February 2019

MIDI Ultimate Synthesiser

This fully-featured analogue synthesiser has a performance comparable with many commercial instruments, but can be constructed by anyone who can identify components and solder them neatly and methodically. Access to a range of test equipment (digital multimeter, oscilloscope, frequency meter, variable PSU) is also desirable but not entirely essential.

The MIDI Ultimate is a large project with 700 components but, with care, success is readily achievable. All parts, both individual ones and in kit form, will be available from Soundtronics, a UK-based company specialising in DIY synth building and who can also supply the front panels and hardwood case.

In Part One this month, the synthesiser’s range of modules are explored and a parts list is given. Construction of the MIDI Ultimate starts next month.If you want to have a go at building a satisfying analogue synthesiser, this series is for you, so don’t miss it!

Arduino MP3 Player

This project is built from an Arduino MP3 shield, housed in an Altronics Mega Box (see last month) to make a neat and tidy MP3 player. As an added bonus an IR remote control can be used.

Last month we described the features of this very sophisticated speed controller designed for small induction motors and explained its operation in detail.  In Part 2 the parts list, fully-illustrated construction and testing details are provided along with some guidelines for proper use.

This is an improved and updated version of the original Silicon Chip design and includes PCB improvements, up-rated parts and revised software.

WARNING! This project is suitable for very advanced and experienced constructors only. This circuit operates at dangerous voltages throughout. Most parts operate at mains potential or higher. Do not attempt to build it unless you know exactly what you are doing and are very experienced with working with high-voltage circuitry.

Australian supplier Altronics have a kit for this project: Cat K6032. This kit still uses the 20A IGBT bridge specified in the original version of the IMSC, rather than the 30A version. While that is theoretically adequate, it’s safer to use the 30A version. You could buy the kit and the 30A IGBT bridge and subsitute it, but be careful to get the right part (there’s one with a different pin-out and a slightly different code).

Note for UK readers: £1 = AU$1.79 approx and international orders are free of GST.

Using Cheap Asian Electronic Modules
Part 13: Motion Sensor and Soil Moisture Sensing Modules

This month we look at two low-cost modules from Elecrow, a Doppler radar motion sensor and a soil moisture monitor for gardens and pot plants. Both of them can easily be interfaced with an Arduino or Micromite.

New hands-on series! Make it with Micromite

Introducing the Micromite, the brilliant microcontroller that is extremely easy to program and use. External hardware can be hooked to its input/ output pins and the device has built-in BASIC that is easy for beginners to work with.

A parts list is given in readiness for creating a Micromite-powered “Keyring Computer” used in subsequent editions.  If you want to make a start with Micromite, this series is just the thing, so be sure to check out Part One of Making it with Micromite now!

Teach-In 2019 – Powering electronics
Part 3: Linear Voltage Regulators

The all-important subject of voltage regulation is examined in the latest part of our tutorial series dedicated to power supply circuit design. This part starts with simple Zener circuits before moving on to linear voltage regulator applications. A simple variable voltage power supply project is then described that can be built on stripboard.

Please Take Note
The circuit shown in Fig.2.18 (page 43 of January EPE) is incorrect. The two secondary windings should be in parallel and not in series (the corrected circuit diagram is on page 50 in the February 2019 issue). The stripboard wiring layouts (Fig. 2.19) are correctly shown.

Audio Out
Low-level power supplies in audio systems (Part 1)

This month our audio electronics expert explores some  design methodologies and techniques for improving the reliability and power dissipation ratings of power-related circuitry associated with audio amplifiers.

PIC n’ MIX

The basics of building circuits with surface-mount devices (SMD). Our PIC micro expert explains many of the benefits and pitfalls of using these super-miniaturised components, and he offers an actual example of migrating a breadboard design to a PCB using SMD, based on his Spectrum Analyser project (EPE April – July 2018). Design considerations are explored this month, ready for a PCB to be created the modern way, using the services of an online PCB manufacturer.

Also in this issue:

• Techno Talk – the menace of cold callers and the problem of blocking them
• Net Work  – Internet shopping trends from China. Daigou shopping, and will Britain have a Singles Day?
• Circuit Surgery – this very highly regarded column answers a reader’s query and lays bare the theory and principles of summing amplifiers
• Max’s Cool Beans – Max offers a 21st Century take on the good old Nixie tube
• Electronic Building Blocks – applications for a cheap and cheerful digital panel meter.

Next month

Teach-In 2019 (Part 4): switched-mode power supplies; 10-LED bargraph; Earthquake Early Warning Alarm; Low-cost Electronic Modules (Part 14); MIDI Ultimate Synthesiser (Part 2).