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 ...
All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.
My Hobby Website:
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."
era of Smart Meters is upon us. Some welcome the technology, some eschew it, others loathe it, some
fear it. As with most new technology, the concept is utterly impressive. Smart Meters have the potential
to significantly improve power delivery system performance and reduce operational costs. Low power factors,
undersized cables, outdated equipment, and outright waste are among the problems plaguing our current
system. One solution is to build more generation capacity, but that is horrendously expensive. It makes
sense to remedy inefficiencies in existing installations before -or concurrent with - adding capacity.
Smarts Meters will play an important role in the process, but the problem is that there is great potential
for nefarious use of the information gathered on private homes and delivered to central offices. You
might know that according to law, once you grant a policeman or social service worker into your home
(w/o a warrant), you have implicitly granted unbridled access to your entire home. The same goes for
Smart Meter installations. Implied Consent is the operative phrase. Do you want Big Bro to surveil your
home to decide whether you are using only your "fair share" of electricity, and at the proper time of
day? Penalties might ensue. A guy who looks like Warren Buffet discusses the issue in this
video. Yes, I sent the letter to PenElec.
On June 15th, one of the longest lunar eclipses possible will occur - 100 minutes long, just 7 minutes shy of max length. That happens when the Earth is farthest from the sun (aphelion) so its apparent size is smallest - making the umbral cone longer - and when the moon transits the ecliptic in the middle of the earth's shadow. This NASA video explains the mechanics of an eclipse, including the redish color. Totality occurs at 20:14 UT, which is daytime in the U.S. All is not lost, however, if you live where the sun is just setting. At eclipse, the sun and moon are 180° apart in the sky. As you have probably noticed, the moon is clearly visible in the daytime sky, so plan to look near the eastern horizon at that time to see if you can spot the eclipsed full moon. Any set of binoculars or even the naked eye should provide a good view. This PDF file maps the times and phases. Here are the pics I got of the February 20-21, 2008 lunar eclipse.
Crows are very intelligent birds. According to researchers, they are capable of recognizing individual humans and can tell which ones have posed a threat in the past and which have not. Crows are known to fashion simple tools from wire and sticks to probe for food, and to make a variety of sounds for communicating with other crows. Their eyesight is quite keen, almost eagle-like. Crow brains are about the same in size relative to their bodies as the great apes, so a higher level of intelligence is not surprising. They are of the genus Corvus, renowned in literature for being wily and alert. But, that is not the kind of crow this article is about. This kind of crow is a U.S. Navy radioman that engages in electronic warfare. According to the Association of Old Crows (AOC) website, "During World War II, Allied ECM officers, tasked to disrupt enemy communications and radars, were given the code name of 'Raven' to provide a degree of security to their existence. After WWII, a group of Raven operators were directed <more>
Reuters recently published a story about how Berlin is becoming Europe's new technology hub because of the wave of start-ups being created by young entrepreneurs. According to Mike Butcher, editor of TechCrunch Europe: "A very international scene, a lot of people speak English, it has a big arts scene which attracts a lot of internationals. Economically pretty affordable, so if you're developing a new technology start-up and you don't have any pre-existing revenues, then that's a great advantage. What's going to happen is that the start-ups which are getting visibility tend to have more of an international footprint and therefore attract the interest of the Silicon Valley venture capital community." It seems Germany is a standout amongst EU states from an economic health perspective, and of course Germans have long been recognized as leaders in technological innovations. Einigkeit und Recht und Freiheit.
Every cause needs its cheerleaders to appeal to the uninitiated masses. Believe it or not, the combined fields of science, mathematics and engineering has its own cheerleader squad - literally. The ScienceCheerleader.com website is a cornucopia of information on women who were once cheerleaders for professional sports teams and have moved on to careers in the sciences. Some are now aerospace engineers, some are school teachers teaching mathematics or science, while others work in various and sundry science fields. In their mission mission to rescue smart women from the shameful vocation of cheerleading and set them on their way to a respectable career that serves mankind*, the Science Cheerleaders made a short promotional video titled, "Brain Makeover: What Everyone Needs to Know to Be a Science Literate." Cheerleaders from the Buffalo Bills, the Baltimore Ravens, and Miami Dolphins are among the converts. The question I have is: Did these women have to take a pay cut when moving from professional cheerleading into the science fields? <more>
We are all familiar with standard round gears, worm gears, differential gears, and orbital gears - well, maybe not as many are familiar with orbitals. These videos demonstrate how the proper geometric relationship between meshing gear sets allows just about any shape to work. While a lot of the shapes shown are curiosity objects, there are reasons for using such devices. If you imagine a pushrod attached to the output gear, you will notice that for non-round gears, there is a non-linear relationship between the constant input rotation speed of the driven gear and the output gear. One fairly common, but not so familiar type gear is the Geneva mechanism. It is used where incremental movement at the output is required. The video below, and the animation shown to the left (click it) demonstrates how while the driven gear (green in the animation) rotates at a constant speed, the output gear (red) rotates only when the pin on the green gear engages it. During the rest of the green gear rotation, the red gear is prevented from rotating by the semicircular portion of the green <more>
"Can you hear me now?"
is a trademark question brilliantly conceived of by Verizon and repeated ad nauseam by its geeky repair
guy in TV commercials. 30 years earlier, NASA outdid them big-time. On July 20, 1969, the as yet unbroken
long distance phone call record was set by President Nixon from the Oval Office. Per the
daily diary, "The President held an interplanetary conversation with Apollo 11 Astronauts, Neil
Armstrong and Edwin Aldrin on the Moon." Get that? Interplanetary!
