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Today in Science History

Mathematical Puzzles, 1985 OFA

Mathematical Puzzles, 1985 Old Farmer's Almanac - RF CafeHere is another set of "Old and New Mathematical Puzzles," compliments of the 1985 edition of the Old Farmer's Almanac. All of the puzzles from Difficulty 1 through Difficulty 3 can be worked out without much trouble. Puzzle number 3 is a variation on an optical illusion based on the Möbius strip, or maybe more like a Klein bottle. Of course, being a farmer thing, there's a puzzle involving the number and price of produce at the market. There are four Difficulty 5 puzzles for which no solutions are given. They are the ones where readers are invited to submit solutions, and the winner for each receives a $50 award and honorable mention in the next year's edition. The winning solutions are never shown, but you can write to request a copy of them. It would be interesting to see what the solutions look like for this year's puzzle 13. You need to be good at three-dimensional drawing to render them...

Comic with an Electronics Theme

Comic with an Electronics Theme, June 1972 Popular Electronics - RF CafeClose out this day with a tech-themed comic from a 1972 issue of Popular Electronics magazine (only one this time). Those of you who entered the engineering realm sometime after the 1990s might not recognize the strange looking surface the guy is sitting behind. It was an early tabletop touch-type display where the stylus with which the user created an image (drawing) was a wooden stick with a round shaft of graphite located coaxially in the center. The pointed, relatively soft tip wore down rather quickly and required frequent reshaping to maintain a constant pixel width in the lines. Portions of drawings made on those devices could only be erased and redrawn a few times as with modern solid-state drives. Cutting and pasting required physical cutting and pasting (or taping). Clipboards were often used to hold frequently replicated snippets of renderings (title blocks, standard drawing notes, etc.) for pasting into a drawing. One big drawback of those older drawing programs was that after a day's work you usually went home with a layer of graphite on your palm and shirtsleeve...

Silicon Electro-Optical IC Narrowband Multi-GHz Filtering

Silicon Electro-Optical IC Narrowband Multi-GHz Filtering - RF Cafe"It's a very safe bet that a wireless or wired system uses at least one filter - and likely many more - in their various forms: low-pass, high-pass, notch, or bandpass. As operating frequencies increase into the gigahertz and tens of gigahertz range, it's increasingly difficult to create filters with narrow bandpass or notch performance, especially using discrete-device versions which are almost always impractical in that range. While there are ways to create such filters using surface-acoustic-wave (SAW) and bulk-acoustic-wave (BAW) technologies, even these technologies struggle to keep up with the demands for narrow bandwidth filtering at these ever-higher frequencies. Recognizing the need and opportunity, the photonic and electro-optical (E-O) community is doing a great deal of research to overcome these barriers. For example, researchers at the University of Sydney (Australia) Nano Institute devised a compact semiconductor chip that provides for the heterogeneous integration of chalcogenide glass with silicon to create specialty filters. Their effort has resulted in a notch filter with narrow 37-MHz 3-dB bandwidth..."

RF Energy Powers Incandescent Lamp

R.F. Energy Powers Incandescent Lamp, April 1956 Popular Electronics - RF CafeWireless power distribution has been in the news a lot for the last few years. It began with a goal of just wirelessly charging mobile devices like cellphones, smart watches, and tablet computers. Next came articles about charging electric cars wirelessly while sitting in a parking lot or garage, or even at a stop light. In each instance, the item being charged needed to sit in close proximity to an electric induction coil to be effective. Just a couple days ago, however, a new item appeared where Disney Research has come up with a "quasistatic cavity resonance" system that covers an entire room. This story from a 1956 edition of Popular Electronics magazine reports on an incandescent lamp powered wirelessly by an RF energy source. It's not quite the same thing, but is the same basic principle...

RF & Electronics Stencils for Visio

RF & Electronics stencils for Visio r4 - RF CafeWith more than 1000 custom-built stencils, this has got to be the most comprehensive set of Visio Stencils available for RF, analog, and digital system and schematic drawings! Every stencil symbol has been built to fit proportionally on the included A-, B-, and C-size drawing page templates (or use your own page if preferred). Components are provided for system block diagrams, conceptual drawings, schematics, test equipment, racks, and more. Page templates are provided with a preset scale (changeable) for a good presentation that can incorporate all provided symbols...

