Dear Dennis...
EN-Genius Network's Dennis Feucht answers your design
queries in his new Circuit Design Clinic!
April, 2008
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EN-Genius Network presents a new, interactive
analog design service to readers! Send us your design questions (with
relevant data; schematics in JPEG or GIF, please) for some free
engineering advice from EN-Genius Network's circuit
consultant, Dennis Feucht, on how you might solve a design problem or
improve circuit performance. Submissions may be edited for clarity or
brevity, and submitters and their email addresses will remain anonymous
(unless otherwise indicated). Please send your questions to Dennis here.
An Analog Electronics Companion: Basic Circuit Design for Engineers and Scientists
by Paul McGoldrick
by Scott Hamilton, Published by Cambridge University Press
ISBN 13: 978-0-521-68780-5, paperback, 648 pp plus CD, $70.00, Reprinted June 2007
A review notice on the back of the reprinted book (with corrections from the 2003 First Edition, which I never saw) says:
“A rare fusion of rigorous theoretics [sic.] and bench based experience written in an accessible, entertaining style. An Analog Electronics Companion is rewarding to read, and an enduringly valuable reference for analog practitioners.”
There were other reviews on that same back cover, all glowing in some way, with one even suggesting the text as a worthy successor to Horowitz and Hill’s The Art of Electronics.
I don’t think so.
And that quotation above comes from someone for whom I have the greatest respect and admiration in the analog world: Jim Williams from Linear.
The author is a retired Senior Lecturer in The Department of Physics and Astronomy at the University of Manchester in the UK. And it shows. If the CD had not included an evaluation copy of SPICE (from MicroSim, which was bought by Orcad, both of which were then acquired by Cadence) it might well have been put down and forgotten. But the fact that this is a book that encourages simulation means that it has to be salvageable, certainly compared to a couple of extremely dubious texts emanating from academia in the last couple of years with that word "analog" in their titles.
The book is well written and the author was involved in teaching electronics as a crossover subject, but let’s debunk the dreck in the title of the book: Basic Circuit Design is not what this book is about. It is more a collection of essays, without a really common thread: not a logical teaching course, and unnecessarily mathematical for the design engineer’s hands-on job.
The first 92 pages cover mathematics: trigonometry, geometry, series expansions, logarithms, exponentials, vectors complex numbers, differentiation, integration, equations and determinants, Fourier transforms, Laplace transforms, differential equations, and convolution. The author, in his Preface to the book says, “It will be evident from the book’s contents that I do not subscribe to approaches that avoid the use of mathematics at almost any cost. Mathematics is the language of science and you place yourself at a considerable disadvantage if you cannot speak it competently. It provides the path to deeper understanding of how systems behave and, in particular, it allows you to make predictions. Design is in essence prediction since you are expecting the system to meet the requirements.”
Mathematics is the language of science is the phrase I would pick a fight with in translating it to an engineering environment. I have always enjoyed mathematics; I did well in state exams; I did even better at college. And it wasn’t because I was taught well: my math teacher at secondary school was an idiot from County Cork who talked through the side of his mouth with his hand under his chin and his elbow resting on a radiator. No, I had to teach myself...and, later, when I was also a Senior Lecturer, like the author, I had to teach mathematics throughout undergraduates’ first year – because they had been so badly taught at school – just to bring them up to a level of understanding of what they were doing, and facing.
But you can go too far with this, and this book does just that, in my opinion. In addition, he does things like using differentiation in a Chapter before he remotely begins to cover the subject.
Part 2 of the book is devoted to Physics and, in his introduction to the Chapters, the author says that, “This part is a brief introduction to some of the topics that seem relevant and which to some extent are missed out in the training of electronic engineers.” The topics included are current flow, energies, Kirchoff’s laws, Faraday’s law and Lenz’s [sic.] law (which is neither stated nor explained), currents and fields, magnetism and relativity, Maxwell’s equations (in just 4 pages), conductivity and the skin effect, quantization, dielectrics and permittivity, magnetic materials, units of electromagnetism, and noise.
Certainly I was taught, and did teach, these topics at college in electrical and electronics engineering courses. But the difference was intensity. The two most important topics in this Part of the book are Kirchoff and noise. The former is covered in just 3 pages and the latter (covered in 5) only looks at uncorrelated noise.
The meager coverage of Kirchoff is balanced out in Part 3 of the book (Introduction to Circuit Mathematics) with 7 pages devoted to Ohm, Thévenin, Norton, and superposition with two simulated complex examples of variable loads. These are ongoing topics at college level electronics engineering.
Part 3 continues with A.C. [sic.] theory (a whole 6 pages of it), phasors, phase and amplitude, resonance, bandwidth and risetime (done the old-fashioned academic way, not the realistic manner in which Michael Steffes is covering it here on EN-Genius in our technoteZONE), pulse and transient response (academic, again), equivalent circuits, Bode weighting, feedback, noise in circuits, hysteresis, bridges, approximations, control systems, filters, and transmission lines.
Part 4 of the book goes into circuit elements, including resistors (no pots), capacitors, inductors, transformers, diodes, bipolar transistors, field effect transistors, temperature dependent resistors (i.e., thermistors), coaxial cables, and crystals.
On to Part 5, where SPICE circuit applications are addressed with absolute value circuits and a current output example (probably by Dennis Feucht?), oscilloscope probes (outdated), operational amplifiers (including non-inverting, sum and difference amplifiers, integrator, and composite – all dealt with in a standard, theoretical, academic manner), rectifier circuits (including voltage multipliers!), integrators, differentiators, two-phase oscillators (quadrature generation), Wien-bridge oscillator (8 pages!), current sources and mirrors, power supplies (only dc input with some weird regulator examples), current-feedback amplifiers, fast operational picoammeter (I kid not – for 16 pages!), three-pole single amplifier filter, open-loop response, lumped or distributed (a short discussion on how short transmission lines can be treated), immitance (gyrators: why?), Maser [sic.] gain simulation, frequency-independent phase shifter, ratemeter (frequency-to-voltage conversion), baluns and high frequency transformers, directional coupler (without a single physical drawing to help understand how the beast is put together), power control or hotswitch (as in ramping and sequencing), modulation control of a resonant circuit, photomultiplier gating circuit, transatlantic telegraph cable (really!), chaos, and Spice [sic.] notes.
The whole of this Part 5 is like a project book. Things that have been delved into over the years with no logical sequence between them. It reminds me of some of my practices when teaching and has, in fact, inspired my Editorial for the week.
This is not a bad book, per se. The use of simulation throughout is admirable. But it doesn’t hit the target. This is not the first stop for a new analog designer; it does not replace Horowitz & Hill. I cannot properly identify the audience that it would attract. Maybe the undergraduates that passed through Scott Hamilton’s lecture theaters over the years? The approach is academic and impractical. But, it is a fun read, well written and well presented. The errors were, that I saw, few and far between, though the use of capital S for seconds really does grind. I don’t know what a microsiemen (µS) is, but thankfully we have no use for them on the analog engineering side of the aisle anyway.
It is nice to see references to many of the works of people I know in the industry and I was particularly pleased to see that the author has kept copies of old issues of Wireless World where a well-known engineer wrote under the nom-de-plume of Cathode Ray. I was introduced to the real man when I was a teenager and learned all I know, and love, about phasors from him. He has to have passed on by now, but the only clue I will give to his identity is that he was the father-in-law of Buster Crabbe. And I’ll let you look up that 50-year old story…
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