1996 - 2016
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...
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This collection of video and a few audio files represents files that have been featured on the RF Cafe homepage. Every week or so a new file is added that should be of interest to RF Cafe visitors.
Please send me an e-mail if you have a good subject. Note: "Videos for Engineers" formerly went by the name "Cool Videos."
than the perpetually self-employed and the perpetually unemployed (aka bums), most people have been
to at least one job interview. Even after multiple interviews over many years, I was always nervous
- mainly because I really wanted the particular job being advertised - so messing up wasn't an acceptable
option. Because the companies I chose to apply with were all highly respected, there were never any
instances of the interviewers being idiots or hostile. I've been lucky. A lot of people have not been
so fortunate. One person that called recently told of being asked about how he'd approach solving a
certain problem, and then the interviewer called him back again a few days later to get additional detail
about his idea for troubleshooting, ostensibly to gain more insight into his abilities. It turns out
that he thinks he solved a problem for them, and that the company was just exploiting interviewees to
get free consulting. That's the stuff of Dilbert comic strips, which, unfortunately, are largely based
on stories that Scott Adams gets from people's real-life experiences. Here is a classic Monty Python
video of an interview from Heck. <more>
Being a teacher in public schools is a demanding job, so they tell us. The students have no self-discipline, and the school rules prevent the teachers from taking effective action to control the classroom. Of course, their own representatives have brought it on them through politically correct mandates. My sister has been a teacher for 30 years, and boy have I heard some stories about moronic students and parents. The students' inconsiderate behavior of course is carried over into the college classroom. There, though, especially at private universities like Cornell, the rudeness is likely to be quashed by a professor. This video shows that exact scenario when someone blurts out a very loud yawn during class. I side with the prof.
Budding teenage scientist Eric Jacqmain has created a YouTube sensation with his "Solar Death Ray." Per Eric, "The R5800 is my latest and greatest solar creation. Made from an ordinary fiberglass satellite dish, it is covered in about 5800 3/8" (~1cm) mirror tiles. When properly aligned, it can generate a spot the size of a dime with an intensity of 5000 suns! This amount of power is more than enough to melt steel, vaporize aluminum, boil conc
rete, turn dirt into lava, and obliterate any organic material in an instant. It stands at 5'9" and is 42" across." The performance is pretty amazing, especially given its low-tech approach. It would be interesting to know whether Mr. Jacqmain has sustained any flesh burns while holding objects in the focal point. I would not be holding anything in my fingers while searching for the hot spot. Ironically, the shed used for storing the R5800 burned down; maybe it was facing a window with a southern view?
If you are one of those outdoor types who loves to explore dangerous environments, watch closely. This video shows what can happen when a crocodile decides to eat an electric eel for dinner. It is an amazing, albeit gory, sight to behold. In a more urbane demonstration of the electric eel's potential (pun intended), an aquarium in Japan lights a Christmas tree with the charge supplied, compliments of the beast in a tank. The electric eel is actually not an eel, but a knifefish. It breathes air at the surface, then dives for 10 minute periods. It can generate up to 500 volts at 1 amp (500 watts), delivered at 10 Hz up to a few hundred Hz. Recall that it only takes 1/10 amp to kill a man. At 500 V, a body resistance of less than 5 kΩ spells doom.
RFID, near-field communications (NFC), magnetic strips, movement-tracking radars in grocery and department stores, all are systems designed to facilitate efficient merchandizing. Even when used legally, many aspects of the science are cause for concern from a privacy perspective. Visions of Orwell's Big Brother immediately come to mind, where an overarching, omnipresent government monitors and controls the movement of society's pawns... er, citizens. Distributors and users of the sensor products (RFID, NFC tags) and tracking systems range in complicity from useful idiots (sorry, but that's a well-defined term from the Stalinist crowd) to prosecutable criminals. The overwhelming majority (including myself) are part of the former. Marketing firms, government entities, and street vermin make up the <more>
The self-proclaimed wizards of smart in the lamestream news media
have once again been exposed. Off-air gaffes and brazen displays of bias are de rigueur with these idiots
who pretend to be intellectual, objective, and neutral while on air. When they think the cameras and
microphones are off, caution is tossed to the wind, the outer skin is shed, and the true nature comes
out. Here we see a pre-show segment of NBC's Today show where clueless Katie Colic and Bryant
Gumball wondering what is this newfangled thing called the Internet,...
Oh, in the spirit of NBC's philosophy of tolerance and bringing the results of investigative reporting to the world, as it ostensibly does with shows like Dateline, it summarily fired the guy who leaked this video. The hypocrisy of the elite continues to amaze. <more>
Jon Stewart has a great satire on Verizon's announcement for adding the iPhone to its repertoire. In his trademark wry presentation style, Stewart treats us to the riveting public event where Verizon CEO Lowell Mcadam stirs the audience to a level of passion not witnessed since ClingFree™ dryer sheets hit the market. Street reporter John Oliver gets heart-wrenching stories from AT&T iPhone users whose live have been destroyed by the near criminally substandard service. Rituals reminiscent of the proletariat's toppling of Saddam Hussein's statue in Iraq are filmed in the joyous announcement by Verizon. You'll want to watch it.
In the spirit of the season, I have made a tradition of posting a few of my favorite online Christmas music videos. Here is an eclectic mix of "Christmas Eve in Sarajevo" and Pachelbel's "Canon in D," by Trans-Siberian Orchestra. This "Carol of the Drum," (aka "Little Drummer Boy") duet by by Bing Crosby and David Bowie is an amazing blend of the old and the new.
from RF Cafe!
12/21/2010We read a lot about the early radar system that was in operation at Pearl Harbor in December 1941 when the surprise attack by Japanese naval airplanes decimated the fleet with a 3-hour-long raid beginning at around 8:00 on that sleepy Sunday morning. The SCR-270B (Signal Corps radio #270, rev B) radar system had a range of 250 miles at an altitude of 50,000 feet. Westinghouse built the system in 1940 following a development contract issued by the Army Signal Corps in 1936. Radar's roots goes back to the late 19th century when Heinrich Hertz conducting experiments of radio signals being reflected off metal surfaces. In 1904, German scientist Christian Hülsmeyer gave a demonstration of his "telemobiloskop." By the early 1930s, the U.S., Great Britain, Germany, the USSR, Japan, the Netherlands, France, and Italy, were all working on radar development programs. <more>
It seems like every year we see videos posted of icicles falling from television station transmission towers, crashing into vehicles in the parking lot. This one from WJTV News Channel 12, in Jackson, Mississippi, stands out because it shows people actually running toward their cars while the icicles are falling from a 491-meter high tower. They apparently are so concerned about damage to their vehicles that they discount the potential for mortal harm if one of those gigantic icicles happened to hit them. You can hear the people laughing as they run into harm's way. One day we'll see one of them in the annual list of Darwin Award winners. Sad, but true.
LEGO® and tinkerers of all ages have enjoy a long, synergistic relationship that has led to incredible creations of mechanical contraptions and artistic sculptures. I have reported previously on LEGO re-creations of the Babbage Difference Engine, a fully-functional Fender guitar, and even full-size human replicas (do a search on LEGO images). Now, an Apple engineer has re-created the long-lost and recently-found Greek Antikythera Mechanism. 1,500 LEGO blocks and 110 gears were combined over a 30-day period of designing, building, and testing to produce this mechanical wonder. Maybe Apple should assign this guy to design the iPod 5 antenna - or at least the long-awaited iPod 4 white case!