More Meters for Beginners

More Meters for Beginners, December 1964 Radio-Electronics - RF CafePrior to the advent of meters with a super high input impedance (>1 MΩ) featuring field effect transistors (FETs), accurate use of a voltmeter or ohmmeter required knowledge of the meter's internal resistance and the resistance of the device under test (DUT). As can be seen in Figure 2, various range settings on the meter resulted in different internal resistances. The internal resistance of the meter in series with the resistance of the DUT form a voltage divider where the indicated voltage is less than that which would be indicated if the meter's internal resistance was much higher. Author Robert Middleton presents examples of possible errors when measuring voltage, current, and resistance. Many modern digital multimeters (DMMs) have an input impedance of at least 10 MΩ, so very few scenarios would require minding the meter characteristics. With DMMs there is also no need to learn how to interpret the multiple needle scale markings, or to take care to avoid parallax error as a result of not looking at the needle from directly perpendicular to the scale markings, or keeping track of the reading units (mV, V, mA, A, Ω, kΩ, MΩ...

Transistor Topics

Transistor Topics, January 1956 Popular Electronics - RF CafePopular Electronics magazine ran their "Transistor Topics" column for many years, and this is the third in the series. Unfortunately, I do not yet have the previous two editions, but someday... Transistors were a relatively new phenomenon at the beginning of 1956, so there was a lot to learn and a lot of people to teach about them. It might have been easier to make converts of dedicated tube users if the JFET (junction field effect transistor) had been commercialized before the BJT (bipolar junction transistor), since the JFET (voltage on the gate controls current flow) acts more like the familiar vacuum tube (voltage on the control grid controls current flow) than the BJT (current on the base controls current flow)...

Integrated Satellite with Mobile Devices

Integrated Satellite with Mobile Devices - RF Cafe"The formation of the Mobile Satellite Services Association (MSSA) marks a significant stride towards enhancing global connectivity through the emerging Direct-to-Device (D2D) and Internet of Things (IoT) services. Leading entities in the satellite communications sector, including Viasat, Inc., Terrestar Solutions, Ligado Networks, Omnispace, and Al Yah Satellite Communications Company PJSC (Yahsat), have come together to establish this non-profit industry consortium. The MSSA's mission is to harness over 100 MHz of L- and S-band spectrum-already allocated and licensed for mobile satellite services (MSS)-to build a robust global ecosystem that integrates seamlessly into a wide array of mobile devices. The Association's alignment with 3rd Generation Partnership Project (3GPP) standards is a critical move to broaden terrestrial mobile coverage, including for Mobile Network Operator (MNO) and Over-the-Top (OTT) internet services. This strategic initiative underscores the inherent advantages of MSS licensed spectrum, such as the capability for existing space networks to instantly provide Narrowband Internet of Things (NB-IoT) services..."

Electronics Crossword Puzzle

Electronics Crossword Puzzle, March 1973 Popular Electronics - RF CafeRegular RF Cafe visitors know I have a penchant for creating and solving crossword puzzles. Since around 2001, I have personally generated a new crossword almost every week - hundreds in total. Some studies have suggested lower rates of dementia in people who regularly exercise their brains, but that is not the primary reason I work crossword, word scramble, and Sudoku puzzles - I enjoy the challenge. A couple times each year, Popular Electronics magazine published an electronics-themed crossword puzzle; however, unlike the crosswords I make, not all of the words and clues have to do with technology and science. Still, they're a good pastime activity...

Promote Your Company on RF Cafe

Sponsor RF Cafe for as Little as $40 per Month - RF CafeBanner Ads are rotated in all locations on the page! RF Cafe typically receives 8,000-15,000 visits each weekday. RF Cafe is a favorite of engineers, technicians, hobbyists, and students all over the world. With more than 17,000 pages in the Google search index, RF Cafe returns in favorable positions on many types of key searches, both for text and images. Your Banner Ads are displayed on average 280,000 times per year! New content is added on a daily basis, which keeps the major search engines interested enough to spider it multiple times each day. Items added on the homepage often can be found in a Google search within a few hours of being posted. If you need your company news to be seen, RF Cafe is the place to be...

Westinghouse Radio

Westinghouse Radio, August 13, 1945 Life - RF CafeWestinghouse, headquartered in and around Pittsburgh, Pennsylvania, was a major force in all aspects of commercial broadcast radio. The company designed, manufactured, installed, and managed broadcast studios and transmission equipment. They also made some of the greatest complexity and quality receivers. Many were truly masterpieces that complimented rooms outfitted with high end furniture. Other companies like Crosley also made very large, multi-featured consoles with record-changing phonographs, AM and shortwave receiver bands with pushbutton tuning, AGC and AFC circuits, ample storage space for records, built-in antennas, AC or DC operation, and other bells and whistles. Curvaceous solid and plywood construction was solid and finishes had a deep luster. This full-page 1945 Life magazine advertisement was a pitch for what would have been one of the first new radios sold at the end of World War II, during which all resources had been dedicated to military equipment thanks to the War Powers Act of 1941. Although not mentioned, I'm guessing the girl is the daughter of either John Charles Tomas or Ted Malone...

