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 Electromagnetism is
the force that governs the behavior of charged particles and the propagation of
electromagnetic waves, forming the physical basis for nearly all modern
electronic and wireless communication systems. From the fundamental observations
of Oersted and Ampere to the elegant synthesis of Maxwell's equations, the field
describes the inseparable relationship between electric and magnetic fields.
Whether it is the Lorentz force propelling an electron beam in a vacuum tube,
the induction driving a power transformer, or the alternating fields that carry
radio signals across the globe, electromagnetism is ubiquitous. This
Electromagnetism Quiz explores the core concepts of this discipline...
 Popular comic strips (aka "funnies") in
the 1930s and 1940s featured numbskulls, ne'er-do-wells, and simpletons. There was
usually one character in the strip's cast that was smart - at least in a relative
way if not absolute. Being familiar with some of the old comics like Blondie, Barney
Google, Krazy Kat, Beetle Bailey, Gasoline Alley, etc., I can see a definite relationship
between the story line of "Entertaining
Uncle Oscar" and the comics of the era in this short story that appeared in
a 1939 edition of the ARRL's QST magazine. As you might guess, the
feller named "Ham" is the smart one. Q: Is it irony, coincidence, or premonition
on the author's part that the uncle's name is the same as...
 If you are going to write an article about
etching crystals for radio frequency circuits, having a last name
like Gene Brizendine's couldn't be much better. It just sounds like a mineral
or a compound (benzidine, etc.). Amateur radio operators have for a long time adjusted
the resonant frequency of their crystals by either grinding or chemical etching.
Mr. Brizendine recommends etching as a more controllable method that does not
reduce the quality of the crystal like improper grinding can do. Ammonium bifluoride
is mentioned as the etchant. It is said to have cost about $1/pound in 1954, and
sells on Amazon today for about $23/pound. According to the BLS Inflation Calculator,
$1 in 1954...
 Working crossword puzzles can be contagious.
This April 12, 2020,
tech-themed crossword puzzle may even go viral - the second in
a series. It contains only clues and terms associated with engineering, science,
physical, astronomy, mathematics, chemistry, etc., which I have personally built
over nearly two decades. That includes the cause for our planet's current dilemma.
Many new words and company names have been added that had not even been created
when I started in the year 2002. You will never find a word taxing your knowledge
of a numbnut soap opera star or the name of some obscure village in the Andes mountains.
You might, however, encounter the name of a movie star like Hedy Lamarr...
 Werbel Microwave is a manufacturer of
RF directional and bidirectional couplers (6 dB to 50 dB) and RF power
dividers / combiners (2- to 16-way) with select models operating up to 26.5 GHz
and 100 W of CW power (3 kW peak). All are RoHS and REACH compliant and
are designed and manufactured in our Whippany, NJ, location. Custom products and
private label service available. Please take a couple minutes to visit their website
and see how Werbel Microwave can help you today.
 Transformers are the workhorses of power
distribution and signal processing, utilizing Faraday's law of induction to step
voltages up or down while maintaining high efficiency. By coupling magnetic fields
between primary and secondary windings through a shared core, they provide critical
electrical isolation and impedance transformation between circuit stages. From massive
grid-scale power units to tiny high-frequency RF baluns, transformers must manage
complex phenomena such as magnetizing current, eddy current losses, hysteresis,
and parasitic leakage inductance. This quiz explores the core physics behind transformer
operation, including the “turns ratio” relationship, the role of core...
 A column entitled "Radio-Electronics Monthly Review" appeared in each issue of Radio-Craft
magazine. As now, things were moving quickly at the time. With WWWII recently ended,
a lot of the new technology developed to help beat back Nazism and Communism was
being transferred to peacetime uses. The May 1947 issue contained, amongst other
items, info regarding how radio servicemen were organizing efforts to get its ranks
educated on FM sets as AM was being replaced and/or supplemented with the new miracle
noise-free broadcast systems. It also reported that the IRS decided not to go forward
with earlier plans to tax television shows being displayed in public...
