December 2022

This month’s highlights

‘Hummingbird’ Audio Amplifier


This miniature amplifier might be diminutive but it delivers big sound! It outputs up to 60W r.m.s. into 8Ω or 100 watts r.m.s. into 4Ω.  The design is intended to give a good all-round performance that will make it ideal for multi-channel amplifiers or when using an active crossover, though many more uses spring to mind. The Hummingbird amplifier has overcurrent and short-circuit protection, and a THD <0.008%. The extremely compact PCB carries a transistor design utilising through-hole components throughout, so it should be straightforward to construct.  Requires ±24-40V DC power supply.

USB Cable Tester (Part 2)

^ Selection of LCD screens

This handy gadget will test the integrity and performance of all common USB cables (A-type, B-type, USB C, Mini B and Micro B), displaying the results on an alphanumeric LCD display. It pulse-tests the current at 100mA, 500mA and 1A and can distinguish between power-only charging cables and USB2 and USB 3.2 cables. It can also report faults with individual cable ends, detecting short or open circuits as well. This PICmicro-powered device will be indispensable for IT users with loads of USB cables stashed away — now you can test them all, with ease. It’s also a great first step to take when diagnosing troublesome USB devices. Assembly details, setup and calibration are described in Part 2 this month.

Contains some surface-mount components requiring good soldering skills.

SMD Trainer Board

Are you interested in learning to solder small, surface-mount devices (SMDs) but don’t know where to start? Many projects now use SMD components that need a certain amount of skill and precision for successful construction, so this SMD Trainer Board is an ideal way of getting to grips with identifying and utilising many of these tiny parts. Our SMD Trainer Board hosts a variety of discrete components and integrated circuits, and after successful construction will be rewarded with some flashing surface-mount LEDs! Also we’ve a separate special feature, SMD Soldering Tips & Tricks

SMD Soldering Tips & Tricks

This extra 7-page article offers hobbyists a lot more background guidance and advice for those who are either new to surface-mount tech or would like to brush up their skills or knowledge. There’s a lot of practical advice on offer in this must-see special article.

Make it with Micromite
PicoMite Fingerprint Reader (Part 1)

This month we introduce some basic principles of fingerprint modules.

Audio Out

This month our analogue audio expert starts work on a new single op.amp board optimised for audio applications.

Also in this issue

  • Techno Talk – a battery that can recharge in minutes or even seconds, and trends in quantum batteries!
  • The Fox Report – more from Ofcom’s fatally flawed complaints handling process
  • Net Work – a smartphone app that reads your smart meter data, next steps in the nuclear fusion programme, a look at TP Link’s Tapo smart gadgets and power-monitoring mains adapters
  • Circuit Surgery – Electronically-controlled resistance (Part 4). Our in-house expert continues to explore ‘digipots’, digitally-controlled potentiometers.
  • Max’s Cool Beans – more of Max’s merriment and ruminations about electronics technology and life in general.

Next month:

Multi-channel speaker protector; Geekcreit’s 35MHz-4.4GHz Signal generator; Classic LED Metronome; IR Remote-control UHF convert & range extender.

December 2022 files for download -


    Printed Circuit Boards

    We supply PCBs for all our projects going back to 2013.

    New PE service – Programmed PICs

    Buy programmed PICs for most of our projects.

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