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 RF Cafe visitor Paul A. sent me a link to this video of a rotary
spark gap transmitter that was on display a the 2010 Dayton Hamvention. The hand-crafted
replica is a work of art. Jim Stafford, W4QO, provided the demonstration during
the Early History of Ham Radio Forum. "A spark-gap transmitter is a device for generating
radio frequency electromagnetic waves using a spark gap. These devices served as
the transmitters for most wireless telegraphy systems for the first three decades
of radio (1887–1916) and the first demonstrations of practical radio were carried
out using them. In later years (prior to the development of practical vacuum tube
systems) somewhat more efficient transmitters were developed based on high-speed
Alexanderson alternators and Poulsen Arc generators, but spark transmitters were
still preferred by most operators." <Wikipedia>
4/19/2011
 Near Field Communications (NFC) is still a
fairly fledgling technology in term of adoption its capabilities. On nearly a daily
basis, I search tech websites for news that includes noteworthy articles on NFC.
One such website is
NFC World, which is where I found this item. In it, two students from Stanford
University's MobiSocial
project give a live presentation of the way near field communications can be used
to adapt appropriately equipped appliances for use. Linking of devices is accomplished
by placing two or more within the coupling range of the NFC coils (using magnetic
induction between loop antennas), then software allows communications between, and
manipulation of the devices. NFC operates at 13.56 MHz, with data rates from 106
kbit/s to 848 kbit/s. There are already many commercial applications that have already
adopted NFC, including ticketing, vending machine payment, P2P software apps, and
even some personal identity cards. <more>
3/1/2011
 Can you be nostalgic for a time in which you
never lived? When I watch these old films of production lines back in the 1930s
and 1940s, it makes me long for the days of America being a manufacturing powerhouse.
When I worked at the former GE plant in Syracuse, NY, I used to walk around some
of the long-closed buildings that at one time were a beehive of activity producing
TVs, washing machines, and clock radios, and wonder what it would have been like.
This video titled Electrons on Parade
was produced by RCA sometime around 1942. It is amazing how labor-intensive the
process was. The automated machines are equally impressive for the precise operations
performed without the benefit of microprocessor-controlled stepper motors and a
nice LabView® software interface. Notice that the majority of production line workers
are women who, as a class, made a move from fulltime housewives to essential workers
to satisfy needs made necessary by the war effort since the men had gone off to
battle against Axis powers. Rosie the Riveter was <more>
2/22/2011
 Videos of radio
tower climbers are
cool for sure. Fear of heights notwithstanding, the physical strength and stamina
required to scale 1,000+-foot towers is more than most people could endure.
Winds aloft are typically stronger and more gusty than at ground level, so the shaking
of the tower would unsettle all but the most robust stomachs and inner ears. Their
bravery helps assure that communications worldwide continue nearly uninterrupted.
There is another cadre of aerial linemen that deserve attention - the guys who ride
on helicopter skids to maintain and repair high voltage transmission lines. One
of the coolest parts of the video is where the lineman uses a metal wand to draw
an arc from the power line (often at 100 kV or more) in order to bring the helicopter
environment to the same potential <more>
4/26/2011
 12-year-old boy genius Jason Barnett is shown
here giving an integration by parts lesson on his bedroom window. Yeah, we all used
to do that at 12. Jason began studying astrophysics at 3, plays classical music
from memory on the piano, and had memorized pi to 200 places - forward and backward.
He also plays Guitar Hero and has a girlfriend. Now in college at Indiana U. - Purdue
U. where he works on Big Bang theory, Jason has been tagged at the most brilliant
human ever. "When I first walked in and saw him, I thought, 'Oh my God, I'm going
to school with Doogie Howser,'" said a biochemistry major classmate. I am feeling
kinda insufficient right about now. Someone needs to put a stop to Jason's stellar
rise because according to modern teachings, it is just not fair that Jason be so
gifted when others are not - you know, the social justice thing.
3/29/2011
 MIT has long enjoyed a reputation as one of
the country's top engineering school. They were one of the first to make videos
of undergraduate classroom instruction sessions available at no cost to the public
(nothing is free - the tuition payers picked up the tab) through
OpenCourseWare. For the past few
years, hundreds of videos have been produced and posted that demonstrate various
fundamental physical processes. One cool video shows how a
Faraday cage keeps an electric
field outside the enclosure from affecting the field inside the enclosure where,
in this case E=0, and vice versa. A
Van
de Graaff generator supplies the electric field while a Ben Franklin doll with
strands of metal tinsel attached is used as the UUT (the store must have been sold
out of Michael Faraday and Robert Van de Graaff dolls). We exploit the same principle
in the form of folded sheet metal shields on PCBs all the time to keep RF energy
from interfering with other circuitry in the vicinity. Then, entire assemblies are
shielded to prevent energy from being radiated to the outside world, as well as
to keep outside world energy from influencing the performance of our circuits. <more>
3/1/2011
 Maurits Cornelis Escher, aka
M.C. Escher
(1898 – 1972), was a Dutch graphic artist known for his often mathematically inspired
woodcuts, lithographs, and mezzotints. These feature impossible constructions, explorations
of infinity, architecture, and tessellations. If you do a search on Escher's waterfall,
you will find a lot of information that explains how his methods tricked the human
brain to perceive something that is not what it appears to be. There are videos,
physical models, computer models, paintings, drawings, and written theses. Even
knowing that the image does not comport with real-life experience, figuring out
exactly how the spoof is executed can be difficult - if not impossible (to some).