I am not sure where the moon was in relation to the Oval Office, but the distance could have been anywhere
from about 226 kmiles to 257 kmiles. If you listen closely, you can hear the 2.5-second echo caused
by the round-trip radio signal propagation time (note "to join" at 1:18, then
echo at 1:20). Do not be tempted, as some commenters on the video did, to claim the Moon call
does not count because a radio was required between the desk phone and Eagle
(re-designated Tranquility Base while on the surface); that is
how your cellphone works. <more>
Before we allow analog design guru Bob Pease to finally rest in peace, it is essential that you view this video of his office at National Semiconductor. Bob's outrageously messy office has been the topic of many conversations over the years. The organizationally challenged amongst us point to Bob's office as proof that being a slob does not automatically mean that you are generally unskilled and never owned a bar of soap. In fact, many fellow engineers have testified to Bob's ability to find anything in the pile in short order when necessary - no matter how long ago the catalog, datasheet, purchase order, or lab notebook might have been added. That Bob was a genius on many levels is utterly beyond challenge. Somehow, though, I do not imagine Marilyn Vos Savant's office exhibiting a similar degree of chaos, so being messy is certainly not requisite to being a genius. Be amazed while watching this ad hoc filming of Bob's office by compatriot Paul Rako just a couple short years ago.
Most of the time if I have a small electronics project to build or if I need a new set of voltmeter probes, I'll place an order with Digi-Key or Newark Electronics. There are times when I need something right away and don't want to pay for overnight shipping, so I'll go online to Radio Shack to see if they have what I need. All too often the part needed is not stocked in the local store even though it is available online, so that does not solve the problem. I have mentioned - alright, complained - to the salesmen about losing potential business because they no longer stock very much in the stores; 30 years ago the stores had much more on-hand. Back in my USAF days, I once built an entire 30 W stereo amplifier off of a schematic with parts purchased at a Radio Shack store - even the transformers and metal chassis. I probably could not do that today. To their credit, Radio Shack has recently launched a program that solicits input from you for suggestions as to what should be added to the shelves (and online, I suppose). So, this is your chance to influence a major corporation's policy.
5/31/2011Half a century ago, radar was still a mystery to most people. Radio in general was still a mystery for that matter. For that matter, radio and radar are still mysteries to most people, it is just that today the devices are ubiquitous - even if the people do not realize what miracles of engineering they are. Radar played a crucial role in pushing back Axis forces during World War II. Not only did it afford advanced notice and estimation of air force sizes many miles in advance of their approaches, but it also warned of land an sea forces. Surprise attacks above or within fog and rain were no longer tactics that could be assumed to be successful. In trademark form from the WWII era, this newsreel titled "Radar Secrets Revealed" presents a high level demonstration of how the early radars functioned, complete with trademark music and enthusiastic, deep-voiced narration. I almost felt an obligation to stand at attention while <more>
RF Cafe visitor Victor T. sent me a link to this video produced by NXT to demonstrate the ruggedness of their LDMOS power transistor. Per NXP: "Tired of replacing tired, dead power transistors? Check out NXP's Unbreakable BLF578XR LDMOS RF Power Transistor in this video - and find out just how rugged eXtremely Rugged is! Would you dare to treat your transistor like this?" The transistor is shown surviving arcing, short circuits, open circuits, and extreme VSWR values. Having personally blown power transistors on the bench because of forgetting to hook up the load, I can appreciate the idiot-proofness of such a device. Of course the purpose of the design is mostly to facilitate survival in the field where transmission line damage or improper installation might otherwise destroy the device. One thing I noticed about the video is that none of the technicians/engineers doing the testing wore ESD protection straps. Maybe they had good mats and shoes, but I don't think so.
Every engineer wants a patent. Go ahead, admit it. I would like to own a patent, but probably never will unless I buy the rights to one... but even that would technically only make me an assignee, not an inventor. Some people are prolific inventors and patent awardees. If you work for a large company, you probably know one of those Thomas Edison types. Others have equally good ideas but either lack the opportunity to develop the notion into patentable form, lack the knowledge of how to initiate a patent, or both. A key part of the effort is determining whether or not your invention is even patentable. Fortunately, intellectual property attorney Eric Hanscom, of law firm InterContinental IP (ICIP), has created a series of short videos that explain various aspects of patent application process. Topics like "What is Intellectual Property: An Introduction," "Design Patents: The Basics," "Is My Invention Patentable?," "Utility Patents vs. Design Patents," and "Need A Patent Quickly? Learn About Accelerated Examination" are among more than two dozen videos that run 2 to 3 minutes each. <more>