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Instruments of Amplification


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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.

Crystal Clear:

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 Review By Brian Hope, Bisbee Wireless Apparatus Co.

Yes, you too, can build your own thermionic valve. (Never throw away wire again). From H.P. Friedrichs, the master of home-brewing, comes his latest work, Instruments of Amplification. In some respects, IOA is a companion book to his previous work, Voice of the Crystal. In VOTC, the author leads us through hard-core home brewing of basic radio systems. In IOA, we are taken to the next level and may expand upon these systems through amplification devices.

On one level, Instruments of Amplification is a highly detailed, step-by-step guide to building amplification devices entirely from scratch; and from commonly available materials. Just enough theory is presented to help illuminate basic precepts; the work is heavily illustrated with photos, line drawings, engravings, and charts. IOA is also heavily annotated with online, print, and CD-ROM references. Of particular interest are the author's photographs of his museum grade devices.

This is not just another project book, however. The work is an exercise in creative, divergent thinking. In this age of modular, throwaway components, Mr. Friedrichs presents a highly refreshing approach to top-down problem solving. Although this book deals with electronic components, one may construct algorithms for virtually any process by adapting Mr. Friedrichs' methods. I'll bet you didn't know that the wagon wheel and the vacuum tube have a lot in common, Mr. Friedrichs will explain. The astute reader may garner several skills, both in mechanical and mental realms.

Instruments of Amplification is superbly written. For the technical-minded, it's a gem. For the non-technical it's a good read. Even if you do not attempt building any of his devices, you will never again look at problem-solving in your accustomed manner after reading this.

The author admonishes, "You have never read a book like this..." He's right.


A Review By QST Magazine American Radio Relay League

QST Book Review, January 2004

Instruments of Amplification by H. Peter Friedrichs, AC7ZL, Reviewed by Steve Ford, WB8IMY, QST Editor

The title seems dry and even imposing, but the book is another matter entirely. Instruments of Amplification is a delightful foray into "extreme radio," as the author, H. Peter Friedrichs, AC7ZL, calls it.

If the author's name is familiar, perhaps you recall The Voice of the Crystal, the previous book by Friedrichs that explored every conceivable homespun method of detecting a radio signal. It was reviewed in the May 2000 QST.

Instruments of Amplification takes The Voice of the Crystal to the next logical step--amplification using homebrew components. Friedrichs guides the reader on an amazing journey from electromechanical amplification to vacuum tubes and finally solid-state devices. Along the way he explains the basics of amplification in a conversational, easy-to-understand style. Take a look at this passage from a discussion of how atoms in gas molecules can interfere with free electronics during thermionic emission...

"To visualize this type of interference, picture yourself trying to run a straight path through the plaza of a crowded shopping mall. You may advance a short distance, but the odds are that, somewhere along your course, you'll eventually collide with another patron. If the other shopper is large enough, he may well send you back from whence you came!"

When I was first learning electronics in high school, no one bothered to illustrate the importance of a vacuum-tube vacuum this way. I would have grasped it in an instant if I had a copy of Instruments of Amplification at hand.

Not only are the explanations of basic amplifiers enlightening, the projects used to illustrate the explanations are astonishing, at least to 21st century sensibilities. Friedrichs doesn't just talk about mechanical, vacuum tube and solid-state amplifiers, he builds them out of component parts. Friedrichs shows you how he has built mechanical microphonic amplifiers from balancing scales, and even homebrew vacuum tubes from discarded hamster water bottles, canning jars, and votive candle jars, among other things. He also details hand-made semiconductors. Yes, all these projects really work!

Instruments of Amplification isn't a slick commercial book with professional illustrations, but the writing is top-notch. Even if you don't end up assembling your own tubes and transistors, just reading about the author's efforts is educational and entertaining. I'll be waiting for the next progression up the extreme-radio ladder: an amateur transceiver built entirely from homebrewed tubes or transistors!


A Review by The Citizen Scientist

By Sheldon Greaves of SAS

Recently it was my pleasure to review Pete Friedrichs' remarkable self-published volume The Voice of the Crystal (hereafter VotC), which describes how to make working radio receiver components entirely from scratch. That book is part of a recent revival of crystal radio technology among radio and science enthusiasts. VotC covers the construction of radios with the same spirit, if not the same methods, used by early radio experimenters.

In my view if VotC represents a revival, Friedrich's latest book, Instruments of Amplification, represents a minor revolution. Many amateur scientists labor under the assumption that there are certain things that are simply beyond the capability of the home experimenter. In many cases, this is both true and prudent; one can spend inordinate amounts of money or even endanger ones' health by trying to reproduce technologies that are cheaply available off the shelf or simply ought not to be trifled with.

I had always assumed that vacuum tubes and transistors were among those things that were outside the bounds of the amateur scientist. This brings us to the book's subtitle: Fun With Homemade Tubes, Transistors, and More .

Instruments of Amplification picks up where VotC left off. Although Instruments is a wonderful read even if you haven't read VotC, the two books really belong together. Friedrichs shows you how to build devices that can amplify the signals pulled in by a crystal set, while at the same time giving a remarkably lucid treatise on what amplification is and how it works. The book begins with an excellent explanation of the nature of amplification; what it is and what it is not. The early projects are fairly simple devices, such as a telephonic relay built from parts taken from an old telephone handset. Another is the "balance beam amplifier" which, although simple conceptually, seems challenging to build.

