H. P. Friedrichs (AC7ZL) Homepage
The Voice Of The Crystal
Learn what others think of The Voice of the Crystal!
A Review By Make Magazine
If television character "Macgyver" subscribed to one periodical, it would be Make Magazine. Issue after issue is filled with machinery, vehicles, electronics, and bizarre and amazing expressions of technology and art designed and built by everyday people from common materials. It's a magazine whose central philosophy is dear to my own heart, which is why I was flattered to find the following review in Issue #21. It is reproduced here with permission.
The Voice of the Crystal and Instruments of Amplification by H. Peter Friedrichs
Review by Gareth Branwyn
The Voice of the Crystal has a stellar reputation amongst radio geeks, and for good reason. This guide to building radios is filled with great ideas and utterly awesome projects. I love the author's assertion that every curbside can of garbage contains all the parts to build at least one radio. Peter Friedrichs builds headphones from soup cans, shoe polish tins, and disposable lighters, along with paper tube condensers (old-school capacitors), detectors (old-school diodes), radio coils and more. If you have a maker bone in your body, you can't look through this without itching to grab your tools and dive into the nearest dumpster.
In his follow-up book, Instruments of Amplification, Friedrichs shows you how to build vacuum tubes, transistors, transformers, and other homebrewed amplifying devices. The 297-page book is also crammed with lots of basic electronics background, history, theory, and build tips. I can't recommend these books highly enough.
A Flattering Review From Amazon.com
An Historical Treasure, December 25, 2001 Reviewer: A reader from Hampton, NJ USA
An amazing book! A real gem to own for anyone interested in understanding or building a radio from scraps. This simple little book is filled with illustrations and text that is worth more than 100 radio books put together. I bow to the author.
A Review by Practical Wireless Magazine
Practical Wireless is a delightful amateur radio magazine, published in the U.K., with a long a distinguished history. The following review, written by editor Rob Mannion, appeared in the September, 2001 issue. It is reproduced here with permission.
New Titles To Add To Your Bookshelf - The Voice of the Crystal
Rob G3XFD PW's Editor often has books arriving on his desk for possible review, many are very specialised titles and often self-published by the authors. Here he looks at a book which should really appeal to readers who like to build crystal sets from scratch!
It's appropriate that American author Peter Friedrichs has decided to write, illustrate and publish this book himself - subtitled "How to build working radio receiver components from scratch" - as the contents concentrate entirely on building simple crystal radio receivers - literally from the ground up! By this I mean that Peter describes just how you make literally everything yourself - including headphones!
Peter's finished engineering work must be very good ...much better than the general photograph quality, although overall it's a well designed and laid out publication. However, it's a pity that the photographic reproduction does not show the shiny varnish on his superbly completed projects as this original photograph does. But at least anyone who buys a copy of this book will have a good idea of what they can build with his advice. If you're used to the approach in the G QRP Club's journal Sprat - you'll enjoy Peter's book too.
Coil construction, along with general wiring on a crystal set is easy enough...but how about making your own fixed and variable capacitors? There's also a fascinating array of designs for headphones - ranging from one called the Gallows to another type using the piezo-electric crystal from an old cigarette lighter. Fascinating stuff indeed! Highly recommended for the keen constructor - especially those wanting an interesting challenge!
A Review by QST
Last year, I was honored to have had The Voice Of The Crystal reviewed within the pages of QST Magazine. The body of that review (May, 2000) is reproduced here, with their permission:
The Voice Of The Crystal, Reviewed by Steve Ford, WB8IMY, QST Managing Editor
The introduction to The Voice of the Crystal ends on page 5 with an understatement: "You have never read a book like this before."
The author, H. Peter Friedrichs, can make such a declaration with confidence because it is highly unlikely that you'll encounter another book like this. There are plenty of books about crystal radio receivers (or roots radio, as I call the genre), but this latest offering from The Xtal Set Society takes the concept of elementary radio to an entirely new level. The Voice of the Crystal is essentially a guidebook to the art of building radio receivers from scratch. "Scratch" doesn't mean components purchased at Radio Shack, or lifted from abandoned gear. This is "scratch" in its most elemental sense -- discarded glass, scrap metal, you name it.
The first four chapters give a short introduction followed by a summary of the theory behind crystal-detector receivers. With chapter five The Voice of the Crystal launches into a discussion of headphone building that spans the next four chapters. Friedrichs shows you how to create working headphones from such flotsam as shoe polish tins and soup cans using unusual components such as transformer laminations and plastic cigarette lighters.
Chapter nine introduces you to the detector and chapters 10 and 11 offer some astonishing detector construction ideas. Sure, you could use a simple diode or find at bit of galena somewhere, but that would be too sophisticated for The Voice of the Crystal. Instead, the author discusses making detectors out of safety pins and razor blades, among other things. One of my favorites is a detector created by suspending two electrodes in a gas flame!
Capacitors are more straightforward (metal foils, plates and insulators). You can make variable capacitors any number of ways. The most unusual design described in the book, however, involves a 2-liter plastic soda bottle filled with salt water and equipped with two external plates. You place the bottle in a wood cradle and turn it slowly to vary the amount of water between one plate and another.
