Teach Kids Electricity

Some things never change - at least at the fundamentals level. Electric circuits is one of those things. I don't remember when I first became interested in electrical apperati, but it must have been due to a natural affinity to the science because nobody in my family or my circle of friends expressed any interest. I was the odd man (or boy) out on my street, because while all the other kids were playing baseball, basketball, and football, I was sticking forks in electric sockets and disassembling flashlights, battery-powered toys, and building Erector Set contraptions using the included electric motor. That's not to say I ever got really good at it, but significantly better than I ever got at playing sports...

Impedance Matching CB Antennas

You would be forgiven in this era of ubiquitous cellphone usage for thinking maybe Citizen Band (CB) radios are only used these days by techno-throwbacks like myself, but the fact is many truckers still use them for convenience as well as to avoid having all their communications intercepted, monitored, and recorded by government agencies. It can be a deceiving sense of privacy though, because police officers often monitor CB radio transmissions while in patrol cars, and even solicit the assistance of other CBers in identifying and apprehending suspected transgressors - an advantage of public, unencrypted conversation afforded law enforcement which is not available with cellphones. Also, CB transmission, even though usually regarded as "hearsay" in legal venues, has many times been admitted as evidence in cases where "present sense impression," "excited utterance," or some other special...

AI Math Tricks no Good for Science

I have experienced the problem with low precision AI calculations; however, it will use high precision if specifically instructed to do so. "AI has driven an explosion of new number formats - the ways in which numbers are represented digitally. Engineers are looking at every possible way to save computation time and energy, including shortening the number of bits used to represent data. But what works for AI doesn't necessarily work for scientific computing, be it for computational physics, biology, fluid dynamics, or engineering simulations. IEEE Spectrum spoke with Laslo Hunhold..."

Science & Engineering Crossword Puzzle

This week's Science & Engineering Crossword Puzzle, as is the case with all RF Cafe crossword puzzles, has only words and clues related to science and engineering. Each week for two decades I have created a new technology-themed crossword puzzle using only words (1,000s of them) from my custom-created lexicon related to engineering, science, mathematics, chemistry, physics, astronomy, etc. You will never find among the words names of politicians, mountain ranges, exotic foods or plants, movie stars, or anything of the sort. You might, however, find someone or something in the otherwise excluded list directly related to this puzzle's technology theme, such as Hedy Lamarr or the Bikini Atoll, respectively. Avid cruciverbalists amongst us: the gauntlet has been thrown down.

Frenzied Radio

"And there is nothing new under the sun." - Ecclesiastes 1:9, NKJV (did you know that is the origin of the saying?). This 1930 editorial by Radio-Craft editor Hugo Gernsback describes a coordinated scam perpetrated by radio manufacturers to compel consumers to buy new sets rather than have their existing sets repaired. In short, retail prices were inflated to accommodate a built-in 'trade-in' allowance that far exceeded the repair cost or used radio cost. Radio service shops were getting the short shrift because many people who might have otherwise elected to have repairs made would instead trade in the old set for a new one...

Television in Twelve Colors

It really wasn't all that long ago when most people worked on computers with Color Graphics Adapter (CGA) that had just 16 colors (4-bit pixels). In the late 1980s (wow, maybe it really was a long time ago), the luxury of a 256-color (8-bit pixels) Video Graphics Adapter (VGA) monitor and video card would cost you around $300 each. I recall seeing ads for "16 million color" displays by ViewSonic that ran north of a kilobuck. My first "real" monitor was bought in 1987 and was 4-bit monochrome. Televisions, as you know, began as black and white (actually a infinite number of gray levels between black and white). When TVs first arrived in people's homes, they were glad for any kind of display, but it wasn't long before marketing gurus convinced the masses that...

To Be, Or Not to Be [a Metal] - Kirt's Cogitations™ #374

As a multi-decade-long amateur astronomer, I have read countless articles written by astronomers who refer to all elements heavier than helium (#2 on the periodic table of the elements) as "metals." Ostensibly, the origin stems from early detection of heavy elements in stars, based on heliographic spectrum investigations, where iron - being the most abundant stable byproduct of supernova explosions - was most readily observed. I wondered if the "metals" nomenclature came from the next heaviest element, lithium (#3 in the periodic table), being a metal, thereby laying the foundation. Not so, claims AI, since lithium is very rare overall in the universe, and not readily observed. For clarity, I also procured the scientific distinction...

