Electrical Engineering 101 (Third Edition): Everything You Should Have Learned in School…but Probably Didn’t
by Paul McGoldrick
Electrical Engineering 101 (Third Edition): Everything You Should Have Learned in School… but Probably Didn’t
by Darren Ashby, Published by Newnes (Elsevier)
ISBN 13: 978-0-12-386001-9, paperback, 291 pp, $34.95, September 2011
Darren Ashby is the Electronics Product Line Manager at
Icon Health & Fitness
(Logan, UT), manufacturers and purveyors of fitness machines such as
the NordicTrack; he was also one of our EExperts (together with Robert
Ashby) at ChipCenter (the massive content of which – and our previous
incarnation as EDTN – has totally disappeared under UBM Electronics
management) which was the home of my AnalogAvenue. He regards himself as
an EE who has become a “pointy haired” boss and looks to his text as a
way of giving the reader an “intuitive understanding and the tools to
take their electronics education to the next level.” The Third Edition
expands considerably over the previous work.
In Chapter 0 (smacks of digital) Ashby seeks to explain what
electricity is all about, looking at atoms and electrons, conductors and
insulators. He also gives a fairly complicated analogy of energy to
work.
Chapter 1 opens with a lesson after my own heart: the importance of
units! You can solve any piece of mathematics, but unless the units
track to your working you have solved nothing. Going on there is a
comparison of electrical components to physical equivalents, such as
resistors to friction, inductors to mass, and capacitors to springs.
Ashby also introduces a concept he calls intuitive signal analysis which
is his way of describing how he looks at a circuit and breaks it down
into manageable chunks. That works fine with the majority of progressive
circuits but as soon as you incorporate feedback, clamping, and even
the self-start circuits you will find in power supplies it becomes too
much of a guessing game for such analysis. Ashby puts forward six
fundamental equations, which he then details in Chapter 2, Basic Theory:
Ohm’s Law, voltage divider rule (still Ohm’s Law, Darren), capacitors
impede changes in voltage, inductors impede changes in current, series
and parallel resistors (Ohm’s Law, again), and Thevenin’s (sic) theorem.
The latter, as he correctly points out, could be replaced with Norton
which, as a current model, is much easier for virtually all
semiconductor models in ICs, etc when voltage sources can rarely be
deemed as ‘clean’ of any impedance considerations.
Chapter 2 also covers capacitors and resistors in series and parallel
as well as ac generation, reactances, and the essences of low-pass and
high-pass filters. An explanation of magnetic fields is a little
confusing as he suggests that current can flow in an incomplete circuit
but charges are well covered in capacitive electric fields. Ashby then
invites into an understanding of transfer functions including a ‘metric
converter’ of Km (sic) to mile and Ohm’s Law which are neat segues into
feedback and gain loops.
Partially Conducting Electricity is the subtitle of Chapter 3 (Pieces
Parts) with a jump into semiconductors and simple explanations of N
(sic) and P (sic) doping. With the characteristics of a diode graphed
the author misses the major point of telling the reader which way
current conducts – that is which is forward and which is reverse – in
the p-n device. We also have a current “flow across” moment in the diode
and a couple of “current applied” moments in the extension of two
diodes to a transistor’s physical arrangement. He then explains the
transistor – both pnp and npn – used as a switch and gets into linear
amplifiers, albeit to excuse himself because “setting up linear
amplifiers can be a bit of a trick” and that op amp use is better! HFE
(sic) variations? Really? Continuing on with FETs Ashby almost offers
them as a form of super BJT… A paragraph on PCBs is followed by a “list”
of additional parts, which is actually a brief descriptor of a
Darlington (no symbol, although it is alluded to), an SCR (part of “the
thyristor family” but with no explanation), a Triac, and an IGBT.
Chapter 3 continues into power and heat management issues with device
temperatures, heat sinking and the like. There is then a massive jump
into The Magical Mysterious Op-Amp which Ashby approaches with a
repeated reminder that the inputs to an op amp are high impedance. He
treats the device as a summing block with both a ve and a –ve input
plus a gain element. That’s fine. He also points out, quite correctly,
that the massive open-loop gain does not produce huge voltage swings –
because of the limitation of the voltage rail(s) – but doesn’t emphasize
how close to the rails the output can get, and why.
Negative feedback is introduced as well in this Chapter with the
usual op amp equations and he also briefly looks at positive feedback
while only mentioning oscillators. Ashby then spends time on binary
numbers and gets into logic gates and truth tables before considerable
pages on microprocessor basics, I/Os, and a bunch of oddball stuff
allegedly related to µPs: phototransistors, Hall devices, digital
encoders, potentiometers (and ratiometers, without using the word),
sensors, grounding, LEDs, multiplexing, and incandescent lamps. All are
basic – too basic – and digital pots are obvious by their absence.
After sixty-four pages, nearly one-quarter of the book, Chapter 3 comes to an end!
Chapter 4 is entitled The Real World which argues for the analog and
digital worlds, without once pointing out that digital is just a special
case of analog… The author uses a comparator model as an example of an
ADC and then a low-pass filter as an example of a PWM DAC. I dislike
this approach, which will only confuse the beginner. I would much prefer
to see a conventional amplitude/sampling analysis of the creation of a
digital counterpart and then a straightforward voltage resistive ladder,
the model of 90% of practical circuits, as the DAC.
The Chapter continues with a look at parts that are imperfect:
capacitors, resistors, semiconductors, and voltage sources (Ohm’s Law
would have been a good place for that one). There is then a Robust
Design section, which is management theoretical rather than engineering
practical, and Some of My Favorite Circuits, which are all rather
trivial. These are followed by a section of just six pages on power
supplies. There are a myriad of expressions here that grate but among
them are the use of “signal” to describe a dc voltage, “center tap
bridge rectifier” to describe a half-wave arrangement, and using a
filter capacitor to make the output less “bumpy” rather than describing
the filtering of the ac component. Linear regulators are treated as just
blocks but switching regulators are given a good description, albeit
without some nice current drawingsto follow along with. Ashby then
follows with about eighteen useful, but not terribly practical, pages on
dc and ac motors.
Chapter 5 is entitled Tools and spends about the same number of pages
on soldering as it does, in total, on test meters, oscilloscopes, logic
analyzers, and simulators. The Chapter then continues with People
Tools, which is actually a primer on the sales channels for components.
Chapter 6 is Troubleshooting, which consists of essays on component problems, EMI, and bugs in code. Generic but readable.
Touchy-Feely Stuff is the matter of Chapter 7 and consists of further
essays on management, employees, interviewing techniques, and the like.
Is it relevant to the text? Why not, I suppose. A very incomplete
glossary and an index round out the book.
Electrical Engineering 101 is not really about electrical
engineering at all. It is about electronics. Is it the best it could be?
Absolutely not; there are huge improvements that could be made that
would turn the book into a much more solid and useful text: Newnes
should have been on top of that editorially before it reached the Third
Edition.
I like the Thumb Rules scattered in each section, although some of
them are a little too folksy. Ashby also shows an overfondness for
understanding the charging characteristic of a capacitor, something he
raises multiple times. There is a screaming need in the book to get the
balance better and to delve into some real circuits. And, of course, the
idea that discrete transistors should be avoided at all costs when op
amps are available could drive any sane analog designer screaming mad!
There are many who would find this book to be a useful primer in many
ways; there are others who would find it very confusing. It deserves a
buying audience but I look forward to a Fourth Edition that is more
carefully structured and balanced for the putative designer.