Scope and size

‘Little’ is apt here because that companion, ABC of Capacitors by Stephan Menzel is small: just 76 pages as opposed to a whopping 308 for the Trilogy. But like the Trilogy of Inductors it’s a hard bound book, it’s cheap (€9.90 from the Elektor Store), and has the same crisp layout and high paper quality.
Of course, Würth are big-gun suppliers of “almost-anything-capacitor” but to say that ABC of Capacitors is published to sing their own praises (i.e. sell-sell-sell) is missing the point – there isn’t a single Würth order number in the book. Instead of commercializing, Würth operate at the root: the knowledge level. In the tradition of Trilogy of Inductors, the new book ABC of Capacitors is a solid discussion of electrical, electronics- and physics related aspects of the component sec, in this case the capacitor. Audiophools will not find anything in the booklet to underpin with conviction the results of their “Sunday afternoon sound session with ultra-linear cap XYZ at just $45 each”. Rather, in the book they will read about non-subjective things like a capacitor’s tangens-delta factor, and hopefully draw their conclusions. All the while of course enjoying the music at very low distortion.

Order must be

As suggested by its subtitle the book follows this order in presenting the information:
  1. Basic Principles
  2. Capacitor Characteristics
  3. Capacitor Types
Which I find hard to argue with given the exhaustive and sound treatment in chapters 1 and 2 in any case. The coverage of Principles and Characteristics is textbook/summary style with — remarkably these days! — impeccably typeset equations and zero compromising with any of the dreaded Greek characters like alpha, delta, theta, and pi and phi, lower case or capital! We also get proper subscripts and even the minus sign has the same width as the plus sign. I am quick to add that I am cutting corners myself here by not showing any of these symbols here properly but that’s because Elektor’s web-based publication system for reviews and news items is sure to mangle everything beyond plain text.

The weak point of the booklet is not found in errors, omissions or long winded formulations — quite the opposite — but in the absence of a closing chapter on capacitor selection in practice. There is a hint of this minor shortcoming in chapter 3 already, which duly discusses these capacitor types with a fixed capacitance: film, electrolytic and ceramic, the latter divided in Class-1 through -4.  Sadly the types are not linked to any typical applications in the industry, which would have made a smooth transition to a selection guide to close off the book. For example, although the NP0 capacitor is mentioned as belonging to the Class 1 ceramics with a temperature coefficient TC=0 (in theory), a short discussion of its use in oscillators would have helped to give the book a more practical look and feel. I do respect the clear perimeter though set out in this regard by the author: theory goes before practice.