But then, after an excellent section on impedance, we move into vacuum tube technology; glow tubes, diodes, audions and triodes. These chapters include a very solid introduction to vacuum pumps and vacuum technology for the home experimenter. It's a bit of a side trip, but a very interesting and useful one. I confess that the part of the book describing tubes was my favorite, if only for the sheer chutzpah of someone successfully building something that is both "obsolete" and supposedly beyond the home experimenter. And as if that weren't enough, Friedrichs finishes the book with a section on home semiconductors, homebrew transistors, and some good information on power supplies.

One might ask, "Why bother?" If you read my previous review of VotC, you should already know the answer, but let me briefly reiterate. Building scientific equipment from the ground up requires a more rigorous intellectual effort that ultimately yields richer rewards. It is by starting from first principles that we best learn how and why things work.

Throughout this book the authors explains concepts and projects with the same outstanding level of clarity that we have come to expect from his earlier book. Another aspect of his work that I very much enjoy is the way he leaves his projects open; most of his chapters close with ideas about how one might expand on what he has done and go further. Indeed, if you visit the online photo gallery associated with this book, you'll find pictures of many projects that are not mentioned in Instruments.

Earlier I said that this book was revolutionary. I make that claim because Friedrichs has given us a glimpse of how far we can push existing technology and find ourselves doing and building things that were thought to be beyond the scope of amateur scientists. Making a vacuum triode out of an ashtray and a votive candle holder qualifies, I think, as pushing the envelope. This is truly an inspiring, instructive, delightful book. 



I Get Email!

Almost as soon as Instruments Of Amplification was released, I began receiving e-mails about it. These are excerpts of what some of my readers have to say:

I looked at the updates on your web site concerning the book. MAN OH MAN, I had no idea you had so much great stuff going into the Instruments Of Amplification book. It looks like it will probably be one of the greatest book for home experimenters ever written. It appears to be one of those great rare esoteric books that we always dream about finding someday. I can't wait to read it. I assure you it will be well read here. I hope all is well with you and that distributing of the book is going well- NS


Love your work. Heard about your new book on the crystal set yahoo group. I tinker, too, not nearly to the detail you do, but I'll bet we share a deep appreciation for the hardware store! - TP


I received Instruments of Amplification in the mail yesterday. I managed to get through the first couple of chapters last night. It is a wonderful book and you are to be congratulated for keeping alive the spirit of curiosity and experimentation. I think I mentioned to you before that I encountered the Alfred P. Morgan books as a child, and spent many hours building projects directly from the books, or projects inspired by the book. Your style is similar to Morgan's, in that you first instill a curiosity about the subject, then go on to investigate it in a practical and straightforward manner. I hope you will be as surprised by the reception of this book as you were by the reception of Voice of the Crystal. Thank you again for sending the book, I will cherish it more than my copy of Radiotron Designers Handbook. - DM


Let me congratulate you on your wonderful new book, Instruments of Amplification. I got it yesterday and simply could not put it down. I thought I knew a lot about the general topic of amplifiers, but you really took me to school. Great first-principle projects, clear explanations. Your section explaining semi-conductors, for instance, is as clearly presented as anything I've ever read on the topic and much clearer than most college texts. This is simply one of the best, if not the best, book of its kind that I have ever seen. I wish you tremendous success with this title.- SC


Just a note to thank you for a most enjoyable and thought-provoking book. This is the most entertaining reading I've had for nigh a while. If only time permitted, I would sincerely like to try some of the projects suggested. Perhaps in my dotage.- JW


Wow! What a great book. My wife has ordered both The Voice of the Crystal, and Instruments of Amplification, as my Christmas presents from Lindsays books. The hard part is having to wait till Christmas before reading them. Where did you get the idea for making your own tubes? I've searched the web after seeing your book in the Lindsays catalog, and with only one exception I wasn't able to find anything else on this subject. The concept just blows my mind. Is there any other resources on this subject that you could share? Forty years ago my father sat me down and we built a crystal radio together. Today I'm a EE and I think most of the credit goes back to that little crystal set. Those beautiful pictures of your audion tubes just cry out to be integrated into a multistage radio receiver. I have 2 little girls and I think I'm going to have to pass the tradition on to them by building one or more of projects. Thanks for the books and the old memories!- WW


Recently I purchased your two books, Instruments of .... and The Voice of... via Lindsays books.  All I can say is that I am quite impressed! I was impressed at your list of references.  I thought I was the only one with a copy of the "Crystals, Electrons, Transistors" reference.  Likewise the experiments with the crystal color center defects in KBr are surely worth learning more about.-BTA


Well I finished your books VOTC and IOA well before I intended to.  I  really didn't have time to read them, but I started reading the introduction of IOA when it arrived and couldn't put it down until VOTC arrived the next day.  I put IOA aside long enough to read VOTC then finished IOA.  Now I have to "catch up" on the things I should have been doing instead of reading the books! Overall the books are great!  Very well written and informative - I learned a lot.  I look forward to your next book and I hope it's about  practical receivers and transmitters that can be built from all the homemade components. I'm an Extra Class Ham and have been joking that one of the requirements of being a licensed Ham is that you have to be able to make a radio from junk anywhere and at anytime.  I'm learning that it's no joke - it can be done!  After reading your books, I can't walk through a hardware store, craft store, or past a pile of junk without looking at EVERYTHING and thinking about how I might use it to build some radio part or another.  It's great.- SVB


First I wanted to say thank you for the wonderful Instruments of Amplification. For years I've been pondering the idea of making my own vacuum tubes and your book was enough to convince me to move past "pure research" and start experimenting.-TC


(revised - 05/12/20210)