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TCXO, Temperature Compensated Crystal Oscillator

Descripción: TCXO, Temperature Compensated Crystal Oscillator As the name indicated a temperature compensated crystal oscillator provides a means of counteracting the frequency change caused by temperature change in a crystal oscillator. The letters TCXO stand for Temperature Compensated Xtal Oscillator - Xtal is short from crystal and implies a quartz crystal resonator. The TCXO module is able to provide considerably improved performance over that of a standard crystal oscillator, especially in terms of frequency stability over a temperature range. By measuring the temperature and applying a correction voltage to a VCXO, the frequency stability over a temperature range is considerably improved whilst keeping costs low - using an oven controlled crystal oscillator, OCXO would be considerably more costly and much larger in size. Often a wide range of TCXOs of varying frequencies, supply voltages and packages is available from many distributors, enabling these electronic components or modules to be used in many general electronic designs, RF circuit designs, etc. Temperature performance of crystal oscillator Crystal oscillators are able to provide a much better level of performance than that provided by LC resonator circuits. Nevertheless crystal oscillators are still affected by temperature. The angle of the cut and other aspects of the quartz crystal have a major impact on the performance. As a result special cuts are defined and one known as the AT cut is the most widely used for these and many other quartz crystal RF applications. This gives a good level of performance for RF circuits in terms of suppression of unwanted modes of vibration as well as the frequency range available, and also the temperature stability. Despite this, AT cut crystals on their own cannot meet the requirements for many applications and temperature compensation is required if they are to perform satisfactorily over the required range - often 1 - 70°C at elast is needed. The effects of temperature are, to a large degree, repeatable and definable. Therefore it is possible to have an electronic design to compensate for this. By adding additional electronic components to the basic oscillator, it is possible to considerably reduce the effects caused by temperature changes: a temperature compensated crystal oscillator, TCXO. TCXO solution A TCXO adjusts the frequency of the oscillator to compensate for the changes that will occur as a result of temperature changes. To achieve this, the main element within a TCXO is a Voltage Controlled Crystal Oscillator, VCXO. This is connected to a circuit that senses the temperature and applies a small correction voltage to the oscillator as shown below. INTRODUCTION The history of the development in crystal filter technology, from the initial concepts of Cady to the current wide range of products, provides a fascinating chapter in the development of today’s highly complex electronic products. The crystal filter has been a particularly critical element in the development of narrowband communications systems. The desire to send multiple voice messages on a single telephone line resulted in the introduction of carrier telephone systems in 1916. These early systems used LC filters in the 10 to 40 kHz frequency range. However, the bandwidth limitations caused by realizable coil Q’s were quickly recognized. In 1929, W.P. Mason of Bell Laboratories developed methods for incorporating crystals into LC lattice filter networks. This work resulted in the development of a 60 to 108 kHz basic group-band filter set used to frequency multiplex 12 voice channels. This work is described in Mason’s 1934 paper which was the basis for essentially all crystal filter designs generated during the next 20 years. During this period the major application for crystal filters was in carrier telephone equipment. However, in the mid-1950s, newer narrowband radio communications systems were developed both for military and commercial use which required high-frequency, stable, narrow-bandwidth filters. In most cases, crystal filters were the answer for these filtering applications and a new manufacturing industry was formed to supply these needs. Other applications quickly followed in navigation and radar equipment, in new fire-control systems, and missile control systems. This increased level of activity resulted in new filter design procedures and substantial improvement in the quality of high-frequency filter crystals. In the 1960s another major technology step occurred with the development of monolithic crystal filters. Through the 1970s and ’80s evolutionary improvements were made with the development of multi-pole monolithic filters and the extension of the high frequency limits through continued process improvements. Significant theoretical work was also accomplished in this period in the area of device modeling. High frequency limits are still being pushed today with blank etching techniques and improved photo-lithography. DESIGN EVOLUTION Professor Walter Cady, who carried out much of the original development work on quartz crystals, was apparently the first to suggest the use of crystals as filter elements. In his 1922 paper he shows single-mode crystals with divided electrodes which could be used as coupling elements between adjacent circuits. However, in this configuration, only very narrow bandwidths are achievable and the filter would be useful only as a carrier-frequency filter. In 1927 patent disclosures were filed by L. Espenschied of AT&T and C. Hansell of RCA on the use of crystals in a filter structure. The Espenschied patent shows the use of crystals in a ladder filter structure in a variety of configurations. He also shows the use of inductors in series or in shunt with the crystals to widen the filter bandwidth. In Hansell’s patent the use of a bridge circuit is shown using all capacitors or a center-tapped transformer to balance out the crystal shunt