Mac's Radio Service Shop: Mac and Free Estimates

I usually learn something new with each episode of Mac's Radio Service Shop, but not necessarily related to electronics. Such is the case this time where after Mac gives Barney a quick lesson in how to determine a transformer's winding turns ratio when needing to create an impedance match circuit. He then, while discussing whether "free" repair estimates are truly free or of any real value at all, he uses the phrase "a horse on you." Maybe it is because I don't frequent bars that I had never heard that, but after a little research I now know it refers to a bar dice game called "'Horse." "A horse on you" is when you lose the final round of a 2-out-of-3 challenge. "A horse apiece" is when you and your opponent each win one round in a 2-out-of-3...

Superconductors in AI Data Centers

"Data centers for AI are turning the world of power generation on its head. There isn't enough power capacity on the grid to even come close to how much energy is needed for the number being built. And traditional transmission and distribution networks aren't efficient enough to take full advantage of all the power available. According to the U.S. Energy Information Administration, annual transmission and distribution losses average about 5%. The rate is much higher in some other parts of the world. Hence, hyperscalers such as Amazon Web Services, Google Cloud and Microsoft Azure are investigating every avenue to gain more power and raise efficiency. The potential virtues of high-temperature superconductors..."

The Coming Breakthrough in Thermoelectricity

Consumer grade thermoelectric coolers have been around for so long now that most people probably assume there is nothing wondrous about the discovery that makes them possible. I still marvel at the process that allows the application of a current through physical junction of two dissimilar metals (certain types) to produce a cooling effect rather than the I2R heating normally associated with conductors. This article from a scientist at Westinghouse Electric's research laboratories provides a nice introduction to the subject of thermoelectricity from both electric current generation based on the application of heat to a dissimilar metals junction, and the aforementioned cooling effect possible from passing a current...

Stereophonic FM Multiplex System

FM radio has been in the news fairly frequently in the last couple years as phone manufacturers and the National Association of Broadcasters lobby the FCC and politicians to mandate the inclusion of FM radio capability into every phone manufactured. In a ploy to exploit the gullibility and egos of said bureaucrats and pols, their primary argument that FM radio is a "first informer in times of crisis," assuming of course that people will miss news of "the big one" when and if it occurs. To my knowledge, successful reception of FM radio on a cellphone requires the listener wear a set of wired ear buds since the wire from the phone to the ear buds functions as the antenna. What percentage of cellphone users would bother to carry a set of ear buds? I, of course, am a huge proponent of...

Popular Electronics Crossword Puzzle

Arthur Brach created many crossword puzzles for Popular Electronics magazine in the 1950s and 1960s. Unlike the hundreds of RF Cafe Crossword Puzzles I designed over more than two decades, the PE puzzles usually have a few words that are not specifically related to electronics and/or technology. Still, they are a good source of a brief break from the day's business. You will need to print out this crossword puzzle to work it, since it is not interactive. Have fun.

Is Fair Trade the Answer to TV Price Cutting Problem?

"Fair Trade" was a policy established in the post-WWII era in response to what consumer retail groups considered business-ruining cost cutting by dealers who offered to sell products at or barely above cost in order to steal profit from other stores. So-scheming stores planned to make up for the low profit margin with high sales volumes. Doing so drove a lot of the local competition out of business, leaving the crafty dirty dealers to later raise prices. Stores that had manufacturer-sanctioned service shops often got screwed because they were obligated to repair items like TVs and radios that were bought from another dealer who did not do service work. Profit margins on repair work - at least from honest shops - were typically very low, so the owners depended on new product sales...

Quantum Teleportation: What's New

Yowza, yowza, yowza (The Jazz Singer), QentComm's stock will be rising soon! "Quantum technology is already alive and well in telecom networks, and although security is the top-of-mind use case, telcos are also looking at quantum to make networks more resilient and transmit information more quickly. Comcast announced this week it completed a trial with AMD and Classiq that leveraged quantum software to find independent backup paths for network sites. Elsewhere, Deutsche Telekom and Qunnect successfully demonstrated quantum teleportation over an existing fiber network in Berlin..."

