Substrata Communications

Benjamin Franklin is credited with many inventions; scientific experiments and discoveries; writings on science, government, and fiction; skills as an orator and diplomat; printer of books and newspapers; business endeavors; and for being the nation's first Postmaster General. Although we all are familiar with his forays into things electrical in nature like flying kites in lightning storms, this article from a 1968 issue of Popular Electronics introduces us to what might have been the earliest "wireless" communications demonstration. The scheme involved the equivalent of the old lab gag of charging up a large-valued electrolytic capacitor and then tossing it to someone, resulting in a surprising shock. As with many of you, I have been both the victim and purveyor of said mischief...

Resistive? Inductive? or Capacitive? Quiz

Here is a different type of quiz from Popular Electronics magazine's master quiz-maker, Robert P. Balin. In this October 1960 challenge, rather than the typical format where you need to match a word or another picture with a picture, this one requires you to consider each description and decide whether it best describes an inductive, capacitive, or reactive circuit. I confess to messing up on question 20, because I couldn't remember whether a lagging power factor referred to voltage lagging current or current lagging voltage. Hint: It refers to current lagging voltage. Another hint: Remember the ELI the ICE man mnemonic...

POPULAR ELEComics - Comics with an Electronics Theme

Always a good way to end a busy week, here is a collection of electronics-themed comics that appeared in a 1967 issue of Popular Electronics magazine. A few of the artists you will recognize if you are a regular reader. Some drawing styles are immediately identifiable, such as those by Dave Harbaugh (of "Hobnobbing with Harbaugh" fame). Others, at least to me, are not quite so familiar. Frank Tabor, George White, Stan Fine, and JAS (I'm sure I know those initials, but can't place them) are amongst the others. I have to admit to not really knowing what the gag is in the comic with the guy in his pajamas. The party guy is cutting a wire to his ear buds...

Technical Headlines Crossword Puzzle for August 11, 2019

This RF Cafe Engineering & Science Crossword Puzzle contains at least 10 words from headlines posted on the homepage during the week of August 5 through August 9, 2019 (marked with an asterisk*). These custom-made engineering and science-themed crossword puzzles are done weekly for the brain-exercising benefit and pleasure of RF Cafe visitors who are fellow cruciverbalists. Every word and clue - without exception - in these RF Cafe puzzles has been personally entered into a very large database that encompasses engineering, science, physical, astronomy, mathematics, chemistry, etc. Let me know if you would like a custom crossword puzzle built for your company, school, club, etc. (no charge)...

Who Killed the Signal?

If you're a newcomer to the game, it may seem that radio theory already has enough mystery without adding more. True, the technical journals - even QST, sometimes - do make it a mysterious subject with their textbook language and complex notations. Radio isn't really any more mysterious or complex than many a detective story - at least not after you've read the last page and know "who­dunit." The difference lies in the method of presentation. There may be some utility, then, in the idea of presenting radio fundamentals in the manner of detective fiction. That's what this is - a series of radio lessons in the guise of a detective-mystery yarn. Instead of human characters we'll use another kind - but we'll try to make the characterizations true and the background and incident realistic. Our purpose is to divert...

Geniac Problem Solving Computer

I remember seeing advertisements for the "Geniac Electric Brain" in technical magazines like Popular Electronics, Mechanix Illustrated, Popular Science, etc., back in the 1960s and 70s. Even then it seemed like a hokey attempt to pitch a mechanical gizmo as an honest-to-goodness computer. Personal computers were still a decade or more away and only multi-million-dollar mainframe computers were available, so the opportunity for Joe Sixpack to own a "problem solving" computer was a real temptation. No, I never bought one; my first computer was a second-hand Timex Sinclair 1000 with a membrane keyboard and a cassette tape deck as a program storage device. Anyway, when I found this article in a 1966 issue of Popular Electronics, I figured maybe other people of my vintage would enjoy reading about its inner workings...

Generators, Electricity - Basic Navy Training Courses

In keeping with a very common practice of using water flowing through a garden hose as a teaching aid analogy for newcomers, the title of this chapter of the NAVPER 10622 Basic Navy Training Courses, "Generators - Electrical Pumps," is likening electrical generators to water pumps. It is an apt analogy, but whereas a water pump can cause water pressure and flow of a physical substance already on-hand, electrical "pumps," aka generators, literally creates its "flow" from thin air (even a vacuum with no air). An electrical generator exploits the phenomenon discovered by (or at least credited to) Michael Faraday whereby a conductor moving through a magnetic field - or a magnetic field moving past a conductor...

