December 2025

Teach-In 2026 by Mike Tooley

World of Wireless – an introduction to Radio and Wireless Technology
Part 2: Introducing RF components and circuits

Our new tutorial series investigates the world of radio frequency circuitry and many of the techniques surrounding radio applications. In Part 2 we examine a simple radio frequency generator circuit and the fundamental principles of the components used, including RF coils and semiconductors. A portable MW (AM) radio receiver is described as a practical project.

Variable Speed Drive for induction motors (Mk 2)
Part 1: Circuit description

This sophisticated update of our Variable Speed Drive offers significant improvements including better cooling, improved safety, higher efficiency and size compared with the original. It provides speed control of 1% to 100% in 0.5% steps, and can operate single-phase shaded pole or permanent split capacitor (PSC) motors, or three-phase induction motors up to 1.5kW.

In Part One this month, a full circuit description is offered along with details of compatibility with different types of motor.

WARNING – FOR EXPERIENCED CONSTRUCTORS ONLY. POTENTIALLY LETHAL MAINS VOLTAGE IS PRESENT THROUGHOUT THE CIRCUIT.  OBSERVE THE SAFETY WARNINGS GIVEN IN THE ARTICLE.

Digital Capacitance Meter

This straightforward piece of test gear measures a wide range of capacitance values, from about 10pF to 10,000uF. It’s based on a PIC microcontroller driving a 128×64 OLED display, and is easy to built using standard through-hole construction and a small number of surface-mount devices.

Battery-powered Model Train

This modification eliminates the need to keep model railway tracks clean to maintain the best performance. By making the model train battery-powered, it no longer needs to draw power from the tracks, making it much more reliable! The project describes a 433MHz transmitter/ receiver pair and a battery locomotive charger.

Audio Out
The Transmanium Fuzz Box
Part 2: assembly

The Transmanium is a fuzz box based on germanium transistors. This follow-up article goes into the nitty-gritty detail of construction, providing practical hints and tips to ensure the best performance and reliability are obtained.

Techno Talk

Global navigation satellite systems (GNSS) are really handy, but how do you navigate if you’re underground and can’t pick up satellite systems? In search of the answer, Max ponders the link between origami, kirigami and fibre-optic gyroscopes.

Weird & Wonderful Arduino Projects
Part 12: storing, updating and displaying scores.

The next phase of construction of a retro games console delves deeply into its digital displays and everything associated with them.

The Fox Report

Barry Fox battles with eBay over missing parcels and photographic proof of delivery. It’s the seller’s responsibility to chase up delivery and courier problems, but the process can be tortuous, as Barry explains.

Circuit Surgery
Measuring the frequency response of a circuit using a PC sound card
Part 3: using op.amps for signal conditioning

This month we look at op.amp circuits in general, with a view of using them in signal-conditioning systems for measuring frequency response.

Net Work – the Internet column

In the last of the regular series, Alan Winstanley updates readers on the likelihood of nuclear power stations being built on the moon, there’s news of the Starship program and how Windows 10 users can gain another year of security updates. Some shortcomings with 12V ‘SAE’ battery chargers are highlighted. Finally we bid farewell to one of the most popular names in electronics book publishing, Babani of London. The Babani  book “The Internet and World Wide Web Explained” was published in 1996 – the same year that Net Work was also created.

You can check the Net Work blog (menu, above) to see a summary and ready-made links

Next month:

High-bandwidth Differential Probe; NFC Programmable Infra-Red Control; USB-Programmable Frequency Divider.