Interesting Oscilloscope Patterns

Over the Independence Day Weekend, I spent some time with my vintage Tektronix 7614 o’scope looking at various ways to generate “pretty pictures”. My goal is to get some of this documented in a way that allow easy demonstrations and such. This, in turn, might help interest other people in the radio and electronics hobby.

I have posted a video with some of the results on YouTube.

One very useful piece of equipment that made life a lot easier was a Samsung tablet running the audio function generator software app available from Black Cat Systems. The output level on the tablet was a bit low, so I built a dual 5x amplifier using a 1458 dual op-amp chip. After that I was in business and able to generate some interesting patterns. Most were “stable”, but the last example in the video actually shows a primitive demonstration of what the output from an analog computer looking at the orbit of the moon around the earth as the earth orbits around the sun might look like. (In other words, it shows a “dual orbit” on the o’scope screen.)

I hope to be sharing more soon!

73 de

“With a schematic in one hand, a soldering iron in the other, and a puzzled look on his face”


More QRP and the Oscilloscope

I am excited to say that my latest book, Oscilloscope Applications for the QRP Enthusiast, has been released into the wild (or at least release on Amazon)…

Oscilloscope Applications for the QRP Enthusiast

I am working on a few other projects right now. For a while now I have been pulling together bits and pieces for a book on the restoration of vintage shortwave sets and I plan to work on that through the summer. I also have a few more ideas about oscilloscope applications that I think people might find interesting–more to come on that over the next few weeks.

73 de

“With a soldering iron in one hand, a schematic in the other, and a puzzled look on his face…”

QRP and the Oscilloscope

This weekend I have been working on projects related to a book about using the oscilloscope to characterize and evaluate simple QRP transmitters. I’ve built a simple test jig that will let me do most of the testing I will be discussing in the book.

QRP Transmitter Test Jig

It includes everything needed to key the transmitter with a string of dits, provide a dummy antenna, and regulate the power supply (in a way that allows measurement of the DC input power).

I’ve gathered most of the test data to characterize my Tuna Tin 2 QRP transmitter.

Tuna Tin 2 QRP Transmitter

The results and the book should be out in a few weeks.

73 de

“With a soldering iron in one hand, a schematic in the other, and a puzzled look on his face…”

Hello and Welcome!

Let me make a quick introduction of myself and this blog.

I am Jim, W4JBM, and first began tinkering with radios when I received a crystal radio kit for Christmas at the age of 6 back in 1969. I have been hooked on radio, electronics, and (later) computers as both a hobby and a career ever since.

While I enjoy reading (on technical as well as other topics), I also enjoy the “hands-on” aspects of experimenting, building, and repairing gear. My Radio Shack 150-in-1 lab saw use all the way into college when it was largely replaced by my Heathkit ET-3100 experimenter’s breadboard.

As a teenager, All American Five vacuum tube receivers were plentiful and cheap at flea markets and garage sales. (I remember once picking up a box of over a dozen for a quarter–and being able to get most of them working again.) I have no idea how many I repaired, but it would be several hundred with probably around another hundred more being sacrificed for the parts needed to repair others. I would also end up building several simple shortwave sets including a three transistor regen kit offered by Radio Shack and, eventually, a Heathkit SW-717.

In 1980 I received my first computer  (an Ohio Scientific Instruments C1P) as an early high school graduation gift. Those were the early and exciting days of personal computing and I dove in with both feet experimenting and learning with both hardware and software. One achievement that stands out was a “programmable” computer built entirely from 7400 series TTL logic chips as a lab project in college. It had a 16 byte program space (consisting of 16 8-pole DIP switches that served as a primitive EPROM) along with four registers. We had to “write” and demonstrate a program that could load and multiply two four-bit numbers. We got bonus points for being able to write programs that would square a four-bit number and divide two four-bit numbers (with the result in one register and the remainder in another). I remember it also becoming an exercise in power supply construction once we passed the 1 amp capability of the power supply the school gave us along with a bag of ICs when we started the project.

This blog will consist of several types of content. I intend to primarily focus on hints and tips related to radio and electronics that I have picked up over the years. There will also be some reminiscing (and maybe even a bit of bragging) along the way. I will also post information related to the various books I have written and that are available from Amazon along with an occasional magazine article.

Until later!!!

73 de

“With a soldering iron in one hand, a schematic in the other, and a puzzled look on his face…”