December 2015

This month’s highlights

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 voltage design suitable for experienced constructors

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).

December 2015 files for download -

  • TDR Dongle box artwork

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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