Men Who Have Made Radio: Count Georg von Arco

The persona of Scott Adams' "Dilbert" is described exactly in the opening sentence of this article in a 1930 edition of Radio-Craft magazine. It is amazing - if not frustrating - to realize how long the perception of science-minded people being introverts has been around. Dilbert's "pointy-haired-boss" is nailed in the second sentence. Georg von Arco is celebrated here as a major contributor to the advancement of early radio, particularly wireless telegraphy equipment development. Interestingly, as brought to my attention by Melanie as she did the text clean-up after OCRing the magazine page, von Arco worked at the Sayville radio transmission station on Long Island, New York, where the Telefunken Company's Dr. K.G. Frank was arrested and interred for the duration of the World War I for sending out "unneutral messages...

Tune Your Antenna with a String

Lots of Hams still use this tried-and-true system for tuning antennas for efficient operation on a variety of bands. There are plenty of multi-band designs that rely on traps to reactively isolate portions of the antenna that properly resonate at the desired frequency, but there is usually a price to be paid in VSWR. Poor VSWR; i.e., higher mismatch loss, can be overcome with higher transmitter output power, but the real sacrifice for poor matching is loss of receiving range. The utter simplicity of using an insulated cord to vary the physical length of the antenna element(s) for tuning is hard to beat. It could be impractical on a setup where access to the antenna mount is difficult, but my guess is most people can make good use of it...

Russian Proposes Global TV

In this 1958 Popular Science magazine article titled "Russian Proposes Global TV," Soviet engineer V. Petrov proposed a global TV relay using three geosynchronous satellites at 35,800 km altitude, launched 120° apart from the equator at ~6,000 mph to match Earth's 24-hour rotation. Fixed over sites like the USSR, China, and USA, they would relay signals - uplink on meter waves, downlink on microwaves - via inter-satellite links, enabling worldwide broadcasts beyond line-of-sight limits with directional antennas mitigating solar interference. Each would require 10-kW antenna power, potentially reduced via pulsed transmission (note digital waveforms in the drawing). This closely mirrored Arthur C. Clarke's 1945 Wireless World article "Extra-Terrestrial Relays," which...

The "Stenode Radiostat" System

Frequency crowding has evidently been an issue since the early days of radio according to this 1930 article in Radio-Craft magazine. The situation was really bad in the earliest times when unfiltered spark type transmitters were the norm. Those pioneers could be credited, I suppose, with being the first users of wideband communications, but it was not because they chose to do so. Here author Clyde Fitch discusses the debate over whether there really were such things as sidebands from modulation and makes an argument for their existence based on analysis of various types of modulation. In particular, he predicts the coming popularity of single sideband receivers with crystal-filtered channels, and the need for matching SSB transmitters with... wait for it... carrier and sideband suppression...

140 GHz Wireless Transceiver Rivals Fiber

"A new transceiver developed by electrical engineers at the University of California, Irvine boosts radio frequencies into 140-gigahertz territory, unlocking data speeds that rival those of physical fiber-optic cables and laying the groundwork for a transition to 6G and FutureG data transmission protocols. To create the transceiver, researchers in UC Irvine's Samueli School of Engineering devised a unique architecture that blends digital and analog processing. The result is a silicon chip system, comprising both a transmitter and a receiver, that's capable of processing digital signals significantly faster..."

Rhombic Antennas for Television

Somehow, after being in the RF business for four decades, I have to admit to not being familiar with the term "acceptance angle" for antennas. That is after having read scores of articles on antennas. Maybe I did and just don't remember - embarrassing. Acceptance angle is mentioned and explained in this article during the description of rhombic antenna characteristics versus dipoles and multi-element designs. Although the author focuses on television installations, information provided on signal reflections, shadowing, ghosting, multipath, etc., is applicable to radio as well...