In this video, a resourceful young man uses a physical model with a carefully placed <more>
5/3/2011
 The extents to which companies have to go
in order to make memorable advertisements just keeps increasing. Production costs
are high, and there is no guarantee that even the most sophisticated effort will
be rewarded with even close to a viral status. Judging by the very wide coverage
of NTT (Nippon Telegraph and Telephone Corporation ) DoCoMo's (Do Communication
over Mobile) Touch Wood SH-08C video, they seems to have a winner. You
need to watch the video to appreciate planning that went into the making. Both pitch
and tempo are carefully reproduced throughout. For those not familiar with classical
music, the tune is Bach's "Jesu, Joy of Man's Desiring."
Morihiro
Harano, of Drill Inc., was the video's creator. Unfortunately, most DoCoMo phones
only work with Japan's proprietary cell network, so you cannot get one for use elsewhere.
Some dope posted, "Anybody else feel slightly betrayed when it turned <more>
4/5/2011
 Animals are used
quite effectively in many advertising formats - the infamous yearly Super Bowl collection
is replete with them. In this video, Samsung has enlisted the aid of Welsh sheepherders
to help promote their line of high efficiency LEDs. It was released in advance of
its 2009 debut of LED televisions. Two flocks of sheep - one black and one white
- are each fitted with a battery-powered blanket of hundreds of LEDs. The skilled
shepherds and amazingly competent sheep dogs then use a highly choreographed script
to coax the sheep into mosaic forms that build pictures. One feat is an animated
(literally) sheep form that collectively walks across the hillside. When the sun
goes down, the LEDs are powered up and the sheep, among other things, emulated a
game of the old Atari
Pong video game. The coup de grâce is a mosaic of the Mona Lisa. Not baaaaaad!
3/8/2011
 Every once in a while someone upsets our
comfortable existence by pointing out inconvenient realities like the problem of
what happens to our electronics devices after the manufacturers convince us that
we need the latest version of their wonder gadget. Unlike regular household recyclables
like glass jars and cardboard cereal boxes, electronic devices contain a lot of
valuable material that makes it profitable for reclamation if the work can be performed
somewhere nobody really cares about the human costs of doing so. In China, India,
Ghana, and many other "developing" countries, poor souls earn an existence by disassembling
and performing crude processing of the components to separate heavy metals like
gold, silver, lead, cadmium, beryllium, mercury, and others. For their efforts they
sell their booty at a pauper's wage. <more>
5/10/2011
 As time goes by, we tend to take for granted
some of the innovations in both methods and materials that changed the way business
is conducted. Just as anyone under the age of 30 assumes that personal computers
have always been a part of life, and anyone under 20 thinks that cell phones are
issued at birth, along with a Social Security Number, even old-timers might forget
that modern manufacturing techniques for mass production that we take for granted
were pioneered long ago by people like Henry Ford. Not only did Mr. Ford conceive
of and implement a high efficiency assembly line for his horseless carriages, but
he also made a crucial decision that allowed his idea to work - he paid his employees
far above the prevailing wage of the era. $5 per day (worth about $112 in 2011)
was just the incentive Ford assembly line workers needed to keep up the fast paced,
repetitive work (workers got to keep almost all of their pay, because there were
no union dues, and Federal tax rate in 1913 was a whopping 1%). This video documents
the assembly line from <more>
4/17/2011
 "Here is radio, performing swiftly and efficiently
in the heat of battle," so says the narrator of RCA's promotional WWII film entitled
"Radio at War." It follows brothers
Joe and Jim Brown from their bedroom Ham radio set in Middletown, USA, to radio
school with the Army Signal Corps and the Navy Communications Dept., respectively,
and on into the field and onboard ship where they handle voice and Morse code operations.
Jim is elated as he sews on his Radioman 3rd Class "crow" patch after graduating from
communications school. Brother Joe departs for the battlefields of Europe as a sergeant
earning "$98 per month" after his training (I earned $419/mo. as an A1C radar tech
in 1979). He raves in a letter to home about the new walkie talkies that have a
range up to 5 miles that will surely "play an important part after the war." Wireless
communications was still in its infancy, where families gathered in front of the
tube radio for news and entertainment - "The magic of radio bridging space faster
than the most powerful plane." <more>
3/15/2011
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This archive links to the many video and audio
files that have been featured on RF Cafe.