capacitance. This is essentially the hybrid-lattice configuration which is commonly used in discrete crystal filters. He also proposed a method for widening the bandwidth by placing several crystals with slightly different frequencies in parallel. The challenge of providing filters with useful bandwidths was apparent from the earliest days and many techniques (usually unsuccessful, including Hansell’s) were attempted. In his patent Hansell makes the interesting observation that “The crystal filter has the advantage of being so sharply selective that the necessity for more than a single section probably will never arise.” Ceramic Filtration Locally manufactured ceramic filters have traditionally been used throughout the world to treat household water. Currently, the most widely implemented ceramic filter is the Potters for Peace design. The filter is flowerpot shaped, holds about 8-10 liters of water, and sits inside a plastic or ceramic receptacle. To use the ceramic filters, families fill the top receptacle or the ceramic filter itself with water, which flows through the ceramic filter or filters into a storage receptacle. The treated water is then accessed via a spigot embedded within the water storage receptacle. The filters are produced locally at ceramics facilities, and then impregnated with colloidal silver to ensure complete removal of bacteria in treated water and to prevent growth of bacteria within the filter itself. Numerous other locally-made and commercial ceramic filters are widely available in developed and developing countries. The filter is flowerpot shaped, holds about 8-10 liters of water, and sits inside a plastic or ceramic receptacle. To use the ceramic filters, families fill the top receptacle or the ceramic filter itself with water, which flows through the ceramic filter or filters into a storage receptacle. The treated water is then accessed via a spigot embedded within the water storage receptacle. The filters are produced locally at ceramics facilities, and then impregnated with colloidal silver to ensure complete removal of bacteria in treated water and to prevent growth of bacteria within the filter itself. Numerous other locally-made and commercial ceramic filters are widely available in developed and developing countries. Lab Effectiveness, Field Effectiveness, and Health Impact The effectiveness of ceramic filters at removing bacteria, viruses, and protozoa depends on the production quality of the ceramic filter. Most ceramic filters are effective at removing bacteria and the larger protozoans, but not at removing the viruses. Studies have shown adequate removal of bacterial pathogens in water filtered through high quality locally-produced or imported ceramic filters in developing countries. A 60-70% reduction in diarrheal disease incidence has been documented in users of these filters. Studies have also shown significant bacterial contamination when poor-quality locally produced filters are used, or when the receptacle is contaminated at the household level. Because there is no chlorine residual protection, it is important that users be trained to properly care for and maintain the ceramic filter and receptacle. What Is a Ceramic Resonator? A ceramic resonator is an electric component that exhibits a series resonant and a parallel resonant center frequency. It exhibits a piezoelectric characteristic that makes the ceramic material generate minute electrical energy when subjected to electromechanical expansion and compression. The resulting mechanical energy component produces the electric component and vice versa, and the result is a complex reactance that leads to resonance observed as the characteristic of having a center frequency. Materials such as lead zirconium titanate have a ceramic piezoelectric characteristic. Oscillators are electronic circuits that generate periodic waveforms. The ceramic resonator may be used as a frequency reference in the electronic oscillator, wherein the accuracy of the resulting frequency is not as high as in the crystal oscillator. Error in frequency for the ceramic resonator circuit may be as high as 5%, while that for the crystal oscillator is less than 0.1%. The ceramic resonator may also be used for intermediate frequency (IF) amplifier stages, which are found in heterodyne radio receivers that derive a common IF to receive a sub-band of frequencies. For instance, a radio receiver tuned to 1,000 kilohertz (kHz) or 1,000 cycles per second may generate a local oscillator frequency of 1,455 kHz so that the difference is 455 kHz, which is a typical IF frequency. To receive a 1,500 kHz signal, the local oscillator is tuned to 1,955 kHz and the resulting difference is still 455 kHz. This ceramic resonator is tuned or cut to resonate at around 455 kHz and will serve a sub-band like 550 to 1,600 kHz as in a typical amplitude modulation (AM) band. A typical ceramic resonator has three terminals. The two main terminals are at each wide side of a thin ceramic material, while the middle terminal is usually connected to the thin side and may be grounded or used to tap signal into the rest of the oscillator circuit. There are, however, ceramic resonators as well as crystal resonators with only two terminals. Amplifiers are the active parts of the oscillator. The ratio of the output voltage to the input voltage of an amplifier is known as the voltage gain, which is dependent on the frequency of interest. Very few amplifiers will maintain a constant gain over a wide range of frequency. When a ceramic resonator controls the oscillator frequency, the voltage gain at the ceramic resonator frequency has to be greater than 1. If the voltage gain is less than 1, the amplifier will not start oscillating. In electronics, design amplifiers and oscillators have very common components. With design shortcomings, some amplifiers can be very close to oscillating. Meanwhile, some oscillators may just stop oscillating and behave like idle amplifiers. Ideally, amplifiers do not have output when there is no input signal.