All About Electrolytic Condensers

Electrolytic capacitors have long been the components that provide the highest capacitance density factor, that is, they have the highest capacitance value for a given volume of space occupied. Anyone familiar with electrolytic capacitors is aware of the polarization indicated on the package (a marking or unique physical feature), indicating that there is required direction for hookup; in fact, a backwards connection can lead to an explosive failure. While physical construction of electrolytic capacitors have evolved over the decades since this article was published, the fundamental operation has not. It is interesting to note the reference to capacitors as "condensers," a name still commonly used with internal combustion engine ignition systems and with some AC motors that use them at turn-on for providing a starting coil phase shift...

Is Radio Earthbound?

This 1959 Popular Science magazine reprint of a 1925 Radio News magazine article focused is on visionary physicist Robert H. Goddard's proposed Moon Rocket as a means to test whether radio waves can traverse interstellar space, potentially enabling communication with other planets. Amid recent radio achievements, including mysterious signals during Mars' approach and solar disturbances recorded on Earth, the piece challenges Oliver Heaviside's theory that radio waves are confined by Earth's atmosphere. Goddard's innovative rocket, propelled by successive explosive charges to escape gravity and reach the Moon, would carry a compact radio transmitter in its nose cone, broadcasting signals throughout its flight. Astronomers would track...

RF & Microwave Engineering Crossword Puzzle

This week's crossword puzzle, as with all RF Cafe puzzles, uses only words pertaining to engineering, science, mathematics, mechanics, chemistry, astronomy, etc. You will never find a reference to some obscure geological feature or city, or be asked to recall the name of some numbnut movie star or fashion designer. You will, however, need to know the name of a famous RF filter design software author. Enjoy...

Flat Optical Surface Brakes Major Light Rule

"Broadband achromatic wavefront control plays a central role in next-generation photonic technologies, including full-color imaging and multi-spectral sensing. A research team led by Professor Yijun Feng and Professor Ke Chen at Nanjing University has now reported a significant advance in this field in PhotoniX. The researchers introduced a hybrid-phase cooperative dispersion-engineering approach that combines Aharonov-Anandan (AA) and Pancharatnam–Berry (PB) geometric phases within a single-layer metasurface. This strategy enables independent achromatic control of wavefronts for two different light spin states..."

Luigi Galvani - 200th Anniversary

As with the article in this month's issue of Radio-Craft magazine (December 1937), the reference to a 200th anniversary is understated by 88 years for 2025. Luigi Galvani was sort of the Benjamin Franklin of biology in that just as Franklin demonstrated that lightning was a form of electricity, Galvani showed that signals sent from the brains to the appendages of animals were electrical in nature. In my high school days in the 1970s, we duplicated his experiment by making deceased frogs' legs twitch when motivated by a D cell. Today, such an exercise would likely be met with demonstrations by animal rights people (whose lives, BTW, have probably in some way been improved as a result of previous such experiments). But, I digress. Mr. Galvani's name is...

The Superheterodyne Cycle

Superheterodyne receivers were originally the sole domain of the Radio Corporation of America (RCA), which owned the patents and refused to license them until around 1930. Hugo Gernsback, a contemporary editor of the era, provides a little insight into the superregenerative receiver circuits superheterodyne was about to replace, and why it was an important improvement in technology. Sidebar: The question often arises regarding the difference between a "heterodyne" circuit and a "superheterodyne" circuit. The most popular answer that "super" refers to the IF being located above the range of human hearing, which peaks at about 15 kHz. Doing so assured that any IF leakage into the audio circuits would not be discernable by a radio...

• FDA Clarifies Wearable Device Rules

• Revisiting the 1996 Telecommunications Act

• China's BeiDou Satellite (their GPS) Does Emergency Messaging

• How & When Will Memory Chip Shortage End?

• At Age 25, Wikipedia Refuses to Evolve

• Amazon Leo Asks FCC for Satellite Launch Extension

The RF Cafe Homepage Archive is a comprehensive collection of every item appearing daily on this website since 2008 - and many from earlier years. Many thousands of pages of unique content have been added since then.