 Radio control (R/C) systems operating in
the 2.4 GHz ISM band, using one of or a combination of frequency hopping and
direct sequence spread spectrum scheme, have been in widespread use since the early
2000s. As with any new technology, there was a lot of reluctance to adoption of
the systems based on a few reports (valid or not) of performance issues - primarily
lack of control range where communications between the transmitter (Tx) and receiver
(Rx) with a pilot and aircraft was lost and a crash ensued. Tx power was already
at the FCC-mandated maximum, so manufacturers quickly improved receivers by adding
diversity with a second Rx antenna. The receiver...
 As reported in this 1967 Electronics
World magazine piece, lasers were still the things of science fiction to most
people. Real-world applications seemed to be far off in the future, but in fact,
work was underway setting the stage for today's blazingly fast communications
systems. The author here references attaining 5 THz optical transmission speeds
through fiber and through the air. At the time, a laboratory filled with bulky prototypes
chassis and optical tables were required to get those results. I can remember reading
articles in the 1970s when laser power output was measured in "Gillette power," referring to the beam's ability to burn through
a number of razor blades (a big deal...
 If my counting is correct, by 1952 only
33 of America's 48 states (Hawaii and Alaska weren't admitted until 1959),
and Washington, D.C., had
television broadcasting stations. That most of the early television
experimentation occurred on the east coast is apparent by looking at the number
of stations there compared to the west coast. You might think California would have
the largest amount of TV stations, but it only had 11 located in 3 cities. New York,
on the other hand, had 13 in 7 cities. Ohio had 12 stations in 5 cities, and Pennsylvania
had 7 stations in 5 cities, one of which was my town of Erie. Vermont, New Hampshire,
Mississippi, Wyoming, both Dakota, and Oregon were among...
 By now, engineers and scientists have managed
to replace most vacuum tubes with solid state devices - at least for consumer products.
The one place tubes remain are in microwave oven. Those klystron tubes operate in
the 2.4 GHz band and typically output ranging from about 500 W to 2 kW.
No doubt materials and methods have changed since the 1950s, but fundamentally klystrons
of today are the same as klystrons then. Between this article and Part 1 that
appeared in the April 1952 issue of Radio & Television News magazine,
authors Joseph Racker and Lawrence Perenic provide a very nice introduction on the
topic. According to the Wikipedia entry, the name "klystron"...
 The U.S. Army's Signal Corps was set
up to "exercise supervision over signal communications literally from the Pentagon
to the foxhole." Created in 1860 at the suggestion of a military doctor, the
Signal Corps originally used a system of flag waving for messaging
dubbed "wigwag" and graduated to overseeing the nationwide telegraph network six
years later. By 1870, members were tasked with establishing and operating a weather
forecasting service, so in 1907 when they created an aeronautical division it was
just in time for facilitating the nation's rapidly growing cadre of aircraft
pioneers by providing en route weather information. Having already mastered the
state...
 I have never seen study-at-home audio-visual
(AV) physics courses offered by Albert Einstein or AV courses on chemistry promoted
by Ernest Rutherford, but I can now say I have seen study-at-home AV courses offered
by electronics pioneer Lee de Forest. This full-page advertisement for the
de Forest's Training, Inc., company of Chicago, Illinois,
appeared in a 1945 edition of Radio-Craft magazine. The vaunted (at least
by the company) "Syncro-Graphic" training was an early attempt at the paperless
classroom. The student watched films reels of instruction rather than "frequent
flipping of pages to refer back or ahead to illustrations mentioned in text." It
would be another 50 years before...
 The history of electrical current is replete
with tragic incidences of maiming and death caused by ignorance and/or inattention
to known danger. Having been involved in both the electrical wiring and the electronics
fields since the 1970s, I am quite aware of the legion of hazards present when current
flows. My tool box contains screwdrivers and lineman's pliers with notches of
melted metal from inadvertent contact between differences of potential in circuit
breaker panels and electrical wall boxes. Once you experience the thrill of a sudden
blinding flash, unique buzzing sound, and smell of burning hot steel, you'll
never forget it. A lot of people have been
electrocuted, though, through no fault...
