December 2015 Issue

A summary of this month's contents.


High-energy Multi-Spark CDI for performance cars (Part 1)


This capacitor discharge ignition system provides very high energy multi-spark discharge each time the spark plug is fired. It generates a shorter-duration ‘hotter’ spark than traditional ignition and is usable up to 1,000 sparks per second. Produces up to 10 sparks each time a spark plug is fired, depending on engine speed – it can run up to 30,000 rpm in a 4-cyl engine. Suitable for 2-stroke and 4-stroke engines in virtually all internal combustion engines used in cars and motorcycles, and is especially effective at cars running at high RPM. Can be triggered by conventional contact points, Hall effect, optical, engine management or reluctor pickups.

Not recommended on 6-cylinder or V8 engines without attending to the HT lead separation (see article).


This month, principles of circuit operation are described in detail with constructional details following in Part 2 next month.


High voltage design suitable for experienced constructors


TDR Dongle for Oscilloscopes


Utilising the concept of time-domain reflectometry (TDR) with a reasonably fast (20MHz or more) oscilloscope, this TDR Dongle will let you handle a lot of basic cable fault-finding very easily. Useful with many types of cables including co-axial with solid PE dielectric, up to 3km long, it detects any reflections of echoes of a suitable signal that may be created by faults or breaks in the cable. 

This allows the location of such a fault to be pinpointed. Switchable output resistance (50, 75 or 100R). SMA connections. Can be powered from a USB 5V supply. 


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



The Currawong Valve Amplifier (Part 2)

Last month the circuit and presentation of this hybrid valve (vacuum-tube) 10W+10W amplifier were described.  In this month's blockbuster article we describe in full detail the PCB assembly and chassis wiring and with in-depth description of the timber plinth and overall assembly.  Next month, powering it up and checking it out, the optional remote plus the clear safety cover that goes on top.



High Voltages  are present throughout.  Never operate the unit unless the lid is in place.This design is suitable for skilled and experienced constructors only.


Audio Out

Jake Rothman’s insight into everything that the audiophile needs to know about the mechanical construction, benefits and pitfalls of volume controls of every type.



Electronic Building Blocks


A simple off-the-shelf mini voltage booster is tried out this month. By Julian Edgar.


Also in this month's issue:


  • Techno Talk on the modern-day problems of electrical ‘smog’ and ‘dirty’ power lines

  • Net Work – an IP security camera is installed and set up, highlighting typical considerations that users might face with this type of security device

  • Circuit Surgery – the second part by Ian Bell of an in-depth analysis of Analogue Switches and i.c.s that offer this function

  • Interface -  our column by Robert Penfold devoted to PC interfacing techniques, looking at PWM and the problem of legacy (or are they?) ports on a personal computer

  • Max’s Cool Beans –  a conference badge with a twist of Arduino

  • PIC n MIX – our new PIC micro tutor Mike O’Keefe goes back to the fundamentals of designing a new PIC-powered project.  A must-read if you are just starting out in the exciting and fast-changing world of MCUs. Basics and choosing and using them, are discussed this month.


Next month

Isolating high-voltage probe for oscilloscopes; High-energy Multi-Spark CDI (Part 2); The Currawong 10W+10W Valve (Vacuum Tube) Amplifier (Part 3).


EPE is packed with practical electronics projects and theory for the hobbyist. You can order a printed copy of EPE for delivery to your door (worldwide), or try the PDF Version (needs Adobe Reader for Windows), or the Pocketmags for your mobile device. Subscribe now!



This month's file (TDR Dongle box artwork)


PCB artwork


As from July 2013 issue PCB artwork is available free to subscribers only.


Non-subscribers may purchase artwork files for a nominal sum. Please contact our Orders Dept for information or to place an order.


EPE Printed Circuit Boards


We can supply ready-made printed circuit boards (8-digit order codes) to the original design specification via mail order or from our Online Shop.






Review:  Dremel 3D Idea Builder


We get our hands on Dremel’s new 3D PLA printer and Alan Winstanley takes one for a test run. The principle of hardware and associated 3D software are described in this six page review. Should you put one on your Wish List? Read our review and find out!



'Mad Scientist' printed in 3D


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