Plasma Stealth Device Takes Aircraft off the Radar

Plasma Stealth Device Takes Aircraft off the Radar - RF Cafe"A new-generation plasma stealth device that can make almost any military aircraft vanish from a radar screen is claimed to have been developed by a team of scientists and engineers from western China. Unlike its predecessors, which generate a cloud of plasma draped over a plane, this innovation can be tailored to fit a sensitive section of a military aircraft - areas like the radar dome, cockpit or other spots that are most prone to enemy radar detection. This 'closed electron beam plasma stealth device,' which focuses on protecting key areas instead of the entire aircraft, can be switched on at a moment's notice to fool radar operators. It has many advantages such as 'simple structure, wide power adjustable range and high plasma density,' Tan Chang, a scientist involved in the project, wrote in a peer-reviewed paper published in the Chinese Journal of Radio Science in December. Chinese scientists say they can use foreign military radar to track ships. Plasma, composed of electrically charged particles, interacts with electromagnetic waves in a unique way. When electromagnetic waves - such as those emitted by radar - interact with plasma, they cause the particles to move rapidly and collide, dissipating the waves' energy and reducing the strength of the reflected signal. This interaction converts the energy... (line 546 in page source view for non-subscribers)

Transistor Selection Guide for Experimenters

Transistor Selection Guide for Experimenters, June 1974 Popular Electronics - RF CafeBelieve it or not, there are still people out there - engineers and hobbyists - who design circuits using discrete transistors. Sure, there is a plethora of integrated circuits that combine multiple functions into a single package that performs often nearly like ideal components, and for a lot less money than building an equivalent circuit from individual components. Still, sometimes a lone transistor with a couple biasing resistors will do the job, and sometimes the designer just wants to do something different. There are also plenty of instances where you need to find a replacement of a failed transistor that has similar form, fit, and function. This article from a 1974 issue of Popular Electronics magazine might be just the aid you need if you have found yourself in need of selecting a transistor. Of course if your application is for high frequency, there are parameters to consider other than those presented here, but it's a good start...

Home-Brew Double Balanced Mixer

Home-Brew Double Balanced Mixer - RF CafeDouble-Balanced Mixer Schemtatic - RF CafeWhen RF Cafe visitor Ed W. saw the photo I posted of the très cool looking miniature isolation transformers from "Exploring Uncommon Applications of Isolation" it reminded him of a double balanced mixer his company designed back in the 1970s for a line of high frequency (HF) radios like the Cubic Astro 200. At the time, it was considered more economical than a commercially made mixer. Unless exceptionally high power handling is required, a modern integrated double balanced mixer like this one from Marki Microwave will have better higher performance because the diodes will all be nearly perfectly matched. The same is true, of course, for triple balanced mixers. Double balanced mixers tend to suppress odd order spur products to a greater degree than even order products, while triple balanced mixers tend to suppress even order spur products to a greater degree than odd order products.

Sylvania General Telephone and Electronics

Sylvania General Telephone and Electronics Ad, February 1970 Popular Electronics - RF CafeIn 1970, Sylvania ran this 2-page advertisement in Popular Electronics magazine touting the accomplishment of reducing the equivalent of 60,000 discrete components to a mere 60 - thanks to integrated circuits. That 1,000:1 ratio is miniscule compared to this year (2017) where AMD's 24-core EPYC 7401P sports 19,200,000,000 transistors. If Moore's Law continues, we can expect nearly 40 billion in another year and a half. Sylvania was not claiming to be able to replace all components with integrated circuits, just to drastically reduce the number of parts needed to stock for prototyping and production. Even AMD's gigaprocessor needs a large handful of capacitors sprinkled around its periphery to function in the presence of electrical noise and power fluctuations, and also a few steering diodes and pull-up resistors. I don't dare make a statement like, "There will always be a need for discrete passive components," because bioelectronics might easily replace both discrete and integrated components with gelatinous blobs of synapse-filled gray matter, powered by pseudo stomachs fed by frankenpellets of nutrition...

RF Cascade Workbook

RF Cascade Workbook - RF Cafe RF Cascade Workbook is the next phase in the evolution of RF Cafe's long-running series, RF Cascade Workbook. Chances are you have never used a spreadsheet quite like this (click here for screen capture). It is a full-featured RF system cascade parameter and frequency planner that includes filters and mixers for a mere $45. Built in MS Excel, using RF Cascade Workbook is a cinch and the format is entirely customizable. It is significantly easier and faster than using a multi-thousand dollar simulator when a high level system analysis is all that is needed...

