July 2023

MIDI Spectral Sound Synthesiser

This advanced synthesiser is a full-blown instrument capable of creating rich, detailed sounds. It’s easy to build and can be hooked up to any MIDI-compatible device. This special constructional feature also describes the composition and harmonics associated with different musical instruments, together with an in-depth explanation of waveform synthesis.

Using dual-in-line through-hole integrated circuits throughout for straightforward soldering, it comprises eight PIC and dsPIC microcontrollers that carry out all the ‘heavy lifting’. A near complete kit including programmed dsPICs is available by mail order – details in the magazine

Multimeter Checker/ Calibrator

This useful item of test equipment can verify the accuracy of multimeters, and can assist with the calibration of more expensive meters and adjustment for drift. It provides a 3.3V DC reference ±0.1%, a 1V RMS a.c. voltage reference ±0.5% Uses a PIC microcontroller and digital potentiometer.

Surface mount components are used throughout. Good soldering skills are needed to complete this project successfully.

MOS Air Quality Sensors

We’ve published gas/ smoke detector designs since 1980 that utilised Figaro tin-oxide sensors to monitor ambient air (for example, see http://alanwinstanley.squarespace.com/hobby-electronics/2012/5/3/interview-part-3-great-graticules.html), so this feature article is a long overdue update on current generation MOS (metal oxide semiconductor) type sensor modules. The article outlines some low-cost ready-made modules that can be interfaced with an Arduino Uno.

Kick Start
Part 12: Your first oscilloscope

Our Kick Start series continues with a special feature explaining the considerations surrounding the purchase of an oscilloscope, followed by a detailed walk-through of a ‘scope’s controls and how to get the best out of them. The feature includes plenty of screenshots and photos, together with a summary of sources of new and used oscilloscopes.

Audio Out
Part 2: Potentiometer scratching

The second installment of a practical workshop gives more intensive care to scratchy noisy potentiometer tracks, plus there’s a multitude of practical hints and tips for restorers, and a summary of many of the most popular pots ever made. A vast wealth of knowledge is contained in this article that is a must-read for every analogue audio enthusiast!

Also in this issue:

• Techno Talk – Max muses about the origins and future of artificial intelligence.
• The Fox Report – Barry Fox’s technology column recounts the evolution of the atomic clock, and hits a brick wall when dealing with the press office of the UK’s National Physical Laboratory (NPL).
• Net Work – our Internet column sets up an Internet-aware weather station, more ‘dark patterns’ in Microsoft’s Windows setup program, hits problems trying to use Android Auto, and there’s bad news for PURE Evoke Flow DAB / Internet radio owners.
• Circuit Surgery – how simple diodes are used to provide reverse-polarity protection and switching between power sources
• Max’s Cool Beans – Our assiduous Arduino champ Max continues with Part 7 of his Arduino Bootcamp with more coding for switching applications.

Next month

Wide-Range Ohmmeter, SPY-DER speech and web-controlled surveillance spider robot, 0-110dB RF Attenuator for signal generators; Updated Universal Battery Charge Controller, PAS CO2 Air Quality Sensor Module.