displays) are increasingly used. There are several libraries for displaying attractive graphics as well as for touch operation. LittlevGL is a library under the liberal MIT license, which can be easily adapted to various displays and controllers. In this article, we demonstrate the whole thing using an ESP32 board and a touch LCD that displays data from a weather station.

This project controls the brew time of a tea bag in hot water. The mechanics are controlled electronically, and the electrical energy required comes from contemporary energy-harvesting technology, specifically, from the temperature difference between ambient air and the hot water. Meaning batteries (dry or rechargeable), or even a power adapter, are redundant in this project.

With the compliments of the Elektor Editorial and Labs teams, here is a 'fresh' article presented free of charge to all Elektor e-zine subscribers. This time we have author Werner Möhrle discuss his temperature recorder based on an Arduino Uno and a DS1631 sensor, along with a Sketch that, remarkably, doesn't use any libraries!

With the compliments of the Elektor Editorial and Labs teams, here is a 'fresh' article presented free of charge to all Elektor e-zine subscribers. This time we have author Willem Tak discuss an upgrade to an earlier project publication. Willem was prompted by non-availability of a few, let's say, key components. We really like reader's contributions describing how published projects get enhanced, updated and tweaked so here goes with suggestions for new components, and software to put in the 2018 "Multi-Timer".

Raspberry Pi 4 B released on 24 June 2019 and became an instant hit. The new Raspberry Pi 4 is the latest version of the small single series board computers developed and produced by the Raspberry Pi foundation.

Once again, Sensirion trailblazes innovation in environmental sensing to create healthier and more productive environments for people. At this year’s Sensor+Test 2019 in Nuremberg and SensorsExpo 2019 in San José, the expert in environmental sensing, Sensirion, is announcing the SCD40 – the first miniaturized CO2 and RH/T sensor that fits in a space of just one cubic centimeter.

Don’t let the wide range of available low-pressure sensors be intimidating. Because of the range, there will likely be a sensor, or combination of sensors, to meet most application requirements. The key is to know your requirements and constraints first.