An Experiment with Gravity

This is pretty cool. If I owned a good receiver (which I don't), I would definitely give it a try. In 1970 when this Popular Electronics article was written, a lot of Hams were still using tube receivers so the recommendation to let the equipment warm up for several hours prior to making the fine frequency adjustments was good advice. Nowadays the warm-up time and stability of receivers should permit 30 minutes or so to suffice (even ovenized frequency references need time to stabilize when first powered up). Unless I missed it, the author does not explicitly state that the frequency change measured over time is due to gravity acting on the mass of the crystal reference, but I suspect that is his intention since part of the experiment involves disconnecting the antenna and shielding the receiver from outside interferers. Over a lunar month period (29.5 days) we experience a leap tide and a neap tide which maximizes and minimizes, respectively, the vector sum...

PartSim Online Circuit Analysis Simulator

Simulation Program with Integrated Circuit Emphasis (SPICE) has been around since 1973. The basic computational engine has always been open source. It began as a simple analog circuit simulator that took a structured text file as the input net list and provided a text file output that contained the calculated values that the user specified such as DC bias points, transient analysis, and AC analysis. Online simulators are now going through the same kinds of growing pains that the earlier iterations of PC-based SPICE simulators experienced. Most are really clunky and always seem to be missing key features and/or easily accessed features - like rotating components on the schematic or routing interconnect lines. Aspen Labs, in a partnership with Digi-Key, has a free online analog circuit simulator called PartSim that seems to have conquered most of the basics. Being able to save and recall your work is a huge benefit...

Sangamo Electric Company Capacitors

Sangamo Electric Company was a "heap" big name in capacitors in the realm in the middle of the last century. The company always featured an American Indian in its electronics magazine advertisements, and usually also included some form of "indian-ese" statements as part of the sales pitch. Of course such marketing schemes would be vehemently raided and those responsible figuratively "scalped," if you will pardon the gratuitous expressions. As with using names like the Washington Redskins, the Atlanta Braves, the Chicago Blackhawks, and the Cleveland Indians to appropriate and celebrate the bravery and might of the named peoples, Sangamo implied quality, durability, and reliability of its products through an association with American Indians. That does not matter to people who seek to create discord amongst the population while, in many cases, seeking notoriety and financial gain for themselves. Sangamo Electric was located in Marion, Illinois, an area where a few other uses of Sangamo are used, but I could not find any direct reference to a Sangamo tribe...

Coming "Secret" Weapons - Sound Familiar? 

Usually, when I read about yet another launching of rockets from Gaza into Israel, what comes to mind is the barrage of V1 Buzz Bombs and ultimately the V2 rockets that Germany terrorized London with during World War II. Although overall not very effective individually, they did cause brief spells of horror for the localized group of people that were affected through maiming, killing, or property destruction. The difference between the Nazi's weapons and Hamas' weapons is that the Germans didn't depend on other terrorist entities to supply them with their weapons of destruction; they were brilliant people who had evil intentions of world domination. Hugo Gernsback writes here that the initial plan for the V2 was to deliver an electromagnetic impulse that would disable all electrical and electronic systems within 8,000 feet of its detonation point - what we nowadays call an electromagnetic pulse (EMP) weapon. BTW, the 'V#' designation stood for...

Predicting the Future of Radio Communications

Syzygy is a great word for a Scrabble game. If you use it on a Triple Word Score (TWS) space where the "Z" sits on a Double Letter Score (DLS) space, it will net you 105 points. About the only way to do better is to use all 7 letters on a TWS play, where you earn 50 bonus points added to your word score (I've done it twice in the last year). Syzygy is an astronomical term referring to an alignment of three or more celestial bodies - not necessarily in exact alignment, but within a few degrees. Astrologers (not to be confused with astronomers) have since their knuckles no longer dragged on the ground exploited such scenarios to predict various events both good and bad. That was even before they knew those "wandering" orbs (planet means "wanderer") were different than the (seemingly) stationary points of light. Until Galileo turned his rudimentary telescope on the planets, the only celestial objects with a discernable disk shape were the sun and moon, and possibly the earth. But I digress. It was long thought that the vector sum of gravitational influences was responsible for certain phenomena on our planet, including weather, tides, and earthquakes...

How Soon Shall We Have Television?

If you think government bureaucracies meddling in the affairs of private business is a relatively new phenomenon, think again. Elected and unelected persons and agencies have since the inception of control over the populace made it their business to dictate which pursuits of technology are sanctioned and which are not. Often, the motivation lies in who within those bureaucracies stands to benefit monetarily from the decision. In this story lamenting the painfully and, in the author's opinion, unnecessarily long time experienced in bringing commercial broadcast television to the marketplace - in 1935. One of the primary stumbling blocks was the Federal Communications Commission (FCC) preventing companies from televising paid commercials during programs because, in the FCC's view, picture quality was not good enough to serve advertisers' interests. In the process...

G-String Transmission and Helical Wave Coils

Who says engineers and scientists have no sense of humor? This is not an April Fools joke or an attempt to punk you into reading the story. An Internet browser with strict parental control settings enabled might even prevent this page from even being displayed. In actuality, the term "G-String Transmission Line" was so dubbed by its inventor, Dr. George Goubau, as a tribute to his own name - both first and last. Out of an abundance of caution, I reference the Library of Congress' "G-String" entry for the good doctor and the device's legitimacy. A drawing similar to Fig. 1 in this 1951 issue of Radio-Electronics magazine can be seen on the chalkboard behind Dr. Goubau in the LoC photo. To be honest, I do not recall ever having heard of the G-string transmission line. Its enthusiastically, nearly evangelically extolled virtues must not have panned out in real-world practice because we do not find G-strings...