 Less than half a decade had passed when
Radio & Television News editor Oliver Reed wrote this piece extolling the
virtues of the transistor and how "it may well revolutionize the
entire electronics industry." If you have followed a lot of my postings from the
vintage electronics magazines here on RF Cafe, you are well aware that there
was a lot of resistance to and doubt about the future of semiconductors. Naysayers
had the same kind of reaction to the advent of the horseless carriage (automobile)
and locomotive, relativity and quantum mechanics, and even curative medicines. Point
contact transistors were still largely in use, but were costly compared to the relative
simplicity and low...
 Please take a few moments to visit the
everything RF website to see how they can assist you with
your project. everything RF is a product discovery platform for RF and microwave
products and services. There are currently 374402 products from more than 2667 companies
in the database, and engineers can search using a customized parametric search tool.
Also 5482 technical articles. Amplifiers, test equipment, power couplers and dividers,
coaxial connectors, waveguide, antennas, filters, mixers, power supplies, and everything
else. Please visit everything RF today.
 Inductance is a fundamental property of
any conductor, representing its ability to store energy in a magnetic field when
current flows through it. From the simple air-core loop to complex multi-layer transformers,
inductors are essential for filtering, impedance matching, energy storage, and signal
processing. Unlike capacitors, which resist changes in voltage, inductors resist
changes in current, governed by the classic relationship of electromotive force
being proportional to the rate of change of current. This quiz delves into the behavior
of inductors in both AC and DC circuits, the variables that define their magnitude
- such as core material permeability, number of turns, and geometry...
 Albert Einstein published his paper on
Special Relativity in 1905 and on General Relativity in 1916.
Since that time, many experiments have been performed worldwide by scientists intent
on both proving and disproving Mr. Einstein. Laser and nuclear based timepieces
have been improved for precision and calculations refined to aid in the task. This
1959 Popular Electronics magazine article reports on one of the first atomic
clock experiments used to test General Relativity. After more than 100 years, General
Relativity stands as originally presented. Even the rigors of quantum mechanics,
which Einstein did not embrace until much later in life, has not toppled its precepts...
 Even in this time of readily available computers
(including your smartphone) and printers, having a set of
rubber stamps for common electronics symbols would be pretty handy;
there are some Neanderthals among us who still use pencil and paper on occasion.
Simpler symbols like resistors and capacitors are easy enough to sketch by hand,
but something like a dual gate MOSFET with diode protection can take some time to
produce legibly. Common connector types like the DB signal/power series and some
RF kinds (BNC, SMA, etc.) would be useful, as would a set of oft-used logic gates
for the digital designers. The set shown here in a 1953 edition of Radio-Electronics...
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The RF Cafe Homepage
Archive is a comprehensive collection of every item appearing daily on this
website since 2008 - and many from earlier years. Many thousands of pages of unique
content have been added since then.
 When the electronics product world consisted
of vacuum tube based circuits, the physical sizes of standard fixed-value passive
resistors, inductors, and capacitors were not of much concern in terms of
how much volume they consumed. R's, L's, and C's, had wire leads protruding from
their molded bodies, or in the case of larger power supply filtering capacitors
had solderable tabs. Point-to-point wiring consisted of components and hookup
wire suspended in the air between solder terminal strips and tube base tabs.
Even with miniature (peanut) tubes, all but the largest passives had no
significant impact on overall unit size. Once semiconductors came onto the
scene, everything changed. Suddenly, even the standard 1/4 W carbon resistor and
tantalum capacitor became a significant factor when attempting to reduce size...
 This photo of
Ray Dolby holding one of his prototype noise reduction circuits is probably
the most widely published of him and therefore the most iconic of the Dolby noise
reduction system. Audiophiles of the era (and today for that matter) immediately
recognize the man who took the hisses and pops out of their beloved music. I always
like to keep in mind when reading article like this one in a 1971 issue of Radio-Electronics
magazine is that when it was originally published, Dolby had not yet become a household
word and news of his accomplishment was just getting out. Many articles, books,
and research papers have been written on how the Dolby system works. At least five
of them from the groundbreaking era have been posted here on RF Cafe, so you can
get some insight into the excitement. The technical term "companding"
(compressing and expanding) was being seen in print for the first time...
