H. P. Friedrichs (AC7ZL) Homepage








My Projects

I am an inventor by nature. I love engineering and virtually any kind of science. This has led me into a wide variety of "spare time" projects. Alas, over the years and a number of moves many have been forgotten and still more have been lost, but I thought I'd post some images of a few of them, for your entertainment.

The Dream Catcher

Emotional trauma can leave victims psychologically damaged. To treat this, it helps to know what patients are really thinking, and dreams can be utilized as windows into the mind. This project was an attempt to automate the on-the-spot collection of dream information for later analysis by the psychologist or psychiatrist.

The Body Monitor PX

Millions of dollars and untold misery is the price of decubitus ulcers. More commonly known as "pressure sores" or “bed sores," these horrible wounds victimize the bedridden and those who are incapable of moving about as healthy people do. This project was a proof-of-concept prototype designed to provide an objective measurement of the care that ulcer-prone are receiving.

Automatic Bone Cancellation for CT Angiograms

The Circle of Willis is a ring-shape structure of blood vessels that sits at the base of the brain. It is both a critical part of the system that delivers blood to the brain, and apparently, a common site of aneurisms. Advanced medical imaging techniques like Computed Tomography (CT scanning) can reveal an aneurism, but not without the manual editing of image data in order to remove bone images that might block the doctor’s view. This project represents an experiment designed to automate the cancellation of bone in CT Angiogram images.

Old Robots Don't Die, They Fade Away

Over the years, I've tinkered with several homebrew robots. Most of what I've done is now dust in the wind, though I recently found a faded photograph of an early model.

A Sound Idea: Equipment For Measuring Room Acoustics

If you want to hear music or television audio the way it was meant to be heard, it is necessary to to understand how the physical attributes of a room color the sound produced by your speakers. This project, in conjunction with software, is used to measure and characterize these attributes.

Steampunk Telegraph Lights: Make Your Own Landscape Lighting

Our new pavers were in and the entrance to the house looked beautiful... that is, until night fell. In the darkness, a step becomes treacherous, a cactus, dangerous, and the mood, uninviting.  We could have purchased and installed some off-the-shelf landscape lighting, but after some research and a little bit of experimentation, I combined century-old telegraph insulators with modern white LEDs to create an eye-pleasing yard lighting solution.

Spiked Punch: Building A High Speed Automatic Computer Card Punch

Almost three decades ago, while still in high school, I designed a system of hardware and software to interface a then-brand-new TRS-80 Model I microcomputer to an IBM 029 Keypunch machine. Recently, an old friend confided that he had come across this now-ancient interface and promised to ship it back to me. What was the point of that project? How was it accomplished? What does an early example of "computer hacking" look like?.

Kella's Barbie Horse Wagon

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. Why not build one for your kids?

Kaden's Guitar

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.

A Vaccine Against Telemarketers?

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.