January 2016 Issue

A summary of this month's contents.

Isolating High-Voltage Oscilloscope probe

This low-cost project is designed to allow you to use your oscilloscope to observe and measure a.c. mains and other high voltage waveforms with confidence.



It has high-voltage opto-isolation built in (>10 GΩ 500V) so your scope can take safe mains measurements involving connections to live or neutral. Three attenuation factors are available (10:1 100:1 and 500:1). Input resistance 2.0M || ~10pF.


Surface mount design needs good soldering skills


High-energy Multi-Spark CDI (Part 2)


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.

In this follow up article we give the assembly details for six different versions to suit your car’s trigger source. Not recommended on 6-cylinder or V8 engines without attending to the HT lead separation (see article).


  • Reluctor pickup
  • Points triggering
  • Hall Effect or Luminition
  • Engine management triggering
  • Crane optical pickup
  • Piranha optical pickup


Transformer winding and installation techniques are also described.


This circuit produces an output of up to 300V DC and can deliver a severe or even fatal electric shock. High voltage design suitable for experienced constructors


The Currawong Valve Amplifier (Part 3)

The final article describes the Currawong Valve (vacuum tube) amplifier’s IR remote volume control, also details of the essential acrylic safety cover and the final setting up routines.



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.


Also in this month’s issue:


Mike O’Keeffe, our PIC microcontroller expert, offers a mini home-grown Christmas tree, with PIC-powered LEDs adding some seasonal cheer.


Max’s Cool Beans

Max progresses with his Cunning Chronograph LED Clock and muses about its coding and practicalities.


  • Circuit Surgery – Our in-house surgeon Ian Bell offers a very comprehensive walk-through of the applications of Darlington transistors and an in-depth analysis of the issues surrounding their use
  • Techno Talk ponders the potential for Internet-aware cars being subjected to hacking or terrorist attack
  • Practically Speaking – Robert Penfold’s workshop series explains how best to handle static-sensitive components to avoid damaging them
  • Audio Out - Jake Rothman  our audio enthusiast outlines a variety of audio filters with practical examples included.
  • Electronic Building Blocks – Julian Edgar adapts a budget-price opto module to provide a snap-action switch
  • Net Work – EPE’s Alan Winstanley looks at a £20 Android HDMI dongle that converts a TV or monitor into a useful Android-powered computer, and explains how to get rid of the “Get Windows 10” popup.


Next month

6-digit Retro Nixie Clock (Part 1); CGA-to-VGA Video Converter; Car Engine Spark Energy Meter. Contents may be subject to last minute change.


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!



Source code and project artwork 0116.zip

Updated 4/12/15


Audio Out PCB Jan 2016 pcb0116.zip



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Starting this month we reminisce on what EPE was doing a decade ago.


The January 2006 issue of EPE was the first in our new style, printed in full colour for the first time and on a brighter, whiter paper.


We marked the semi-retirement of EPE's Dave Barrington and John Becker. Projects published included a 'Tiptronic style' gear indicator for cars, a Sunset light-activated switch, the PIC Ambilux novelty LED display, a current clamp for multimeters and Teach-In 2006.



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.

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