News Briefs: Telephone Switching Networks & Fluid Amplifiers

News Briefs: Telephone Switching Networks & Fluid Amplifiers, December 1964 Radio-Electronics - RF Cafe"Semipermanent" magnetic memory is reported here in this 1964 Radio−Electronics magazine news item. The term semipermanent is an awfully good, clearly confusing, but seriously funny example of an oxymoron, akin to jumbo shrimp, old news, random order, and unbiased opinion. An electronic switching system is announced which will replace the massive network of electromechanical switches in the nation's telephone system. Once implemented, the cacophony of clicking relays heard inside the switch rooms containing thousands of of the noisy little buggers would go silent. I remember being in such a facility in the mid-to-late 1970s where the electromechanical relays were still being used, so it was well over a decade before a total switchover (see what I did there?) was completed. Also covered was a computer built by Univac that used fluid amplifiers (literally a fluid, including air). Also, there was news of the "World's Greatest Amateur," John L. Reinartz, W1XAM, having attained Silent Key status...

New Radio Rucksack for U.S. Army

New Radio Rucksack for U.S. Army - RF Cafe"The Army is testing a new rucksack that was purpose-built for radio operators to reduce damage to systems on drops, add space, improve fit and cut down on heat. The Radio Carrier Rucksack was assessed in airborne drops with soldiers at Yuma Proving Ground, Arizona, according to an Army release. The radio ruck is being developed by Natick Soldier Systems Center under the Army's Combat Capabilities Development Command. Soldiers evaluated the ruck with both the AN/PRC-158 and AN/PRC-162 radios in 'combat-realistic scenarios' to see whether the new setup could prevent damage to radios during parachute jumps. Developers have modified the existing Modular Lightweight Load-carrying Equipment assault pack that's fielded across the service. 'The radio harness allows the radio to be connected to the existing assault frame, while the side pouches allow for individualized space to store antennas away from other equipment and gear,' explained Bob Cohen, Manpack Lead Test Engineer..."

Why Use a Triac?

Why Use a Triac?, April 1974 Popular Electronics - RF CafeThe Triac (triode for alternating current) is not a component often used in RF and microwave circuit design, but being conversant in its operation could make you popular at nerd parties. A triac is basically the equivalent of two SCRs (silicon-controller rectifier, aka thyristor) connected back-to-back, allowing it to conduct on both the positive and negative half-cycles of an AC connection. Both devices are most commonly used in switching applications. The unique feature of an SCR and triac is that once the gate voltage is sufficiently high to begin conduction between the anode and cathode, it can be removed and conduction will continue until the anode-cathode voltage is removed (i.e., holding current removed). This 1974 Popular Electronics magazine article introduces and explains the operation and applications for triacs...

Sora Cinematic AI Generator

Sora Cinimatic AI Generator - RF CafeI, for one, do not fear the emergence of artificial intelligence (AI). The fact is we have been living through an evolutionary process in AI since the beginning of the computer age - it just wasn't called AI at the time. Electronic and mechanical CAD/CAE software with optimization routines are AI. PCB layout autorouting is AI. Weather prediction algorithms are AI. MRI and x-ray images processing is AI, as is tax preparation software. I'd say "get used to it," but you already have. This Sora project by OpenAI (the ChatGPT folks) is basically a real-life rendition version of what Pixar is for cartoon animation. "We're teaching AI to understand and simulate the physical world in motion, with the goal of training models that help people solve problems that require real-world interaction. Sora can generate videos up to a minute long while maintaining visual quality and adherence to the user's prompt. Sora is able to generate complex scenes with multiple characters, specific types of motion, and accurate details of the subject and background. The model understands not only what the user has asked for in the prompt, but also how those things exist in the physical world. The current model has weaknesses. For example, a person might take a bite out of a cookie, but afterward, the cookie may not have a bite mark..." The movie industry is crying foul, but honestly, would many people care if the egotistical, largely ignorant, bloviating Hollywood actors went away?

New Hologram Crystals Permanently Store Images

New Hologram Crystals Permanently Store Images, August 1972 Popular Electronics - RF CafeLithium niobate is used today as the substrate for surface acoustic wave (SAW) filters, oscillators, optical waveguides, and many other applications. It, along with barium niobate, was used experimentally by Radio Corporation of America (RCA) for storing optical images that can be read out later using a laser. This 1972 issue of Popular Electronics magazine included a brief news item referencing the work being done. I could not locate any information that indicates any significant commercialization of the process. Patent US3799642 was awarded in 1974 to RCA Corporation for "Holographic Recording on Photochromic Lithium Niobate." We've come a long way since then with optical data storage, with CDs, DVDs, Blu-rays, and much greater density into the petabit realm...

