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:
These images have been chosen for their uniqueness. Subject matter ranges from historic events, to really cool phenomena in science and engineering, to relevant place, to ingenious contraptions, to interesting products (which now has its own dedicated Featured Product category).
Cool Pic Archive Pages
looks like something from a video game, and in fact, I thought the story was a hoax at first; Photoshopped images
are rampant on the Internet. I even verified its existence by doing a
Google satellite map on the area just to make sure. Yep, it's real. Here is a massive structure that is reportedly
a Tesla generator of some sort. One of the pictures on the AboveTopSecret.com website shows a sign on the gate of
the apparently abandoned site that, translated, reads, "Isled. the center of the high energies." There is no information
about what the structure was used for, but if you zoom out on the satellite image, you will see to the southeast
a round area defined that is about 250 meters in diameter - possibly an underground synchrotron laboratory? Ah,
I just found some
additional info on it - the footprint of a former giant dome (cupola) that covered an unknown structure. It
could have been my guess of a synchrotron, and/or, looking again at the satellite photo, there appears to be some
sort or antenna array.
This gives a whole new meaning to "e-book." Computer geek cum sculptor Steven Rodrig created these books out of electronics waste that includes printed circuit boards and components. Per his PCBCreations.com About page, "Steven's innovative sculpture, which he refers to as 'PCB Mixed Media, is created from recycling and restructuring circuit boards and electronics parts." "Part of my discovery has been to develop special tools and use other tools in an unconventional way in order to manipulate each circuit board to form something other than what was originally intended." A sea turtle, shoes, an arachnid with orange and black tantalum capacitors for legs, multiple books, a dragonfly and other insects, and a faux city model that included vacuum tubes atop buildings are among his creations. There's even a binary bra. I wonder if Steven uses only Pb-free solder in his works?
The RFID Journal website has a new interactive world map that displays RFID deployments. "The goal is to show how widespread RFID adoption has become, and to help you find information regarding deployments relevant to your own RFID applications." Just like with Google Maps, there is a form you can fill out to put your own company and/or deployment on the map. You can even have it link to a press release that your company has issued. Information about the specific location pops up when you hover your mouse over a spot. You can zoom in on a area by drawing a rectangle with the left mouse button. Conspicuously non-densely populated are Japan and the eastern/southeastern regions of China. It is hard to believe that RFID is not very widespread there. Maybe their RFID people don't visit the RFID Journal website as often as Americans, Europeans, and Indians.
has a huge collection of radios, including this one of the world's first consumer transistorized radio, the Regency
TR-1. Nearly 100,000 were sold in the first year at a price of $49.95 ($417.68 in
dollars). Available in five designer colors, it was introduced in 1954 in time for the Christmas season.
The TR-1 used four germanium transistors and a 22.5 volt battery. Texas Instruments and Industrial Development Engineering
Associates (I.D.E.A.) consorted to produce the radio. An earplug accessory was available for $7.50
($462.70 in 2011 dollars). Transistor.org
also has a nice resource for beginners in radio restoration and a few articles detailing the innards of restoration
projects. It's worth a couple minutes of your time.
Nick Risinger decided it was about time that somebody created a single image of the entire night sky. So, with the assistance of his retired father, he dedicated a full year to photographing and then stitching together data from 37,440 separate exposures. The pair covered 45,000 miles by air and 15,000 miles by land. Braving thin, bone-chilling mountain air and wild animals in the U.S. western states and the Northern Cape in South Africa proved in some ways to be the easy part. The overwhelming task of sorting and processing the images required the application of some pretty sophisticated software, and a huge learning curve. Says Nick, "I divided the sky into 624 uniformly spaced areas and entered their coordinates into the computer which gave me assurance that I was on target and would finish without any gaps. Each frame received a total of 60 exposures: 4 short, 4 medium, and 4 long shots for each camera which would help to reduce the amount of noise, overhead satellite trails and other unwanted artifacts." An array of six cameras, each with a unique filter, was mounted on an equatorial... <more>
Maybe you have seen the Engineer's Troubleshooting Flow Chart that has been posted here on RF Cafe for many years. It is a satirical take on how to deal with problems in a project, but also pokes fun at the overused flow chart format itself. If you didn't know better, you might think this featured flow chart was a spoof as well. All the trademarks of a ruse are present, including seemingly unnecessary complexity and keywords like "misguided," "ragers," and "trolls." The surest sign that something might be amiss is the name of a government agency at the top. However, this flow chart is actually real and, according to a number of website authors who have adopted the process for their own blogs, forums, et al, useful. USAF officials decided a couple years ago to finally embrace the Web rather than eschew it as nothing but a security risk, so they had this guideline created and implemented. I have to say that if there was one branch of the government likely get something right, it would be the USAF.
you imagine what it cost to manufacture this PCA? Based on the number of jumper wires and add-on circuit boards,
there is a good chance it is actually a prototype, but sometimes low-volume assemblies live out their life cycles
in this state. I remember back in the 1980s when I built PCAs for Mil-Spec equipment, we often spent more time doing
the patchwork mods than assembling the original circuits. The maze of wires, components, and auxiliary boards was
considered more efficient than designing a whole new board, particularly if it was a retrofit for an upgrade or
if it was a new design, space and time did not allow for a new layout. Paperwork for the modifications was highly
detailed. It must have cost a fortune to implement. Look closely at this particular PCA and you will see a vacuum
tube on a vertically oriented add-on board (just below center-right). If you magnify the area, it looks like a bug
because of the sharply bent black wires supporting it. The motherboard looks like it uses surface mount components,
so it cannot be more than about 30 years old, making the inclusion of a tube suspicious - likely a prop for the
benefit of the picture, but maybe even a nixie. Everything else looks legit.
