May 2022

This month’s highlights

64-key MIDI Matrix (Part 2)

This simple to build but powerful project turns an Arduino into a MIDI matrix costing just a fraction of a commercial one and which can be customised by changing the Arduino software. It supports regular or illuminated buttons and can also be programmed to act as MIDI pass-through, among other roles. Full constructional details were provided in Part 1 last month, and Part 2 explores the software – you can even use it with Android phones and tablets. The article also explains the technicalities of the MIDI protocol. A project that’s a must-read for the MIDI musician.

Digital FX Unit (Part 2)

This digital effects machine creates unique sounds when connected to a variety of instruments, such as an electric guitar, violin or cello, or even the output of a microphone preamp, or within the effects loop of an amplifier or mixer.  The design utilises a digital FX processor chip. There are 15 different effects including chorus, echo, flange, vibrato, wah, reverb and distortion. Each effect has three adjustable parameters. Its heavy duty build is suitable for stage use. Its high input impedance will suit piezo pickups, and it operates from a DC adaptor or battery.

Circuitry and construction were described in Part 1 last month, and we follow up with operating and FX customisation in Part 2 in this month’s issue, showing in depth how you can create and install different effects patches into the project’s EEPROM using the PICkit programmer.

  Surface mount components are used and good soldering skills are needed to complete this project successfully.

High-current Battery Balancer (Part 2)

To preserve long battery life, proper balancing of the individual cells will avoid the risk of overcharging some cells while undercharging others. This High-current Battery Balancer does exactly that: it balances two, three or four series-connected cells or batteries and is suitable for Li-ion, LiPo, lead acid and other types. Each cell or battery can range 2.5V (fully discharged) to 15V, and the project supplies a balancing current up to 2.5A and a charging current up to 50A. It can double as an efficient battery charger or discharger. Circuit principles were discussed in Part 1 last month and constructional details are given in Part 2 this month.

  Surface mount components are used and good soldering skills are needed to complete this project successfully.

Wind turbine for your garden

This project is ideal for environmentally-aware experimenters who would like to try building a mini wind turbine. This handy article describes the use of a small turbine that’s available online, is surprisingly well made for the money (£100) and has a useful output. Our contributor also provides some practical setting up tips, coupling up a battery and controller, and test measurements taken under various conditions.  Just the place to start if you’re thinking of harnessing wind power for some garden projects or lighting!

KickStart Part 8: Introducing the Raspberry Pi Pico

The latest instalment of this series gives a quick-start lead-in to the latest version of the hugely popular Raspberry Pi single board computer, comparing it against the Arduino Nano.

Audio Out: Analogue Vocoder (Part 7): Assembly and Testing

At last we reach the closing stages of the Analogue Vocoder assembly. All the intricacies of installation and interwiring are included along with a multitude of photographs to help ensure you can confidently complete this project.

Also in this issue:

  • Techno Talk How tiny electrical nano generators are being developed for the purpose of healing wounds.
  • Net Work The latest technological news and trends from around the world, Gigafactories, a new SUV from Fisker and developments in electric trucks and commuter planes.
  • Max’s Cool Beans  Max continues to explore and elucidate about an eclectic assortment of electronic applications, including the SMAD animatronic head, an analogue computer called The Analog Thing (THAT) and using the Teensy computer along the way.
  • Circuit Surgery This month our in-house surgeon Ian Bell offers an exceptional discourse on the physics of the Royer oscillator.
  • Electronic Building Blocks Here’s a great beginner’s project, an easy and low cost, easy to build electronic ‘stethoscope’ for diagnosing moving machinery faults on car engines or motors. It’s based on a cheap imported module available to buy online.

In next month’s issue

8 / 14/ 20 pin PIC Programming Helper; Advanced GPS Computer (Part 1); Full-wave Universal Motor Speed Controller; Make it with Micromite (iButton Electronic Door Lock).

May 2022 files for download -


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