H. P. Friedrichs (AC7ZL) Homepage

Tucson, Arizona U.S.A





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Marvelous Magnetic Machines is Now FOR SALE!

It took a great deal of work and the help of a lot of great people, but my latest book, Marvelous Magnetic Machines , is now available for purchase! For the latest details, click here!


H.P. Friedrichs Returns to Broadcast Radio!

Among the great programming on KVOI AM 1030 is a radio show entitled  America's Fabric. The purpose of the program is to, "...communicate a positive understanding of America’s heritage and to make clear why individuals from so many nations around the world have for centuries sought to live in the United States." I was honored to be asked to write and present a segment for that show. I chose to discuss some of the background behind the development of television, and in particular, the contributions of Philo T. Farnsworth. My episode, #647, can be listened to here!


What? Electronic Components Made From....Dirt?

Who would have thought that the black particles found in the sand of Arizona roads and washes would find application in a radio tuner, oscillator, antenna, or transformer? Well... I did... I tried it... and it works! In fact, you may be surprised as to how far I actually went with this idea. Read about my experiments here. Read about my experiments here!


K9 QRP Article Appears in CQ Magazine!

Some time ago, I coined the phrase "K9 QRP." What's that? It's the ideal way to enjoy a four-footed friend, the outdoors, and low-power radio communications all at once! Last year I penned an article about this idea called K9 QRP: Fun with Ruff Radio. I'm pleased to report that CQ Magazine has published that manuscript and it appears in their June 2017 "Take It To the Field" issue. Until your copy shows up in the mail, why not visit my web page for some additional information here!


A Homemade Morse Key... Made From.... WHAT?

Amateur radio operators have a long and rich tradition of building their own tools and equipment from scrapped, salvaged, and repurposed junk. Morse keys are no exception. For years, hams have fashioned creative and functional sending instruments from a staggering variety of household odds and ends. Here is a novel design for an exceptionally nice straight key which is fashioned from a disemboweled computer hard drive. Read about it here! Then build one of your own!


Who Really Invented the LED?

LEDs (Light Emitting Diodes) are everywhere! They've become essential components of everything from cars to computers, televisions to telephone networks, audio gear to medical equipment and more. If trends continue, they will eventually dominate all of domestic and industrial lighting. But where did they come from? You are likely to be surprised when you discover the origin of the LED, but even more so when I demonstrate how you can create a primitive LED with nothing more than a flake of industrial abrasive, a power supply, and a sewing needle!

Read the article here!  Watch an interesting video demonstration here!


AC7ZL Appears on QSO Today!

Early in May I was surprised to receive an email from Eric, 4Z1UG, host and creator of the famed QSO Today Podcast. QSO Today is noted for the exceptional quality of its guests—a veritable Pantheon of ham radio's most recognized names. This list includes the likes of Ashhar Farhan (VU2ESE), Bill Meara (N2CQR), Phil Anderson (W0XI), Bob Heil (K9EID), Tad Cook (K7RA), Budd Drummond (W3FF) and even the world famous Art Bell (W6OBB). I was honored with an invitation to be interviewed and gratefully accepted the opportunity for this very small fish to swim among some of the greatest.

My episode was released May 28. Look for Episode 95 here.

If you are visiting my site for the first time and are interested in my technical books, feel free to look around. A list of sellers and distributors of my technical books can be found here.

Looking for something different in fiction? Take a look at Riley's Way and Numbers, Neighbors, and Nobody's Business


Announcing New Books By H.P. Friedrichs!

As an author, I am best known for my technical writing. Examples of this are The Voice of the Crystal and Instruments of Amplification.  Articles I've written have appeared in the Xtal Set Society newsletter, QST Magazine Online, Practical Wireless and elsewhere.

However, I sometimes amuse myself by writing fiction. I've recently published a work entitled, Riley's Way. It's an adventure story of sorts, as seen through the eyes of a smarter-than-average German Shepherd dog. Available through Amazon.com, I invite you take a look here.

Are ghost stories more your cup of tea? Then why not have a look short collection I've created entitled, Numbers, Neighbors, and Nobody's Business. Also available through Amazon.com, I invite you to take a look here.


New Section to My Web Site!  HPFParts!

Anyone who is serious about experimenting with electronics, computers, or radio has a junk box—or two, or three, or ten... or a room, shed, or garage...You know who I'm talking about.