Fecha de Publicación: 11-10-21

Benefits of using a humidifier

Descripción: Benefits of using a humidifier Humidifier adds moisture to the air, which can benefit people with respiratory symptoms or dry skin. There are several ways to use humidifiers in the home or office, but there are also some risks. In this article, learn about the benefits of humidifiers, how to use them correctly, and precautions to take. Dryness and humidity By adding moisture to the air, humidifiers may be beneficial for several medical conditions. Dry air can cause moisture to evaporate from the skin and respiratory symptoms to worsen over time. Adding moisture to the air with a humidifier can counteract these problems. Humidifiers can help people who experience: dry skin irritated eyes dryness in the throat or airways allergies frequent coughs bloody noses sinus headaches cracked lips Five humidifier uses and their benefits Some people experience respiratory symptoms in the summer months, when the weather is hot, and the air contains more allergens. Air conditioners and fans can circulate dry air through the room, and air conditioners remove any moisture from the air. A humidifier may be beneficial during this season. However, people are more likely to benefit from a humidifier in the cold months, when cold air dries out the lungs, nose, and lips. Also, some types of central heating can dry out the air indoors. Benefits of a humidifier may include: 1. Preventing influenza Authors of one studyTrusted Source noted that humidifiers might reduce the risk of catching the flu. After adding the influenza virus to the air with a simulated cough, researchers found that humidity levels above 40 percent rapidly deactivated virus particles, making them much less likely to be infectious. 2. Making a cough more productive Dry air can cause a person to have a dry, unproductive cough. Adding humidity to the air can get more moisture into the airways, which can make a cough more productive. A productive cough releases trapped or sticky phlegm. 3. Reducing snoring Increasing the amount of moisture in the air can also reduce snoring. If the air is dry, a person’s airways are less likely to be sufficiently lubricated, which can make snoring worse. Adding humidity to the air by running a humidifier at night may help to relieve some symptoms. 4. Keeping the skin and hair moist Some people notice that their skin, lips, and hair become dry and fragile in the winter. Many types of heating units pump hot, dry air through the house or office, which can make the skin dry, itchy, or flaky. Cold air outside can also dry out the skin. Using a humidifier to add moisture to the indoor air may help to reduce the occurrence of dry, cracked skin. 5. Benefits for the home Moisture from a humidifier can be helpful around the home. Any moisture-loving houseplants may become more vibrant, and wood floors or furniture may last longer. Humidity can also help to prevent wallpaper from cracking and static electricity from building up. Humid air can also feel warmer than dry air, which could help a person to save money on utility bills in winter months. Types of humidifiers While most humidifiers have the same basic function, to add moisture to the air, many types are available: Steam vaporizers: These use electricity to create steam, which cools before it leaves the unit. However, there is a risk of burning the skin, and people should avoid using steam vaporizers around children. Ultrasonic humidifier: Instead of electricity, these units use vibrations to vaporize water. Evaporators: These produce humidity by blowing air past evaporating water. Impeller humidifiers: These are generally child-friendly and use rotating disks, rather than heat, to vaporize water. Central humidifiers: A person connects one of these units to the central air conditioning in the home or office to add moisture to the entire space. Sizes can vary. Console humidifiers are large enough to add moisture to an entire house or office, while personal humidifiers are portable and easy to carry. What is an Industrial Humidifier? An industrial humidifier is a system that is capable of providing adequate humidity levels in a manufacturing environment. High-speed production processes add to the heat load in a building, bringing down the humidity. This can lead to a dangerous buildup of static electricity in a plant where dust and other flammable materials may be in the air. Processes such as woodworking, printing, and electronic and microchip fabrication, — which involve gluing, coating, and bonding — benefit from humidity control. Energy efficiency is also a consideration with an industrial humidifier. Related products include industrial steam humidifiers, as well as electric-powered and gas-fired models. Steam heat exchangers use a heat source for producing steam from tap water or pure water reserves. These are also designed to comply with indoor air quality requirements to ensure proper humidity levels along with clean air for workers. Industrial humidifiers are also designed as fog systems that integrate with building automation systems. In this configuration, an industrial humidifier system can be integrated above the factory floor, with the moisture released via fog nozzles. This is a viable alternative to humidifying air traveling through ducts, because