The FM Radio Boom

Hugo Gernsback is not necessarily a household name in 2020, but in the early to middle 20th century, he was fairly well known in both the hard science and science fiction realms. He was a prolific author of books and magazines in both areas, applying his profound knowledge of technology and his ability to foretell the futures of many aspects of communications, mechanics, electronics, and marketing and societal behavior to the aforementioned. If you are a regular RF Cafe visitor, you have seen very many articles written by Hugo Gernsback reproduced. This particular work of prognostication appeared in a 1947 issue of his Radio-Craft magazine. It presciently claimed that a post-war boom in consumer buying after half a decade of sacrifice of creature comforts for the good of the country and world would feed a significant adoption of FM radio over...

E-flite Mini Pulse XT's Brushless ESC Waveform

Much more than just a self-serving video of my new R/C airplane flight agility, this model represents a plethora of modern electronics. Although the radio control system in this plane is a standard narrow band FM variety on 72.170 MHz (as opposed to my 2.4 GHz, spread spectrum system), the motor is a state-of-the-art 3-phase brushless model (E-flite 450)with a sensorless electronic speed control (E-flite EFLA331, 20 A). Power for both the radio and the motor is supplied by a 3-cell (11.1 V) lithium polymer (Li-Po) battery rated at 2,100 mAh with a 15C discharge current capacity. There was a time not so long ago when no one though that electric power could ever provide a equivalent to the nitro methane gulping internal combustion engines, but the time has come. This all-electric setup is fairly small in size, but there are much larger motors...

A Homebrew Soldering Gun

We take a lot for granted these days with the seemingly unlimited availability of cheap stuff of all kinds - some of it complete junk and other of it pretty darn good. That goes for electronics components and complete products and test equipment, tools, automobiles, appliances, and utensils, clothing, medical equipment - you name it. Something as simple as a pistol-type soldering gun can be purchased at just about any hardware or home store, and at a price that when adjusted back to equivalent money in the 1940s would be amazingly cheap even then. For instance a Weller Soldering Gun kit from Lowes sells for $39.48 today (less when on sale), which would have been $3.44 (per the BLS Inflation Calculator) in 1947 when this article showing how to build your own appeared in Radio-Craft magazine. If a soldering gun could have been purchased for a mere $3.44 in 1947, there would have been no need to publish such an article because its cheapness would have obviated...

Afghanistan's Buried Riches: Rare Earths & More

Have you heard about this? I hadn't. If you think the only goal in Afghanistan is to stamp out the Taliban, think again. An article in the October 2011 issue of Scientific American details the extensive mineral surveys that have been carried out there in the last year or so. Afghanistan is home to what may be the largest cache of rare earth elements in the world, with a potential to replace China as the largest extractor (~90%) of those atoms that lie in the lanthanide and actinide regions of the periodic table - the two rows that are typically pulled out of the chart. China, you may have heard, is severely restricting the export of rare earths - wanting to keep it for themselves - thereby triggering a near panic. Prices are rising so alarmingly that reopening mines in the U.S. has once again become profitable in spite of the crippling regulations that years ago closed down operations here (huge loss of jobs and tax revenue) and forced us to become reliant on offshore supplies...

Engineering & Science Crossword Puzzle May 3, 2020

As with my hundreds of previous engineering and science-themed crossword puzzles, this one for May 3, 2020, contains only clues and terms associated with engineering, science, physical, astronomy, mathematics, chemistry, etc., which I have built up over nearly two decades. Many new words and company names have been added that had not even been created when I started in the year 2002. You will never find a word taxing your knowledge of a numbnut soap opera star or the name of some obscure village in the Andes mountains. 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.

E-flite Blade CP R/C Helicopter 4-in-1 Teardown

E-flite's Blade CP radio controlled electric helicopter comes from the factory with a 4-in-1 electronics unit that contains a 6-channel receiver that performs the functions needed for motor control, piezoelectric gyroscope, BEC (battery eliminator circuit), and ESC (electronics speed control). It also includes a dual-gimbal transmitter with an idle-up switch for transitioning to aerobatic mode where both positive and negative pitch can be commanded to the rotor head. My Blade CP has always flown well, but from the very beginning it has been prone to sudden, uncommanded control movements (glitches). The results have varied from slight jerkiness in the flight to a sudden high speed climb-outs (really bad when inside).

New York Taxing Out-of-State Healthcare Workers

"On the way back to your home state, don't let the door hit ya' where the good Lord split ya'. Oh, and we'll be sending you a tax bill in appreciation for your selfless sacrifice in caring for our citizens." That is basically the sentiment of New York's governor, who after literally begging out-of-state healthcare workers to come to NY City amongst the Chinese COVID-19 breakout, has declared that his financially mismanaged and cash-strapped state is going to collect income tax from the aforementioned good Samaritans.

All Channel Antenna Corporation

Phased vertical stacks of two or more antennas were fairly common in the television realm - especially once color broadcasts became more dominant in the 1950s. Up to 3 dB per additional antenna is possible, but due to various non-ideal physical parameters (summed phase angle, imperfect antenna geometry, etc.), realized gain is typically in the 2.5 to 2.8 dB range. Higher signal to noise ratios were needed to guarantee good color separation with the National Television System Committee (NTSC) and stereo channel audio separation with the advent of Multichannel Television Sound (MTS). As you might expect, companies appeared claiming to have invented physics-defying antennas that "outperform all present antennas." This particular "Super 60" model from All Channel Antenna Corporation further claims to outperform antennas that use a mechanical rotator (see my Alliance U-100 Tenna-Rotor) by virtue of its 9-position electronic phase switching...