Kennedy Superheterodyne Short-Wave Converter Radio Service Data Sheet

This Radio Service Data Sheet for the Kennedy Superheterodyne Short-Wave Converter (Model 54 "Globe Trotter") is an example of the dozens of similar schematic and alignment instruction sheets that have been posted on RF Cafe over the years. It appeared in a 1932 issue of Radio-Craft. Obtaining technical information on most things, even readily available items, prior to the Internet era was often very difficult - if not impossible. Service centers had what was need provided by manufacturers and distributors, but if you wanted to find a part number or service data on a refrigerator, radio, lawn mower, garage door opener, etc., and did not have the original paperwork, you were usually out of luck. Nowadays a Web search will quite often get you what you need thanks to people (like me) who go to the trouble of making the information available. The stuff doesn't just magically appear or get posted by benevolent governmental entities...

1940 Sears Amateur Radio & Test Equipment Catalog

RF Cave visitor and contributor Joseph Birsa (N3TTE), sent me a note about yet another edition of a special purpose catalog published by Sears - the Sears 1940 Amateur Radio, Test Equipment, Sound System Catalog. A little research revealed that it was actually an extended version of the 1940 Sears, Roebuck and Co. Superior Amateur Equipment and Radio Service Supplies - 64 versus 48 pages, respectively. Even the standard edition Sears, Roebuck Fall 1941 Catalog contained a large section dedicated to radios and equipment. The cover on the shorter catalog makes me think of The Radio Boys series of books, where a cadre of four early 20th century teenagers experienced adventures centered around building and operating wireless equipment. Hallicrafters, National Company, Meissner, and Hammarlund receivers and transmitters were offered for sale. Bliley and Silvertone...

How to Target RFCafe.com for Your Google Ads

One 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 225,000k per year (in eight locations on each page, with >17k pages)...

Standardized Wiring Diagram Symbols & Color Codes

When this Standardized Wiring Diagram Symbols & Color Codes feature appeared in a 1956 issue of Popular Electronics magazine, semiconductors were just coming into common use. Therefore, only the simplest components like a diode and bipolar junction transistor (BJT) are included. In fact, the only two types of diodes shown are vacuum tube and selenium. The semiconductor diode is labeled as a crystal rectifier. There is no light emitting diode (LED), field effect transistor (FET), metal oxide semiconductor FET (MOSFET), integrated circuit (IC), or other commonly used modern device. Note also that the "Receptacle 117V" does not show a safety ground connection. The "Vibrator" was a device commonly used to convert direct current (DC) to alternating current (AC). About the only people who will find a use for this information are those who service and/or restore vintage electronic equipment...

RF Engineering Theme Crossword for March 28th

This RF Engineering Theme Crossword Puzzle for March 28th has many words and clues related to RF, microwave, and mm-wave engineering, optics, mathematics, chemistry, physics, and other technical subjects. 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 (e.g., Reginald Denny or the Tunguska event in Siberia). The technically inclined cruciverbalists amongst us will appreciate the effort. Enjoy!

The Facsimile Receiver

The first facsimile (fax) machines for home use were receive only, and got their data not from the telephone line but from a commercial broadcast radio receiver. Radio Corporation of America (RCA) and Finch Telecommunications were two of the earliest entrants into the realm. As opposed to modern digital fax machines, these analog systems used a scanning raster light beam and a photodetector to read and encode the original document image, and then a complimentary scanning method on the receiving end literally burned the image into special thermal paper. The Radio Historian website has an excellent article covering the history of radio facsimile, and how its being was motivated by the newspaper industry fretting over market share being lost to commercial AM and FM radio...

Electronic Measurements Quiz

Popular Electronics' master quizmaster Robert P. Balin created this "Electronic Measurements Quiz" to test your ability to match the indicated component with one of the commonly associated parameter units. For instance, if a carbon resistor was illustrated, you would choose, if offered as an option, the temperature coefficient of resistance unit of ppm/°C. I erroneously swapped the units for item A and item H (80% score). Oh well, there goes the cumulative quiz GPA. Maybe you will do better...

Carl & Jerry: Going Up, Up, Up

Thanks to Mr. Ferrous Steinka for submitting this commentary on the episode of Carl & Jerry appearing in the March 1955 issue of Popular Electronics. "Radio and television waves are reflected in the same way as light waves. As both light and radio waves are forms of electromagnetic waves, they are both subject to the same basic laws and principles. Visual examples of light reflection are everywhere from specific mirrors to flat reflective surfaces like glass, polished metal and the like. So too, radio waves can experience reflection. Conducting media provide the optimum surfaces for reflecting radio waves. Metal surfaces, and other conducting areas provide the best reflections, so the story below is feasible and within the known technology at the time. The use of a highly directional Yagi antenna would have been very important because without it the reflected waves would have been inverted (out of phase) with the normal signals, thereby reducing the overall received signal..."