The Voice of the Crystal ends with brief discussions of coil and antenna designs. As Friedrichs is quick to point out, a good ground and a long antenna are crucial to the success of any crystal radio.
This book would make an excellent addition to any science classroom. Imagine how impressive it would be for students to listen to signals received with radios made from "trash." The Voice of the Crystal is well written with a style that educates without sedation. The hand drawings could benefit from the talents of a professional graphic artist, but that would probably violate the back-to-basics spirit of the book.
The Voice of the Crystal is worthwhile for anyone who still harbors a spark of curiosity. Following Friedrichs' instructions you can put together a radio that will take you back to the days of Fessenden, Marconi, Tesla and the other pioneers. Best of all, you'll rediscover the thrill of grabbing signals out of the air with your bare hands
A Review by The Citizen Scientist
By Sheldon Greaves of SAS
When I was about eleven, I found an old book from the 30's or 40's at a local library book sale that contained science projects for young boys. One of these was a crystal radio. Excited as only a kid can be, I set out to build it. I gathered the required parts, including a brand-new spool of 28-gauge wire, and cobbled the thing together. It didn't work. I tried to figure out why, but knowing next to nothing about what I was trying to do, I grew discouraged and gave up. Now, many years later, I have some insights into why my crystal radio failed to function, and I owe most of those insights to reading Pete Friedrichs' book.
The crystal radio is part of the American technological mythos. It has become a metaphor for homebrew, do-it-yourself ingenuity and with good reason. While it may seem crude when compared with today's sophisticated consumer electronics, in the earlier decades of the previous century crystal radios represented a remarkably advanced technology lovingly hand-crafted in thousands of basements, attics, and garages. Moreover, these projects often constituted the early steps taken by countless budding scientists and engineers who went on to design today's high-tech wonders.
Crystal radio technology seems to be undergoing a renaissance among hobbyists and tinkerers. Much of the impetus can be ascribed to a flurry of new publications on the subject, and one of the most remarkable is "The Voice of the Crystal." The subtitle, "How to Build Working Radio Receiver Components Entirely from Scratch," is no hyperbole. When author Peter Friedrichs says "from scratch", he means it. I read with growing fascination about how he turns wire, wood, bits of tubing, metal cans, nuts and bolts and various other items scavenged from God-knows-where into working radio components. Not once is one required to visit the local Radio Shack or other electronics supply store in order to buy anything more elaborate than wire or an alligator clip.
Now, I confess when I first saw the book and read the subtitle, I surmised that this book might be too much of a "niche item," something only for subspecialists of a dying art. But this book is broadly educational in a way I never expected.
Earlier I referred to mythology. There is a perception among the non-technical public, no doubt encouraged by popular media and science fiction, that there exists a breed of technical wizards who can transform commonly available materials into a working phaser cannon or turn a deck chair into a hovercraft. The underlying basis of this belief, it seems to me, is the perception that these super-tinkerers know deep, super-obscure facts of physics and chemistry. What Friedrich demonstrates through this book, however, is that understanding the basics of science, not the obscurities, is what make his technical marvels a reality. The basics taught here apply across many areas of physics and electronics, and the problem-solving approach implicit in this book will serve the reader well, no matter what their ultimate field.
This brings me to the text of the book itself. Friedrichs' prose is exemplary in its clarity and precision, literary attributes for which engineers as a group are not noted. He understands how to take you through a concept, such as resonance or impedance, so that you understand it. Moreover, you understand how it informs what you are trying to build. This is the great advantage of taking the "from scratch" approach. At the end of the day you know why things work, and not just that tab A goes into slot B.
Now, on to specifics. After a brief but useful discussion of basic theory, Friedrich goes on to discuss different kinds of headphone components. One uses a shoe polish can and a doctor's stethoscope among other items. Though not the most elaborate, my personal favorite is the headphone driven by the piezo crystal scavanged from a cigarette lighter. The sheer simplicity and elegance of this project alone is worth the price of the book.
From there, he goes on to detectors, explaining the theory behind them and the design considerations germane to building them. Most of the detectors employ a crystal or something similar. Next come condensers, including a fiendishly clever design for a variable condenser using overlapping leaves of roofing metal. Coils are treated next, which turns out to be a more elaborate discussion than I was expecting. The crank coil project is worth a good, long look. Still, like the rest of the book it remains clear and infects you with the author's enthusiasm for his subject. Sections on simple tuners, antennas, and assorted circuits and formulae round out this book.
One other thing you will note is the artistry that goes into the components described here. I've included some color photos of some of these; the black-and-white photos in the book don't really do them justice. Some of these components are remarkably pleasing aesthetically and would not look out of place in an art gallery. If nothing else, they display a degree of care and craftsmanship that reflects the best traditions of the home experimenter.
Whether or not you plan to build your own crystal set, this book is a delightful read. Frankly, I couldn't put it down. I can't think of a better way for a fledgling scientist--young or not so young--to make a beginning at learning the secrets of nature.
(revised - 01/25/2010)