Mac's Radio Service Shop: New Uses

If there was another episode of Mac's Radio Service Shop where Barney was the primary teacher and Mac was the student, I don't remember what it was. In fact, this is about as total of a role reversal as there can be. First, Mac admits to having chased a presumed oscilloscope issue down the proverbial rabbit hole only to realize the cause of the problem was totally unrelated. Then, Barney produces a nifty device meant for recording telephone conversations and demonstrates to Mac a couple ingenious applications he discovered that were handy for troubleshooting television sets. When reading Mac's description of using a magnet to alter the electron beam in a CRT, it reminded me of how cool it was on the CRT displays to run a magnet...

The Secret Keepers

RACEP (Random Access and Correlation for Extended Performance), was an early form of frequency hopping spread spectrum (HFSS) devised by the Martin Company (now Lockheed-Martin). It was used for secure voice communications and worked by sampling speech in small 'slices' and then transmitting each slice modulated onto a carrier whose frequency was determined by a predetermined sequence of center frequencies. A receiver with a matching sequence key would then decode the speech and, with appropriate filtering, reassemble it into its original content. President John F. Kennedy had such systems at his disposal whether on the road or in the Oval Office. General Electric (GE) had a different idea it dubbed 'Phantom' that spread the signal over a very wide bandwidth. Today, we refer to it as Direct Sequence Spread Spectrum (DSSS)...

How to "Arrest" Lightning

Before the advent of electrical distribution systems and electronics, the hazard of lightning was primarily from fire ignition and, to a lesser extent, bodily injury (to humans and animals). In fact, it was Benjamin Franklin's discovery that lightning was a form of electricity that led to his subsequent invention of the lightning rod system that, after being installed on Philadelphia's tallest wooden structures, significantly reduced the incident of lightning-related devastating fires which had been ravaging the city for years. Once cities began installing electric power lines, they were to lightning what trailer homes* are to tornadoes - strong attractors. Line protection systems were soon developed to help stop strikes which sometimes caused electrocution to people inside homes who happened to be touching a light switch or plumbing fixture...

Using the Varicap

You and I know them as 'varactor diodes,' but originally the semiconductor junctions whose reverse bias determines its capacitance was called the 'Varicap.' The new and wondrous semiconductor craze was in full swing by 1958. Scientists, engineers, and hobbyists were burning the midnight oil (to use a popular phrase of the day) performing experiments and designing circuits to replace vacuum tubes and manual controls with transistors and other electrically variable semiconductors. The Varicap had the ability to tune receiver and transmitter oscillators and filters without the need for high tube bias voltages and large mechanically variable multi-plate capacitors. This article from Radio-Electronics says early Varicaps cost $4.50 apiece...

Planning to Be an Electronic Engineer?

This article from a 1955 issue of Popular Electronics magazine describes my evolution from electrician to electronics technician to electronics engineer. For that matter, it describes the paths many people I have worked with over the years have taken. My mentor at my first job as an RF engineer after graduating with a BSEE from the University of Vermont began as a technician in the Army, and then he went to school part-time while working a full-time job to earn his BSEE. In my next job as an RF engineer there were at least two guys I knew who had also taken that path. Although not by any means absolute criteria for judging an engineer's enthusiasm, I will say that at least as a distinct segment of RF engineering, those who are amateur radio operators and/or those who began life as a technician...

RF Cafe Quiz: Archaic Scientific Words & Definitions

This particular quiz tests your knowledge of archaic scientific words & definitions. Choose the best answer for the spirit of the quiz; i.e., the one that represents the newer term or the abandoned definition. All RF Cafe quizzes would make perfect fodder in employment interviews for technicians or engineers - particularly those who are fresh out of school or are relatively new to the work world. Come to think of it, they would make equally excellent study material for the same persons who are going to be interviewed for a job...

Comic with an Electronics Theme, May 1955 Popular Electronics

If you are familiar with Carl Kohler's illustrations from his numerous humorous (a rhyme!) electronics-themed stories in Popular Electronics magazine, then this comic from the May 1955 issue will be recognized as having come from his hand. The 1950s through maybe the early 1980s was a big time for do-it-yourself hobbyists of all sorts, including those who dabbled in electronics as Hams, household handymen, kit builders, etc. In many cases high quality products could be purchased more cheaply as kits, as evidenced by the popularity of Heathkit and similar companies. By the mid to late 1990s, super-cheap labor - verging on slavery - in the Far East was doing the majority of component production and product assembly, so eventually an inversion...

Engineering & Science Crossword Puzzle for August 4

This RF Cafe Engineering & Science Crossword Puzzle contains at least 10 words from headlines posted on the homepage during the week of July 29 - August 2, 2019 (marked with an asterisk*). These custom-made engineering and science-themed crossword puzzles are done weekly for the brain-exercising benefit and pleasure of RF Cafe visitors who are fellow cruciverbalists. Every word and clue - without exception - in these RF Cafe puzzles has been personally entered into a very large database that encompasses engineering, science, physical, astronomy, mathematics, chemistry...