How to Target RFCafe.com for Your Google Ads

Google AdSense - it makes good sense - RF CafeOne aspect of advertising on the RF Cafe website I have not covered is using Google AdSense. The reason is that I never took the time to explore how - or even whether it is possible - to target a specific website for displaying your banner ads. A couple display opportunities have always been provided for Google Ads to display, but the vast majority of advertising on RF Cafe is done via private advertisers. That is, companies deal with me directly and I handle inserting their banner ads into the html page code that randomly selects and displays them. My advertising scheme is what the industry refers to as a "Tenancy Campaign," whereby a flat price per month is paid regardless of number of impressions or clicks. It is the simplest format and has seemed to work well for many companies. With nearly 4 million pageviews per year for RFCafe.com, the average impression rate per banner ad is about 280k per year (in eight locations on each page, with >17k pages)...

Bell Telephone Laboratories: Electrical Pipe-Line

Bell Telephone Laboratories: Electrical Pipe-Line, July 1946 Popular Mechanics - RF CafeOnce World War II was over, a flood of technical information poured out of government, academic, and corporate research and manufacturing institutions. Making available such data was a promise made by the Department of War to a citizenry which largely supported the wartime effort to maximize resource usage for defeating Axis powers. People and businesses provided raw and recyclable materials as well as services in the interest of assuring our fighting men had every tool at their disposal while fighting for the folks back home. To today's unpatriotic and selfish population it might seem like a Pollyanna and even unlikely view of the world, but that was the case back in the day. Bell Telephone Laboratories (aka Bell Labs) contributed Big League (not "bigly," as ignoramuses claim Trump said) to the pushing forward of technical frontiers. A major development was use of waveguide for microwave systems like radar. As mentioned in this 1947 Popular Mechanics magazine infomercial, their engineers had already figured out how to not only transport radio frequency signals within the confines of waveguide...

Speaking of TVI Issues...

The Severn Bore Tidal Wave: TV Interference - RF CafeHere's a great bit of TVI (television interference) sleuthing for you, as told by RF Cafe visitor Andrew B. "A customer called me with a strange issue, back in the analogue transmission days (UHF). Twice a day at roughly the same time [12 hours apart], BBC channels would completely disappear, only to reappear around 30-45 minutes later. I replaced the antenna, the cable, even the chimney bracket and pole, but nothing fixed the issue. I then arranged with the customer to be on the roof at the time that the issue usually happened. I plugged my meter into the aerial and waited. Sure enough, the SNR shot up and as it did I looked around to see what it could be. Luckily I noticed something from my excellent viewpoint on the ridge next to the chimney! We have a tidal river called the River Severn, and twice a day we get a bore wave as the water rises and recedes. The transmitter was on the other side of this river, around 40 miles away. I then read about how reflections could cause ghosting due to multipathing, and in some cases caused complete loss of desired signal, and how a stacked array could solve these issues. Long story short, using the horizontal stack method, we managed to eliminate the issue completely!"

Mac's Service Shop: TVI from the Victim's Viewpoint

Mac's Service Shop: TVI from the Victim's Viewpoint, March 1972 Popular Electronics - RF CafeWhen I read this installment of Mac's Service Shop, in the March 1972 issue of Popular Electronics magazine, the first thing that came to mind was my own experience with television interference (TVI) when I was a kid. In that case, the transmitter of my radio control system for a model airplane was the culprit. The frequencies and channels are almost exactly the same as reported in this infodrama™. In the 1970s, citizen band (CB) radios operated in the 27 MHz realm, as did my R/C transmitter. During summer vacation from junior high and high school, I would run my model airplanes up and down the street in front of my house, getting up just enough speed to lift off and then immediately chopping the throttle and landing. As soon as the transmitter was switched on, nearby housewives would lean out their doors and yell at me for screwing up "As the World Turns" or "All My Children." They were not particularly happy with noise from the engine, either. I eventually adjusted my operation times to avoid the afternoon soap opera prime time...

"NASA Spinoff" Technology Transfer Program

NASA Technology Transfer Program - RF CafeEver since the manned space exploration programs began at NASA (National Aeronautics and Space Administration), controversy over both the financial costs and the cost in lost opportunity for other government funded programs has existed. Many people, myself included, have always championed the efforts and believe the axiom of the whole being greater than the sum of the parts applies to the efforts. Opponents say resources would be better spent here on Earth. In fact, we have always done both. To address the issue, NASA Spinoff was created to publicize the byproducts of the space program that benefit other areas of research, manufacturing, and society. Since at least the 1970s, NASA has published a monthly magazine entitled NASA Tech Briefs to inform the public on their activities, inviting readers to submit ideas and to request information on how to apply NASA research to commercial applications. I have been a regular reader since around 1980.

