November 2021

This month’s highlights

Dual Battery Lifesaver

This small circuit board (70 x 32mm) is designed to protect rechargeable batteries from being totally discharged – especially useful if you accidentally leave something switched on. It can work with devices that operate from a single battery or two separate batteries. It passes through 3.6-15V at up to 5A per channel and has a quiescent current measured in the low microamps. Discrete components, easy to build.

USB Super Codec (Part 3)

Having introduced our new USB sound card or ‘SuperCodec’ in Parts 1 and 2, in the third part this month we put it all together and get the project up and running. The project’s software-related aspects are also described.

The project contains a number of surface mounted devices and good soldering skills are necessary to construct this project successfully.

Thermometer Calibrator

Many cheap and cheerful digital thermometers cost only a few pounds and although their displays may resolve to 0.1°C, seldom are they that accurate. This simple low-cost thermometer checker uses a semiconductor temperature sensor that requires no calibration itself; simply read the output voltage using a DVM and compare against the thermometer readings to show you just how accurate your thermometer really is.

I/O Expander Modules

These add-on modules were designed specially to provide I/O expansion capacity to a microcontroller project. They all use I²C serial bus and three variants are described based on different chipsets so there is bound to be one to meet your needs. If you’ve run out of I/O pins on your project, this expander module could be just the solution!

Colour Maximite 2 (Generation 2) – Part 2

Last month we introduced the new, and extremely powerful, Colour Maximite 2 Generation 2 computer , a retro home computer capable of giving an impressive performance. This month we turn our attention to assembly of the main PCB – and don’t worry, the surface-mount aspects are already sorted for you. We follow on with initial testing procedures and running an initial Welcome demo tape. An optional USB mouse controller is described next month.

Note certain components mentioned are currently in short supply and it may a while before they become readily available from their manufacturers again.

Audio Out

Our expert audio circuitry enthusiast embarks on his latest project, a high quality Analogue Vocoder (Part 1).

  One example of a vocoder effect will be found in the music track ‘O Superman’ by Laurie Anderson, visit

Also in this issue:

  • The Fox Report – Barry Fox comments on the latest virtual reality demonstrations
  • Barry Fox’s Tekkie Pix – on John Sargrove, the father of automated mass production in WW2. More technical press photos can be found at
  • Techno Talk – explaining all those international approval symbols that appear on modern electronics
  • Net Work—semiconductor shortages, a portable SOS messenger and the latest hydrogen trials
  • Circuit Surgery – an in-depth paper on capacitor dielectric absorption
  • Max’s Cool Beans – steampunk-compatible fasteners and making ‘robot eyes’ with Max’s ‘SMAD’  multi segment colour displays, and more practical coding tips
  • PIC n’ MIX – Part 8 of the PIC18F development board, adding Wi-Fi capabilities to this weather station and working with the Internet dashboard.

In next month’s issue:

Digital AM/ FM/ SW Receiver; MINI Digital Volt/ Amp Panel Meters; Balanced Input & Attenuator for the USB SuperCodec (Part 1); KickStart – direct digital synthesis. Contents may be subject to change.

November 2021 files for download -


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