RF Cafe Software
About RF Cafe
1996 - 2022
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."
Note: There have been other videos posted, but I often forget to link to them on this page. Please use the website Search box at the at the top of the page to look for something you don't see here since many of the videos I have featured are not on these archive pages. Thanks.
Bonanza: Look to the Stars - Albert Michelson Light Speed Measurement
Albert Michelson is a name known to anyone who has taken (and paid attention during) a course in physics for his being the first person to accurately measure the speed of light in air. Born in 1852 to Jewish parents in Poland, his family emigrated to America in 1855 initially settling in Virginia City, Nevada. That happens to be where the fictional TV family of the Cartwrights owned their sprawling Ponderosa ranch in the series Bonanza. Screenwriters for the show took a bit of historical liberty in depicting young Michelson as having attending primary school in ...
Empire of the Air: The Men Who Made Radio
Empire of the Air: The Men Who Made Radio is a quite interesting documentary about the struggle that Edwin H Armstrong - inventor of the superregenerative and superheterodyne circuits, and of wideband frequency modulation (FM) - had with Lee DeForest - inventor of the Audio amplifying tube - and David Sarnoff - CEO of Radio Corporation of America (RCA). Extensive legal battles ensued between Armstrong and DeForest over vacuum tube patents, and Sarnoff's transition from biggest cheerleader to biggest thwarter of Armstrong's efforts are epic. A huge amount of historical information and vintage film clips ...
Mjölnir's Secret: Microwave Oven Magnets - Who Knew?
The secret of Mjölnir, Thor's hammer, has finally been revealed. As it turns out, being found 'worthy' of lifting Mjölner requires having the right thumbprint. Well, at least inventor / maker Allen Pan's version of the hammer does. The July/August issue of Popular Science ran an article on Pan's cleverly converted toy Mjölnir wherein he buried four lead-acid batteries to power a scrounged microwave oven transformer for duty as an electromagnet. An Arduino Uno-driven sensor detects Pan's unique thumbprint and disables ...
Morse Code vs. Texting Contest on the Jay Leno's "The Tonight Show"
On the May 13, 2005 episode of The Tonight Show, Jay Leno held a speed contest between two Ham Radio operators using Morse code and two Millennials using their smartphones for texting (SMS). At least one member of the audience thought texting would win. Mr. Chip Margelli (K7JA) did the sending. He declares, "Let me assure you that we never saw that message before I flipped the blue card over. Each message, in rehearsal, was different. The character count was the same as the one during dress rehearsal ..."
FPV Drone Tour of the Russian Duga-1 OTH Radar Antenna
Radio controlled drones have gotten a bad name, mostly due to moronic operators that have no regard for other people's privacy or safety. I would like to be able to say those types are in the minority, but unfortunately they probably do make up the majority of drone owners. That is because unlike with R/C airplanes and helicopters that require at least a modicum of skill and common sense to fly successfully, even the cheapest drones incorporate stability systems that are so good even a caveman could fly one. At the opposite end of the drooling loser contingent of the drone pilot spectrum is the rapidly growing number of highly skilled pilots that advance not just ...
Explosive Charges Bring down 48 VOA Towers in North Carolina
This item appeared on the ARRL news website. It links to a video showing an engineered demolition of a shortwave antenna farm in North Carolina commissioned by the Voice of America (VOA) in 1963, during the Cold War. The video provides an aerial view of the entire line of towers collapsing as the precisely timed charges go off. The most impressive aspect is that explosives are detonated only on every other tower in such a way that the falling tower takes out the one next to it almost in a dominoes manner (see yellow circle). 25 pounds of explosives were used rather than possibly 50 if every tower's guy lines had been ...
Old vs. New Car Design - Video
Very recently while watching a 1960s era TV show I asked myself a question I've asked many times before: If one of those heavy, bulky vintage cars constructed of thick pressed sheet steel body components, full steel tube frames, and cast iron 8-cylinder engine blocks was to have a head-on collision with a modern car built with light-weight materials of composite construction and minimal structural bulk, which would be the victor? My gut reaction was to think that the result would be like a sledge hammer and a Coke can colliding; I'd rather be the sledge hammer. I know cars are engineered to sacrifice the car to preserve the passenger compartment by ...