 Here is another electronics
challenge for you to try - the "Resistor
Function Quiz." It covers basic functions of resistors in various circuits. The
quiz appeared in the January 1962 edition of Popular Electronics
magazine, compliments of
Robert P. Balin. I got 100%, just for the record - PhD not required, by the
way. Having worked with tubes in the days of yore helps with figure B since it does
not really have a direct transistor equivalent, but by process of elimination you
can get it...
 Since 2000, I have been creating custom
technology-themed crossword puzzles for the brain-exercising
benefit and pleasure of RF Cafe visitors who are fellow cruciverbalists. The
jury is out on whether or not this type of mental challenge helps keep your gray
matter from atrophying in old age, but it certainly helps maintain your
vocabulary and cognitive skills at all ages. A database of thousands of words
has been built up over the years and contains only clues and terms associated
with engineering, science, physical, astronomy, mathematics, chemistry, etc. You
will never find a word taxing your knowledge of a numbnut soap opera star or the
name of some obscure village in the Andes mountains...
 The problem of and concern about our country's
youngsters seemingly not being overly interested in
pursuing technical career paths is a theme often heard in the tech news
media and workplaces. As our world grows increasingly automated and everything
from light bulbs to telephones and automobiles are so packed with "no user
serviceable parts inside," there seems to be little motivation for an otherwise
potential budding tinkerer to take stuff apart to discover what makes it work.
In the "old days" like, say, 1955, products were much more accessible to kids'
curious nature and explains why fostering the next crop of engineers,
scientists, and technicians took care of itself. You might think so, but alas,
the dilemma evidently persists with each succeeding generation...
 Here is a fairly simple
quiz on AC circuit analysis. If you are not already comfortable with adding
series and parallel circuits containing resistors, capacitors, and inductors, you
will appreciate the simple formula presented that will keep the sweat level down
;-) . An even simpler form that solves explicitly for the four variables are
as follows: VTotal = √ [(VL - VC)2
+ VR2]
VR = √ [(VT)2 - (VL - VC)2]
VL = VC + √ [VT2 - VR2]
VC = VL - √ [VT2 - VR2]
OK, pick up your pencils... now...
 Back in 2012, I posted a video of the PBS
"Frontline" show (Cell Tower Deaths) that highlighted the dangers cell tower climber
technicians face while working for very low wages. Other news stories since then
have reported on new regulations from OSHA and other agencies that have helped make
the safety issue better, but I haven't seen anything on whether the pay has gotten
any better. There are lots of videos and photos online of
tower climbers
all over the world, but this one showing tower climber Kevin Schmidt making the
ascension to the very top of the now inactive KDLT TV analog broadcast antenna
near Salem, SD, is unique in that the recording was made from a drone platform.
It has more than 12 million views. Capturing this kind of video requires a drone
with a wireless live feed so the pilot...
 An alternate title for this article that
appeared in a 1969 issue of Radio-Electronics magazine could have been,
"How
to Build a J-K Flip-Flop." Author Leonard Geisler takes the reader through a
step-by-step assembly of a functional J-K flip-flop using a collection of 1- 2-
and 3-input NAND gates. The 1-input NAND, in case you are wondering, is used as
an inverter. The piece reads like an in-depth first-semester electrical engineering
technician course textbook. In the process of building the J-K, an R-S (reset/set)
flip-flop is described. Nowhere does Geisler offer an explanation of from where
the "J" and the "K" input labels come. According to electrical engineer Sourav
Bhattacharya blog, it was Dr. Eldred Nelson of Hughes Aircraft who first coined
the term J-K flip-flop...
 This you need to see. The full story behind
this video is unknown, but supposedly customers were complaining about poor reception
associated with the Bear Creek Road microwave station somewhere in northern California.
Upon inspection, the technicians discovered a small hole in the radome. When the
cover was pulled away, according to the video somewhere between 35 to 50 gallons
of
acorns
spilled out. You can see the bulge in the radome before emptying. The tech
probably thought the water drain hole was clogged and it was full of water. From
a National Geographic story: "Walter Koenig, a senior scientist with the Cornell
Laboratory of Ornithology, says he's pretty sure the the acorn woodpecker..."
