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Homepage Archive #13


Dilbert Electronic Candy

Dispenser Update

Dilbert Electronic Candy Dispenser Update - RF CafeNo, it does not dispense electronic candy. A few years ago my daughter gave me a second-hand Dilbert candy dispenser, but the mechanism didn't work. It turns out the battery holder was wired backward from the factory so it could never have worked. Anyway, there is one part that is especially frustrating to remove (the computer front panel), and many people have written to me asking for details. Have just now received another request, I decided to add that info to the web page.

RF Cafe Visitor Finds His Great

Grandfather in 1944 QST Article

Hams in Combat - One Life to Give, July 1944 QST - RF CafeOne of the reasons I go to the trouble of posting the old magazine articles from SQT, Popular Electronics, Electronics World, etc., is to allow people searching for stories about relatives a better chance of finding information. A couple days ago the great grandson of a WWII reconnaissance officer who died in the line of duty. Captain William H. Graham was a Ham radio operator before the war, holding call sign W9BNC. The story was told in the July 1944 edition of QST under the title of "Hams in Combat - One Life to Give." Read the note sent by his grandson.

Government Is Bombarding

Citizens with Radiation!

The Government Is Bombarding Citizens with Radiation! - RF Cafe

Please, even if you sincerely believe that the government is bombarding you with radiation in order to control, maim, or kill you, do not call me. As a former agent of the U.S. government's National Unit for ciTizen Subduance (code word: NUTS), all of my communications are constantly under surveillance, so merely contacting me by telephone, e-mail, Skype, telegraph, message in a bottle, or smoke signals virtually guarantees that "they" will find you and increase the attack already underway against you. For all that is Holy, spare yourself from the personal torment and hide while you still can! Seriously, four or five people call me every year wanting to tap into my expertise on RF energy to help them validate their suspicion - no, wait, absolute certainty - of currently being the victims of a huge government conspiracy whereby special frequencies that have been determined to allow mind control are attempting to turn them into mindless subjects. I just got off the phone with another such individual. All sound genuinely friendly and inquisitive regarding some kind of RF principle they are not totally knowledgeable about, and admit to being new to the world of radio frequencies. Usually...

RF Engineering Theme

Crossword for 12/30/2012

For the sake of avid cruciverbalists, each week I create a new crossword puzzle that has a theme related to engineering, mathematics, chemistry, physics, and other technical words. You will never be asked the name of a movie star unless he/she was involved in a technical endeavor (e.g., Hedy Lamar). This is the December 30, 2012 puzzle.

Loose Parts Comic

'Norse Code"

Loose Parts "Norse Code" - RF CafeI've recommended some tech-themed "Loose Parts" comics in the past (here and here). This one will give you a chuckle, particularly if you are a CW guy (or gal).

Notable Quote

"I have an app on my phone that lets me talk to all the people around me. It shuts the phone off." - RF Cafe"I have an app on my phone that lets me talk to all the people around me. It shuts the phone off." - Mark Simone, talk show guy

Tales from the Cube:

A Dark Story

Tales from the Cube: A Dark Story - RF CafeThis intriguing story of troubleshooting prowess - and luck - will appeal to people like me who were around in the electronics industry in the 1970s and 1980s when CMOS logic was just coming onto the scene. Everyone loved the low power aspect of CMOS and rushed head-long into implementation, then had to put a lot of time into modifying circuits to rectify issues. A new set of design rules were required. I won't spoil the solution, but will say after you read this installment of Tales from the Cube, you will likely recall from decades ago at least one similar "ah-ha" moment in the lab.

Featured Book: RF and
Microwave Radiation Safety

RF and Microwave Radiation Safety, by Ronald Kitchen. A practical handbook for all involved in electronic design and safety assessment, RF and Microwave Radiation Safety covers the problems of RF safety management, including the use of measuring instruments and methods, radiation hazards and risks resulting from electromagnetic interference, as well as reviewing current safety standards and the implications for RF design. The second edition takes into account a wide range of technical and legislative changes, and has been revised in line with the latest EU and international standards. Issues raised by increasing levels of microwave pollution from mobile phones and other sources are also confronted.

Practical Applications

of Simple Math

Practical Applications of Simple Math - Part II, June 1944 QST - RF CafeRecognizing that many people were reluctant to approach the theoretical aspect of electronics as it applied to circuit design and analysis, QST (the American Radio Relay League's monthly publication) included equations and explanations in many of their project building articles. Occasionally, an article would be published that dealt specifically with how to use simple mathematics. In this case, the June 1944 edition, we have the second installation of at least a four-part tutorial that covers resistance and reactance, amplifier biasing (tubes since the Shockley-Bardeen-Brattain trio hadn't invented the transistor yet) oscillators, feedback circuits, etc.

IEEE:  Engineering in

Biology and Medicine

IEEE in Biology and Medicine Engineering - RF CafeMiracle inventions in medicine and biology often require the assistance of electrical engineers to provide an interface for measurement and/or control. Ingestible and implantable wireless probes and monitors, wearable brain wave caps, robotic limb replacement and assistance devices, imaging equipment, and nanotechnology are a few of the applications requiring an EE partnership. Many doctors were first engineers before getting a medical degree, and as such do their own circuit and/or mechanical and/or software design. The IEEE is executing (maybe the wrong verb to use when addressing medical topics) an awareness effort to hopefully attract engineers into the field. Some projects have you working directly with patients and volunteer test subjects, so if you are one of those fabled non-introverted engineers, this might be the career course for you.