Walkie-Talkies: Something for Everyone

Walkie-Talkies: Something for Everyone, April 1974 Popular Electronics - RF CafeWhat stood out to me when reading this 1974 Popular Electronics magazine article on walkie-talkies is a statement made near the end where the author claims regarding loaded whip antennas, "Transmit losses are many times greater than receiver losses." The last time I checked, passive antennas are reciprocal devices, so gains and losses should be the same for transmit and receive. Maybe he meant that for a given antenna loss value in decibels, that the absolute power loss is greater at the transmitter end. My main reason for posting the article is because it pretty much completes the evolution cycle of walkie-talkies, which started life being called handie-talkies when being developed during World War II as lightweight, portable 2-way radios which could be deployed in regions of difficult travel and even carried by paratroopers. Nowadays, most "serious" handheld transceivers operate in the 462-467 MHz Family Radio Service (FRS) band, rather than in the 27 MHz Citizens Band as did early models...

RF & Electronics Stencils for Visio

RF & Electronics stencils for Visio r4 - RF CafeWith more than 1000 custom-built stencils, this has got to be the most comprehensive set of Visio Stencils available for RF, analog, and digital system and schematic drawings! Every stencil symbol has been built to fit proportionally on the included A-, B-, and C-size drawing page templates (or use your own page if preferred). Components are provided for system block diagrams, conceptual drawings, schematics, test equipment, racks, and more. Page templates are provided with a preset scale (changeable) for a good presentation that can incorporate all provided symbols...

Inventors of Radio: Julius Edgar Lilienfeld

Inventors of Radio: Julius Edgar Lilienfeld, December 1964 Radio-Electronics - RF CafeHere is yet more evidence of my oft-made claim that Germany might have dominated the world as a technological and financial superpower if it had not instigated two world wars. A huge amount of ingenuity and ability to convert ideas into reality has come out of Germany over the course of centuries. Oppressive and often inhumane government behavior caused a lot of that talent to emigrate to other countries, so the opportunity was lost. In this instance, I refer to Julius Edgar Lilienfeld, who not only produced the first sample of liquefied helium, but also is credited, according to this 1964 Radio−Electronics magazine article, for developing the first semiconductor devices for amplification. U.S. patent number US1745175A was awarded on January 28, 1930 (filed on October 8, 1926) for what was essentially a field effect transistor. Lilienfeld became a U.S. citizen in 1935. To be fair, I will also note that many of those fled-to countries are today as bad or worse than Germany was then...

Transition Transistors Downsize Next-Gen Tech

Transition Transistors Downsize Next-Gen Tech - RF Cafe"By better taming the Jekyll-and-Hyde nature of an alternative to the semiconductor - one that transitions from electricity-resisting insulator to current-conducting metal - Nebraska's Xia Hong and colleagues may have unlocked a new path to smaller, more efficient digital devices. The team reports its findings in the journal Nature Communications. The semiconductor's ability to conduct electricity in the Goldilocks zone - poorer than a metal, better than an insulator - positioned it as the just-right choice for engineers looking to build transistors, the tiny on-off switches that encode the 1s and 0s of binary. Apply some voltage to the control knob known as a gate insulator, and the semiconductor channel allows electric current to flow (1); remove it, and that flow ceases (0). Millions of those nanoscopic, semiconductor-based transistors now coat modern microchips, switching on and off to collectively process or store data. But as minuscule as the transistors already are, the demands of consumers and competition continue pushing electrical engineers to shrink them even further, either for the sake of squeezing in more functionality or downsizing..."

Electronic Coupling Quiz

Electronic Coupling Quiz, August 1973 Popular Electronics - RF CafeA score of 80% is nothing to brag about, but at least I got all the easy ones right. A couple of them I guessed at based on how the circuit looks - like the one with the "gimmick" coupling. This quiz by Popular Electronics magazine quizmaster Robert P. Balin tests your knowledge of coupling circuits. If it had not been for studying for my Ham radio license tests, I would not have recognized the gamma matching circuit. Fewer and fewer people nowadays - at least as a percentage of those engaged in electronics - are familiar with fundamental concepts of circuit design (truthfully, I've forgotten a lot of what I learned decades ago). Entire products can be designed nowadays using just integrated circuits, a handful of power supply decoupling capacitors, and maybe a little software code...