Mr. Jurvetson has a huge collection of cool
Nick Veasey is an x-ray artist. Owner and qualified operator of a shielded bunker full of x-ray equipment, Nick's mission is to, "challenge [the] automatic way that we react to just physical appearance by highlighting the, often surprising, inner beauty." He means it quite literally, the inner beauty part. Using lead-lined floors and walls as backdrops, a huge variety of subjects have been selected for imaging, including television sets and cameras, a rose and an orchid, children's toys, farm animals (none harmed in the process, I assume), a host of nasty insects (all harmed, hopefully), cockles and mussels, boxer shorts (sans human) and a folded shirt, binoculars and vacuum tubes, a French horn, and a Slinky. Subjects have not been limited to those which could fit inside the studio, however. Macro images have been assembled from a collage of many separate images. Vick exposed a bus full of people, a small office building (including elevator), and the pièce de résistance, a jet airliner being serviced inside a hangar. The airplane took more than 500 images. I'm guessing the outdoor images required cooperation with the subjects, especially considering the x-ray exposures involved. Cobalt, iridium, and ionizing radiation can be scary stuff. You might want to check out his book, X-Rays: See Through the World Around You.
If you have ever seen a mapping of neural connections in the brain, then you will probably think that this mapping of worldwide Internet connections looks familiar. It should come as no surprise given how patterns in nature tend to repeat across a very wide range of subjects. According to the GENI project folks, "It may look like a galaxy, but is actually a map of the Internet, showing the hardware that serves as its 'skeleton' or infrastructure of the Internet. Colors indicate geographic location. Despite its obvious complexity, this map represents just a fraction of the whole network - the rest is simply impossible to accurately represent." Of course this and other visualizations of complex networks are products of how humans choose to present them. There might be an added dimension that totally changes the interpretation. Recall in Contact (yes, I know it's sci-fi) how the eccentric rich engineer dude assembled the "alien" message in 3-D and revealed plans to a worm hole machine.
week's Cool Pic is more accurately a Cool Screen Capture. RF Cafe website visitor Ray Gutierrez generously provided
a paper for publication a few years ago, and now has provided a follow-on article on the subject of intermod cancellation
in RF amplifiers. Says Ray, "This paper is a continuation work for the 'New High Efficiency Intermodulation Cancellation
Technique for Single Stage Amplifiers.' Published in January 2008 on RF Café’s Paper section. The paper describes
configurations for dual and multiple parallel amplifiers and uses the basic Reflect Forward technique for intermodulation
cancellation. Some new improvements were made to the RFAL technique to improve the efficiency and operation." Further,
"I had done much of the work for this new paper back then but got busy doing other things in my retirement time.
The other day I got back to it and figured it was a shame to throw it all out without publishing it so that others
may benefit. I do not know if anyone has used this technique in a real product. I did not renew the USA patent so
anyone is now free to use it." Ray's paper is presented here in HTML format, but at the bottom of the page is a
link to the PDF file is you need that.
As recently as 1960, computers like this UNIVAC were still the only option for high speed data processing. These compact models required a mere 25x50-foot, air conditioned room to cool their 5,600 vacuum tubes (your computer has about 107 transistors). NPR mentions in its story a 1955 Broadway play called The Desk Set, pitting a fictional computer very much like UNIVAC against the reference library staff of a major radio-television network, otherwise known as "the desk set." In the end, the giant computer crashes and a librarian saves the day – with a hairpin. Katharine Hepburn (the librarian) and Spencer Tracy starred. A short video shows Walter Cronkite talking about the UNIVAC going against pundit knowledge and correctly predicted the outcome of the 1952 and 1956 presidential elections. The result? UNIVAC declared, "I like Ike."
Niels Bohr Institute physicist Sasha Mehlhase designed and built this scale model of the Large Hadron Collider over a span of almost 35 hours, at a cost of 2000€ ($2589US). Money was provided by the high energy physics group at the university. His 1:50 scale model uses approximately 9,500 LEGO blocks and is about a meter long by a half meter wide. Mehlase has contacted the LEGO company about kitting the model, but it is doubtful that there would be enough interest, especially at the price required, to make the effort worth while. However, I am offering a full-scale model of the elusive Higgs Boson (aka the "god" particle), which may or may not actually exist, for a mere $100US. It comes in a special display case, but don't expect to actually see the theorized particle because of its diminutively small size and mass. Oh, and it might have decayed back into pure energy by the time you receive the model, but trust me, it was once there, so help me god.