2013 IEEE RFIC Symposium

Call for Papers

2013 IEEE RFIC Symposium Call for apers - RF CafePlans are underway already for the 2013 IEEE RFIC Symposium in Seattle, Washington, on June 2-4.. As such, a Call for Papers has gone out

Please visit Noisewave in

Appreciation of Their Support

Noisewave makes standard and custom noise test solutions to meet commercial and military wireless applications. Noise diodes in TO-8, DIP, or SM pin packages. Calibrated broadband sources ideal for NF measurement & BIT.

Improving the Receiver Using

a Screen-Grid Coupling Stage

Improving the Receiver Using a Screen-Grid Coupling Stage - RF CafeIn December of 1931, the discovery of deuterium (aka 'heavy water) was announced by Harold Urey, Japan abandoned the gold standard, the New York Metropolitan Opera broadcasted an entire opera over radio for the first time (on Christmas day), and the ARRL's QST magazine published an article about how to improve a receiver by using a screen-grid coupling stage on vacuum tubes. A 'tickler coil' is introduced via a tuned circuit to provide a small amount of positive feedback to the grid in order to make the amplifier stage more sensitive in the band of interest. Care needed to be taken to avoid so much feedback that oscillations could occur. As with most of these old articles...

Many Thanks to JFW

Electronics for Backing RF Cafe

JFW is a major manufacturer of attenuators, RF switches, specialized test systems for use in the cellular, telecom, OEM test equipment, medical, automotive, defense, and automated test systems markets. JFW offers custom designs at catalog prices, fast delivery and no NREs!

Please Visit Linx Technologies

in Appreciation of Support

Linx TechnologiesLinx Technologies' RF modules, remote controls, evaluation kits and master development systems feature straightforward hardware configuration and clear documentation, making it simple for engineers and hobbyists to integrate wireless features without the hassle and expense of engineering RF functionality from scratch.

Vintage Electro-Voice

Microphone Advertisement

Electro-Voice Microphones Advertisement, February 1943 QST - RF CafeHere is an advertisement for Electro-Voice Manufacturing Company microphones that I scanned from page 101 of my copy of the February 1943 QST magazine. As with many companies during the World War II era, this one's theme is the service their products are providing to America's servicemen. Per the ad, "If you were receiving radio messages from men in the midst of ear­splitting battle noises, you'd hear crisp speech undistorted by background sound effects. Electro-Voice Microphones, in military service, are helping to make it possible. Similar microphones, designed to achieve such results, will be available for specific commercial applications ... after our wartime job is done..."

Thanks to Apex Wireless for

Their Continuing Support

Since 1985, Apex Wireless has offered consulting, engineering, and design services focusing on high-performance, cost-optimized products that employ wireless RF transmitters, receivers, and transceivers. To complement our RF design expertise, they work with local experts in DSP, ultra low power design, packaging, certification, and manufacturing.

How to Draw a Circle

with a Square

Drawing a Circle with a Framing Square and 2 Nails - RF Cafe Smorgasbord"Squaring the circle" may as yet be an unattainable goal for even the best mathematicians, but the November 2012 edition of The Family Handyman magazine had a tip for how to use a square (of the framing type) and two nails to draw a circle. This is what it said: "Make a Circle with a Square - Here's a tip for laying out small circles or parts of circles. Tack two nails to set the diameter you want, then rotate a framing square against the nails while you hold a pencil in the corner of the square. You might need to rub a little wax or some other lubricant on the bottom of the square so it slides easily. Don't ask us why this process works; all we know is that it does." They're either very honest or they don't think the average reader would understand the explanation. The Pythagorean theorem is the key, of course, for explaining the reason. For any right triangle: a2 + b2 = c2, where 'a' and 'b' are the lengths of the two perpendicular sides, and 'c' is the length of the hypotenuse...

Tales from the Cube: Out-of-

Spec Problem with a Long Tail

Tales from the Cube: Out-of-Spec Problem with a Long Tail - RF CafeI like the artwork that usually accompanies these 'Tales from the Cube' stories of troubleshooting prowess on the part of fellow engineers. This installment, "Out-of-Spec Problem with a Long Tail," reaches way back to the dawn of computer-based circuit analysis to tell how a particularly troublesome problem was solved by running a Monte Carlo routine to discover the culprit. Here is an explanation of a 'long-tail-pair differential amplifier' in case you've never heard of it.

Many Thanks to Oscilent

for Continued Support

Oscilent is a manufacturer of frequency control products offering design and production expertise in SAW Filters, quartz crystals, crystal oscillators & Filters, and ceramic resonators. Their product line includes extensive custom and standard capabilities in TCXOs and VCXOs, in addition to full design and development capabilities in each focus product category. Oscilent serves OEM, design, and CM customers in all major world development and manufacturing zones.

Science & Engineering Theme

Crossword for 12/23/2012

For the sake of avid cruciverbalists, each week I create a new crossword puzzle that has a theme related to engineering, mathematics, chemistry, physics, and other technical words. You will never be asked the name of a movie star unless he/she was involved in a technical endeavor (e.g., Hedy Lamar).

About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

Copyright: 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...

Copyright  1996 - 2026

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All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

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