Exploring Uncommon Applications of Isolation

Exploring Uncommon Applications of Isolation - RF CafeI admit that the main reason I'm posting this is because of the cool looking hand-wound isolation transformers. With all the pre-made, integrated components and assemblies that are the rule these days, it's nice to see such an exception. You will find this a lot with designers and builders of RF transmitter circuits. This one happens to be for a DC power supply. It begins: "Electrical isolation is defined as the separation between two circuits that will restrict the direct current and any unwanted alternating current in a power supply. One of the main reasons that a circuit may need isolation is to protect it from damaging or dangerous currents and/or voltages. Isolation will also prevent dangerous voltages from passing to the operator during an electrical fault/failure or lightning surge. However, the flow of AC current transfer of power and signal will still be able to flow between two circuit system areas. This article describes some various application examples that need isolation. Here are only a few general examples: Protecting human operators and low-voltage circuitry from high voltages. Improving noise immunity. Handling ground potential differences between communicating subsystems. Now let's get down to some of the key areas that use isolation..."

Comics with an Electronics Theme

Comics with an Electronics Theme, May 1972 and July 1972 Popular Electronics - RF CafeHere are a couple more tech-themed comics from vintage Popular Electronics magazines. Only one comic appeared in each of the May 1972 and July 1972 issues, so I combined them onto a single page. What's that guy in the May comic in the background doing? Anyone remember those pieces of furniture that were once a staple of engineering offices? I spent many an hour sitting at such drafting tables drawing schematics and block diagrams as an electronics technician. By the time I earned my BSEE, everyone was using computer CAD software, albeit still rather crude by today's standards. The July comic reminds me of a scenario that might have appeared in one of the old Calvin and Hobbes comic strips that graced our newspapers up through the end of 1995. Calvin's father, in case you didn't know, was a patent attorney...

Promote Your Company on RF Cafe

Sponsor RF Cafe for as Little as $40 per Month - RF CafeBanner Ads are rotated in all locations on the page! RF Cafe typically receives 8,000-15,000 visits each weekday. RF Cafe is a favorite of engineers, technicians, hobbyists, and students all over the world. With more than 17,000 pages in the Google search index, RF Cafe returns in favorable positions on many types of key searches, both for text and images. Your Banner Ads are displayed on average 280,000 times per year! New content is added on a daily basis, which keeps the major search engines interested enough to spider it multiple times each day. Items added on the homepage often can be found in a Google search within a few hours of being posted. If you need your company news to be seen, RF Cafe is the place to be...

Radar Takes Cover Under the "Big Top"

Radar Takes Cover Under the "Big Top", September 1949 Popular Science - RF CafeWhen reading this article about a 50-foot-diameter inflatable radar antenna dome from a 1949 issue of Popular Science magazine, I was surprised to learn it was only rated for withstanding 2 inches of snow. The story says snow or ice, but 2 inches of ice would typically weigh an lot more than 2 inches of snow - even wet snow. That is not to say it cannot survive in regions where more than 2 inches of snow is likely to fall. It cleverly uses a repetition of partial deflation / inflation actions to flex the surface, thereby causing the snow and/or ice to lose its grip and slide off. That sounds good in theory, but I wonder how successful it really was under real-world conditions. If you do an Internet search on some of those huge inflated sports arena domes in snowy locales, you'll find plenty which collapsed under heavy snow loads. That happened to the Erie Sports Arena when we lived there.

Intuitive Machines IM-1 Moon Lander Images

Intuitive Machines IM-1 Moon Lander Images - RF Cafe"Odysseus continues to be in excellent health, and flight controllers are preparing planned trajectory correction maneuvers to prepare the lander for lunar orbit insertion. Since the IM-1 Mission launched on SpaceX’s Falcon 9 rocket, flight controllers on the Company's red, white, and blue teams have been learning more about the lander and how to efficiently fly the mission to return the United States to the surface of the Moon..."Some people celebrate the transfer of responsibility for manned and unmanned space exploration vehicles to private contractors, citing lower costs and competition. You cannot convince me that the true cost of any given private contractor system is any less than a NASA project, especially given duplications of efforts and indirect payments outside of the formal contract. Fortunately, many of the private companies are doing an excellent job, but I'd rather see "NASA" painted on the side.