"Marble Machine" by Wintergatan
Maybe you are one of the more than 11 million people who have already viewed this incredible "Marble Machine" video, by Swedish musician Martin Molin. Molin designed and built his wooden music machine using aircraft plywood, ball bearings, Lego blocks, pressure transducers, plastic tubing, lengths of wire, springs, and a host of other off-the-shelf components, none of which appear to have required custom metal machining. The huge wooden gears were designed on his computer, ut out on a band saw, and assembled with glue and screws. 2,000 metal marbles are the lifeblood of the instrument which, by function, must be classified as percussion. Even the integrated base guitar is ...
iPhone 6 Plus vs. Samsung
There is no denying Blendtec founder Tom Dickson has earned the title of überBlendermeister with his online "Will It Blend?" series of videos. Using his company's Total Blender, Tom has over the years inserted, among many other things, popular and often expensive high-tech devices, and then pressed the appropriate button on the machine to start the action. Since its beginning in 2007, "Will It Blend?" videos have documented in a combination of full speed and slow motion the pulverizing of iPhones, iPads, Galaxy phones, Windows phones, Kindles, laser pointers, wii remote controls, Xbox 360 Kinect, a hearing aid, a video camera, magnets, and even a cassette tape. In the most recent episode, Tom hosts a …
You might recall seeing the video of Boston Dynamics' "Big Dog" robot that is part of a DARPA project developing battlefield automatons capable of carrying heavy loads at a swift pace over rugged terrain. Their newest humaniod, called "Pet-Proto," is enough to give you nightmares. Add a few lowpass filters on the joint mechanics and this boy would look like it came straight out of the Transformers or Terminator movies. One big hurdle that has to be overcome is the power source. Big Dog has an internal combustion engine driving a hydraulic pump (electronics probably work on batteries), and this Pet-Proto dude has hydraulic lines from an external supply. The robots are capable of autonomous decision making and are guided and motivated by GPS, LIDAR, ground sensors, gyroscopes, and other super-sophisticated devices.
Crystals Go to War
Many thanks to Kevin, of Roanoke, VA, for sending me a link to this documentary video covering the entire production chain for radio crystals as filmed by Reeves Sound Laboratory, in New York, NY. It was produced during World War II so the methods used are not anywhere near what is common today. What is the same, fundamentally, is the ingenuity and hard work that goes into developing a new technology, and particularly the effort needed to move to high volume production. As with most of these vintage factory films, a few aspects of normal practices of the era are immediately apparent. First is the near utter lack of personal safety devices on machinery and accessories for workers. Fingers run perilously close to diamond-impregnated crystal dicing blades, unprotected hands and arms are submersed in oils and cleaning solutions, no ear protectors …
Videos of automated factory fabrication and assembly lines are awesome. Watching the robots sling metal panels around for presses using hundreds of thousands of pounds of pressure to stamp out body panels for the Tesla Model S electric car is an inspiring reminder of how ingenuous and capable our fellow homo sapiens can be in spite of politicians' best efforts to enslave an underclass voting bloc of slackers. Think of the amount of knowledge required to conceive of and execute the processes show in this video - metallurgy, robotics, software, production planning, material sourcing and handling, factory environment, structural analysis, safety, testing, budgeting, training, union demands, human concerns, massive governmental regulation, surface finishing, marketing, work flow, and a host of other issues. That doesn't even include the brainpower necessary to plan, design, test, and build all the electrical and electronics parts of the vehicle. Utterly amazing. It takes 3-5 days from beginning to end to build a Model S. Even back in the 'old days' when most of the labor was manual, film reels showing masses of humans working together to make a complex piece of machinery like a Ford Model T will bring a tear to the eye of any self-respecting tech aficionado.
Turn Your Smartphone into a 3D Hologram
How does anyone even think of this stuff? This video demonstrating how to turn your smartphone into a holographic projector was posted by Mrwhosetheboss on August 1, 2015 and has over 10 million views already - and it's no wonder. He doesn't mention on the video what inspired the idea. A clear plastic CD jewel case cover it used to make the projection surface and specially created videos that project onto the four faces are used to create the holographic effect. The concept reminds of a little multi-faceted mirrored device that used to be sold which sat in the middle of a record player and turned flip-book ...
OK Go - "I Won't Let You Down"
OK Go is
perhaps best known for sophisticated videos that require extremely high levels of choreography. Their
I Won't Let You Down video
was posted on YouTube just yesterday and it has nearly 2.5 million views a day later. Back in 2010 I
posted their Mousetrap-like
This Too Shall Pass video; it now has more than 45 million views. Two major aspects of high
technology are featured here: Honda's UNI-CUB β robotic unicycle and the use of a remote control
drone for filming the video. Honda is not selling the UNI-CUB β yet, so Honda must have been
involved in the effort; the OK Go video is featured on the