Unfortunately, if you're like me, you've noticed that reality ends up placing constraints on all the projects we intend to do "someday." In reality, time is limited, and so is storage space. Rather than let these treasures accumulate, it is sometimes best to choose where we shall focus our efforts and divest ourselves of those items that won't advance our immediate objectives.

HPFParts is a new section of my web site where I will occasionally list parts, materials, or equipment that I no longer want or need, but might be of use to persons with similar interests. Please, have a look and check back from time to time!


All about Crystals for Crystal Radios!

Every crystal radio set builder knows that you can detect radio signals with a tiny glass germanium diode. If you want to go old-school, you use a chunk of galena and a wire cat's whisker. But are those your only options? You might be surprised to learn that old-timers knew of many dozens (perhaps hundreds) of useful minerals, metals, and compounds that can be combined to fabricate primitive semiconductor diodes. Read about it here.


Having Problems With Telemarketers And Their Robodialers?

Telemarketers—you know, the people who selfishly hijack equipment and services you paid for to interrupt your sleep, dinner, or privacy in hopes of selling you something?  They are a species onto themselves. I call them Telephonium Parasitus. A T. Parasitus infection is essentially an electronic malady. In some cases, it can be cured through electronic countermeasures. Read about it here.


MORE Neat People And Their Nifty Projects!

As the result of publishing my own work, I have had the pleasure to meet (or at least learn of) a large number of experimenters with interests similar to mine. All of this work is impressive, and some of it is downright astonishing. Take a look at  the latest additions to my Guest Gallery project page, including Dr. Stanley Kaplan's version of my CDROM Radio and Stephanie Simek's crystal radio art exhibit.


I Have A New Distributor For My Books!

If you are a student (or master) of  hands-on, from-scratch, craftsman-oriented activities like knife-making, blacksmithing, gunsmithing, metalworking, carving, or pottery,  then you don't need an introduction to Artisan Ideas dot Com. Artisan has provided the craftsman community rare and interesting books and DVDs on these subjects for more than a decade. I am very pleased to announce that Artisan is the latest among an outstanding group of sellers/distributor for my books. Please give them a visit!.


Not All Of My Projects Are Electronic In Nature!

An electric guitar that I keep on a stand in my office has long been an object of interest to my grandson Kaden. When he asked if he could have it, I thought him just a bit too young, and declined to give it to him... for now. Read here how I built him his own guitar from bits and pieces that many people would have regarded as trash.

Over the past fifty years Barbie, the most popular and ubiquitous doll ever made, has driven or piloted every conceivable vehicle from cars to boats to jet planes. At one point, you could even purchase Barbie with a space suit. The birthday of one of my grand daughters, Kella,  provided the incentive  to construct a one-of-a-kind Barbie accessory that any little girl (and a fair number of little boys) would love to play with. Read about it here!


Build A Mechanical Magic Eye Tube!

If you're less than 50 years of age, and you don't tinker with vintage radios or antique test equipment, you're probably unfamiliar with the magic-eye tube. Pity, because you've missed out on seeing one of the neatest display devices ever produced. Click here to see an approach to building a fairly convincing electromechanical equivalent, using simple junk parts.


Neat People And Their Nifty Projects!

As the result of publishing my own work, I have had the pleasure to meet (or at least learn of) a large number of experimenters with interests similar to mine. All of this work is impressive, and some of it is downright astonishing. Take a look at my new Guest Gallery project page right here.


My First Appearance on Broadcast Radio!

I rarely use the microphone on my ham radio equipment. Sure, on a blue moon, I may be heard on one of the regional 2-meter networks, and I do have a couple of SSB contacts in my HF log book. However, most of the time, if I'm transmitting, I'm either working CW (morse code) or PSK-31.

 That's why it was both exciting (and a little bit spooky) to be asked to visit the studios of KVOI AM 1030, to appear on Charles Heller's program,  "Liberty Watch/America Armed and Free." On the program, we briefly discussed my books, and I spent some time discussing, in mechanical terms, how broadcast radio works. I've never had an hour of my life flash by so quickly.

Interested in hearing what you missed? For the next few weeks, a recording of that program should be available here.



It Isn't About Politics!

The members of our military have volunteered to put their lives into jeopardy, and the lives of their loved ones on hold, simply because their country asks them to. If this kind of sacrifice is not worthy of gratitude and appreciation, then nothing is.

Some people are upset about American foreign policy...fair enough, there's plenty of room for different opinions. But the next time you see a man or woman in uniform, don't forget to tell them "thanks."

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  (Last website revision 04/02/2023