To My Readers



If this is the first time you're visiting my blog, thank you. Whether you're interested or just curious to find out about PCB reverse engineering (PCB-RE), I hope you'll find something useful here.

This blog contains many snippets of the content in my books to provide a more detailed overall sampling for my would-be readers to be better informed before making the purchase. Of course, the book contains more photos and nice illustrations, as evidence from its cover page. Hopefully, this online trailer version will whet your appetite enough to want to get a copy for yourself.

Top Review

I started doing component level repair of electronics with (and without) schematics more than 40 years ago, which activity often involves reverse-engineering of printed circuit boards. Although over the years my technical interests have shifted into particle beam instrumentation, electron microscopy, and focused ion beam technology fields, till this day——and more often than not——PCB repairs have returned multiple multi-million-dollar accelerators, FIB, and SEM instruments back to operation, delivering great satisfaction and some profit.

Many of the methods described by Keng Tiong in great details are similar to the approaches I've developed, but some of the techniques are different, and as effective and useful as efficient and practical. Systematic approach and collection of useful information presented in his books are not only invaluable for a novice approaching PCB-level reverse engineering, but also very interesting reading and hands-on reference for professionals.

Focus on reverse engineering instead of original design provides unique perspective into workings of electronics, and in my opinion books by Keng Tiong (I've got all three of them) are must-read for anybody trying to develop good understanding of electronics——together with writings by Paul Horowitz and Winfield Hill, Phil Hobbs, Jim Williams, Bob Pease, Howard Johnson and Martin Graham, Sam Goldwasser, and other world's top electronics experts.

Valery Ray
Particle Beam Systems Technologist

Wednesday, April 19, 2017

Component Classifications (Part 3)

Generally, passive devices have no functional gain or control over voltage or current, their controlling function is basically linear as in the case of a resistor. Active devices on the other hand has the ability to electrically control electron flow to manipulate and transform a signal's properties. For a circuit to be considered electronic, it must contain at least one active device.

Diodes and Zeners



A diode, by definition, is a two-terminal non-linear device that works on the p-n junction principle that exhibits forward and reverse biasing characteristics. There are many types of diodes, from the common rectifier to the varactor, the light-emitting to the photo-laser, and the step recovery to the zener, etc.

So what is the difference between a diode and a zener?

While a diode operates on the forward voltage region and may suffer catastrophic failure if subjected to voltages that exceed its reverse breakdown limit, the zener can safely operate on the reverse voltage region. In other words, while a diode conducts current in only one direction, a zener, by virtue of its heavy narrow junction doping, can conduct current in both directions with the ability to maintain a stable voltage in the reverse bias condition. This makes the zener ideal for applications such as voltage references in comparator circuits and voltage stabilizers in low-current circuits.

As you'd probably realized by now, unlike the axial-lead diodes, SMD packages can contain more than one diode per package type, such as the BAV99 example just mentioned. Things can get really tricky, however, when you work on PCBs with many of these SMD type components present, so it's good to download a copy of the SMD Codebook and keep it handy for quick reference.


Ps: While there are many editions of free SMD Codebook online, readers who buy my book will get a copy of the SMD Code Reference Book, which contains over 500 pages listing of more than 23,000 SMD type component markings.
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