Radio Theme Crossword Puzzle for July 4th 

This Radio Theme Crossword Puzzle for July 4th has a few words paying homage to what remains of the freedoms and promises of America, along with words and clues related to RF, microwave, and mm-wave engineering, optics, mathematics, chemistry, physics, and other technical subjects. 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 (e.g., Reginald Denny or the Tunguska event in Siberia). The technically inclined cruciverbalists amongst us will appreciate the effort. Enjoy!

Basic Laser Experiments

Parenthetically mentioned in this introductory article on lasers is a "Mie" type particle. At first I thought maybe it was a typo, but in fact it refers to Mie scattering, which is the dispersion of electromagnetic waves by isolated spheres, stratified spheres, infinite cylinders, or other geometries where radial and angular dependence are independent. Two simple experiments are described for demonstrating light scattering and absorption similar to what occurs in the atmosphere. Whereas procuring the 2.5 mW laser source and to a lesser extent suitable light meter would have been difficult and expensive in 1971 when this was published in Radio-Electronics magazine, today's cheap equipment puts them within the budgets of almost anyone. Many of the <$10 cat toy lasers provide plenty of power...

Constructing PC Boards

Today if you need a printed circuit board (PCB) for prototyping, there is a good chance you will look up a quick-turn company like those found on the PCB Directory website like Bittelle, San Francisco Circuits, or a host of other providers. Costs can be a little as $40 to $50 for three, 3" x 3", 2-layer PCBs and can be delivered in a week or less. A 4-layer PCB of the same size would cost somewhere around $100. Considering how much circuitry can be squeezed into a 9 inch2 board these days, board with surface mounted components on both sides, that's a lot of board for a little money. If you are really in a hurry for your boards, the fabrication companies offer various levels of expedited service for more $$$. There are some people who for one reason or another still prefer to make their own PCBs. For them, this article from Popular Electronics magazine might be a good resource for how to go about it. All the necessary materials like ferric chloride and copper clad substrate material...

Smellevision Now Here!

We all know that for the most part television stinks. Back in 1951 when this article appeared in Radio-Electronics magazine, the technology was very new and it was considered a miracle not to be wasted on inane programming. Newscasts actually presented news and not opinion, movies and sitcoms cast the nuclear family, law enforcement, the military, religion, and patriotism in a positive light rather than as the purveyors of evil in the world. By the end of the 1960s to early 1970s a lot of that had changed. Political and social agendas weaseled their way into nearly all programming to the extent that terms like "boob tube" and even, yes, "smellivision," became common monikers for television. The form of smellivision presented in this article was granted patent (US2540144A) protection in 1951 under the title, Television with scent effects..."

Holes and the Service Technician

It is understandable if, based on this article's title, "Holes and the Service Technician," you thought maybe it had to do with semiconductors. Silicon was beginning to overtake germanium as the substrate of choice it appeared in a 1963 issue of Radio-Electronics magazine. Electron conduction seemed intuitive to most people involved in electronics; however, the concept of hole conduction caused a lot of head scratching. But, I digress. This article discusses how to create various types of holes in metal. It might seem like a no-brainer task, if you have ever needed to make precisely shaped and dimensioned holes in metal, you know it is not always such a simple task - especially in soft sheet metal. Achieving a truly round hole - especially of large diameter - in an aluminum chassis requires securely clamping the work piece to the table and using a sturdy drill press. Otherwise, you almost always get an oblong hole. A machinist at Westinghouse showed me one day back in the 1980's how he would get the chassis secured and drill press positioned, then place a couple layers of paper towel on the metal before lowering the drill bit onto the chassis. It helped fill the space between drill bit flutes to prevent it from "walking" before both sides of the bit had a bite on the metal. It works like magic, even when using a hand drill. To this day I still do that...