Di-Di-Di-Di-Di-Di-Di-Di-Dit*, November 1966 Popular Electronics - RF CafeIs it permissible to say, "Pig Latin," these days without being jailed for engaging in hate speech or being accused of cultural insensitivity? ...not that I really care. Carl Kohler's/ story from the November 1966 issue of Popular Electronics magazine had me waxing nostalgic over a similar scenario from my own boyhood. It begins with Mrs. Kohler (aka "Goodwife") suggesting that she and Mr. Kohler resort to speaking in Pig Latin in order to prevent their mischievous sons from learning where the Christmas presents were being hidden. My parents did exactly the same thing to my sisters and me - and that was in the 1960's. My older sister, Gayle, and I made a point of learning Pig Latin ourselves in order to thwart the evil scheme. By the next Christmas we were able to discern that a certain corner of the attic was the secret hiding place. Our rancher style house's attic was not very big, but then neither were we at the time. We anxiously awaited the evening shortly before Christmas when our parents went to the holiday party put on by the local kids' sporting association, and had those pull-down stairs opened almost before the car got out of the driveway...

Reactel Filters Shipping

Reactel Filters Shipping - RF CafeJim Assurian of Reactel wearing Maryland Flag pants - RF CafeSince it was established in 1979, Reactel has become one of the industry leaders in the design and manufacture of RF and microwave filters, diplexers, and sub-assemblies. Company president Jim Assurian's pride in his resident state of Maryland (my home state) is apparent in his company's promotions, and even his attire! From Reactel's LinkedIn feed: "Here is one of the many filters shipping from Reactel, Incorporated this week. Today, we are featuring a UHF-Band Discrete Component Diplexer intended for low-frequency communication applications. We manufacture RF, Microwave & Millimeter Wave Filters, Multiplexers and Multifunction Assemblies up to 67 GHz and can design a unit to fit your specific application..."

News Highlights: Popular Electronics

News Highlights, July 1972 Popular Electronics - RF CafeEngineering and science magazines, websites, and discussion panels frequently report on and lament the lack of women and minorities in both realms. You might think this is a relatively new concern since, but as evidenced by this 1972 Popular Electronics magazine tidbit the effort to attract women and minorities into the fields has been going on for half a century. At the time, women and minorities made up about 2% of undergraduates in engineering curricula. The proportion was 20% as of 2015 (a 10x increase) according to a recent report by the American Society for Engineering Education (ASEE). During that same time period (1970), according to the National Center for Education Statistics the overall split between men and women in college (in the U.S.) was 4,249,702 3 males and 3,118,942 females (57% males / 43% females). As of 2105 the split was 7,499,837 males and 9,536,941 females (44% males / 56% females). The ratio has reversed and today favors women to the degree it favored men in 1970. That must be why there are so many government programs now which are attempting to get men back into college. Oh, wait, no there's not...

Electronics Theme Crossword Puzzle for February 18th

Electronics Theme Crossword Puzzle for February 18, 2024 - RF CafeThis custom RF Cafe electronics-themed crossword puzzle for February 18th contains only clues and terms associated with engineering, science, physical, astronomy, mathematics, chemistry, etc., which I have built up over more than two decades. Being the 18th day, words containing the letter "R" are marked with an asterisk (*). Many new words and company names have been added that had not even been added to the world's technical lexicon when I started in the year 2002. As always, this crossword contains no names of politicians, mountain ranges, exotic foods or plants, movie stars, or anything of the sort unless it/he/she is related to this puzzle's technology theme. You might, however, encounter the name of a movie star like Hedy Lamarr or a geographical location like Tunguska, Russia, for reasons which, if you don't already know, might surprise you. The technically inclined cruciverbalists amongst us will appreciate the effort. A full list of all RF Cafe crosswords is at the page bottom. Enjoy!

Cartoons Teach Physics with a Smile

Cartoons Teach Physics with a Smile, June 1948 Popular Science - RF CafeEvidently I am in good company with my appreciation for good humor related to science and technology. This "Cartoons Teach Physics with a Smile" article appearing in the June 1948 issue of Popular Science magazine cites the College of the City of New York's Professor Robert S. Shaw's use of such hilarity in his physics classes. Whereas the artists who created these comics probably did not intend to illustrate a particular physics principle, many people familiar with the principles are quick to recognize what is going on. As can be seen in the hundreds of electronics and technically themed comics on the pages linked at the bottom of the page, those which showed up in publications like Radio and Television News, Short Wave Craft, Radio-Electronics, QST, and Popular Electronics were specifically created for the type audience that reads them. BTW, I learned a new word here: isostasy. An unrelated story that occupied the other half of one of the pages reports on a problem telephone cable stringers had with gophers chewing through the insulation - definitely not funny at the time to the engineers, but kind of funny in retrospect...

Espresso Engineering Workbook - RF Cafe

About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

1996 - 2024


Kirt Blattenberger,


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 World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

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