 The term "ovonic" - a fairly unfamiliar word
these days - appeared in the May edition of Radio-Electronics, in an article
entitled, "All About Ovonics," just a few months after this news item ran in the
January issue (which I posted last month). Ovonics is a portmanteau of "Ovshinsky"
(from Stanford R. Ovshinsky, the inventor) and "electronics." Read the "All About
Ovonics" article for a deeper dive into the subject. The big deal, which turned
out to be not a big enough deal, was the use of
amorphous "glassy" compounds as semiconductors rather than the standard
crystalline silicon structures. Maybe someday an enterprising genius inventor
type will give a rebirth to the concept...
 One of the monthly columns in R/C Modeler
magazine, written by Chuck Cunningham, entitled "Cunningham on R/C," that reported
on the current state of radio control, which had only fairly recently evolved into
fully solid state, proportional control systems. Anyone involved in electronics
is painfully familiar with the weird kinds of issues that crop up in complex circuits
that operate in hostile environments. The March 1970 issue contained part of an
article authored by D. L. Klipstein, Director of Engineering, Measurement Control
Devices, entitled, "Murphy's Law: The Contributions of Edsel Murphy to
the Understanding of the Behaviour of Inanimate Objects.*" Only a few of the
items were printed in Cunningham's column, but I managed to locate a copy of the
full article...
 This is a story with a lesson learned by
the author and thousands of others ever since electric power appliances and tools
first became available. Fortunately, his Ham buddy was not permanently harmed, but
even today with all the effort put into educating the public, people continue to
use ungrounded (2-wire type, or with the ground prong removed) extension cords in
conjunction with 3-wire power cords on tools and end up
electrocuting
themselves (or somebody else). I've told the story before about a friend of mine
from high school who shortly after graduation was making a piece of furniture in
a garage that had a damp dirt floor, and was electrocuted to death by the
metal-framed circular saw that had no ground connected. Nowadays we often have
power provided by a GFCI receptacle...
 "Rediscovery
of FM Broadcasting" could be a contemporary headline. The decline of
broadcast radio has been a major concern of station owners for well over a
decade since Internet and satellite radio has dominated the venue through which
listeners access radio stations. Local broadcasters have long aired syndicated
programs that include national advertising, but the money to pay for those
segments came from revenue supplied largely by local companies. FM broadcasting
began commercially around 1945 in the familiar 88-108 MHz band yielded by the
military following World War II, and grew in number of stations very rapidly in
the first few years. Then, it began a decline for a few more years until finally
leveling off after about a decade. Even though FM had a clear advantage
(literally) over AM because of electrical noise immunity...
 My daughter, Sally, in addition to owning
and operating a very successful horse riding school named Equine Kingdom Riding
Academy, has a rather large eBay store she uses as a venue for selling items purchased
at the local Goodwill "Bins" store. She often buys vintage toys with electronics
features - sometimes working and sometimes not. A properly functioning vintage toy,
be it a stuffed animal or a game of some sort, can make a huge difference in the
resale price. When that is the case, she sends them home with me to attempt a repair.
Many times the problem is corroded contacts from leaky batteries. A dental pick
and some isopropyl alcohol usually solves the problem. When that doesn't work, it's
time to open 'er up for a deeper look. Over the years I have found problems
ranging...
 All college curricula seem to have a number
of particular "weeding out" courses that cull the herd - so to speak - from the
eventual graduating class. The unfortunate victims are then faced with either dropping
out of college (not always such a dooming fate) or choosing a different major. For
mechanical engineers (MEs) it was often statics; for electrical engineers (EEs)
it was
AC circuits - the topic of this article. DC is relatively simple because
voltage and current is always in phase, thus no "hard" vector math is involved,
but throw in reactance with its attendant non-zero phase angles and suddenly the
student is faced with trigonometry - the kiss of death to mathphobes. My experience
in engineering school showed that for MEs who lived through statics, dynamics provided
the next level of weeding out (it nearly got me). For EEs it was Fourier and Laplace
transforms. Level three for MEs was thermodynamics (thermogodda**ics was a
popular alternate title)... |