excessive heat loads can be managed at the source. An industrial humidifier also can be a contamination control system. It can be capable of utilizing adiabatic humidification to control humidity and airborne particles, and reduce the buildup of electrostatic discharge that, when combined with particulates, can be a health hazard and a cause for major industrial accidents. Along with proper treatment of supply water, an industrial humidification system ensures a safe environment in which to work. An industrial humidifier can be found in many manufacturing facilities. Plants that make electronic assemblies require humidification, because the air in buildings producing circuit boards and computer equipment must be free of particles. Semiconductor manufacturing is another major application, because integrated circuit printing requires tightly controlled temperatures, along with a relative humidity (RH) of around 35 percent to 45 percent with acceptable tolerances within a range of 1/2 percent to 5 percent RH. What Does a Dehumidifier Do? A dehumidifier is an appliance that takes moisture out of the air in your home. If you or your family members have asthma or allergies, a dehumidifier might help relieve symptoms and make breathing easier. This article will help you decide whether a dehumidifier is a worthwhile investment for your living space. Dehumidifier uses and health benefits You may remember the water cycle from elementary school science: evaporation, condensation, and precipitation. What you might not realize is that the water cycle is always taking place in the air you’re breathing, even when you’re spending time inside. “Humidity” is a measure of water vapor in the air. Dehumidifiers remove or minimize this water vapor. How a dehumidifier works A dehumidifier works by drawing warm air currents into its coils via a fan. The warm air contracts as it’s fed through the refrigerated coils of the machine, and condensation is left inside the dehumidifier. As this condensation collects, one droplet of water at a time, it falls into a storage tank attached to the dehumidifier. Cooler, drier air is then released back into your home through the other side of the machine. Your dehumidifier should be able to bring the moisture in the air down to a relative humidity of 30 to 50 percent. Many dehumidifiers come with a meter that measures the relative humidity where it’s placed in your home, and you can set the humidity to the percentage you desire. Application of Dehumidifiers for Various Industries Food Industry: Excess humidity causes condensation and a broad range of hygiene problems in the product. Be it powdered food, spices, processed meat, snack foods confectionery products or breweries, consistent and controlled moisture conditions are necessary. Using dry air from a Desiccant dehumidifier can help in controlling the moisture content, which leads to perfect coating and longer shelf life of the food products. Lithium Batteries: The primary requirement for manufacturing of lithium batteries is a dry room with very low humidity. Lithium is extremely sensitive to moisture; thus, high moisture content leads to a reduction in performance and life of the product. Industrial dehumidifier ensures that the processing areas have the required amount of moisture in the air which is less than 14gms of moisture per kg of dry air. Pharmaceutical Industry: During the processing stage, most of the medicines are in powdered form and are highly hygroscopic. Excess of moisture absorption leads to organic corrosion, biochemical reactions and micro-organism growth on the product. Dehumidifiers help in keeping the required humidity parameters for processing, drying, storing and transportation of medicines. Cold Stores: To prevent flowers, vegetables, fruits, milk and processed foods from deterioration they are cooled and stored in cold store under low moisture conditions. Since the cold stores experience the frequent movement of products, warm air with moisture from outside could enter the store. This results in ice and frost formation on the walls, floors and ceilings on the cold stores. Air curtain using Dehumidified air at the cold store doors helps in controlling the ingress of moisture laden entering the cold rooms. Defense Industry: Military equipment is highly prone to humidity damage when they are stored for long periods. Uncontrolled humidity causes corrosion and malfunctioning of equipment, fungal growth on maps, drawings and bacterial infection on rations. Storage rooms of standard equipment such as trucks, tanks, guns and ammunition require specific humidity levels and controlled temperature. Dehumidifiers help in preventing corrosion on the equipment by keeping humidity levels less than 35%. Electronic and Semiconductors: Components used in assembling or processing of semiconductors are hygroscopic and highly sensitive to excess humidity. Excess moisture results in corrosion of PCB, transistor failures, and condensation on integrated circuits. The RH in semiconductor manufacturing area must be 30% at 20oc. Industrial dehumidifiers also help in protecting the vacuum and EPI equipment. Turbine Industry: Moisture can corrode turbines, boilers, condensers and many other machines when they are kept for maintenance during the layup process. High humidity causes corrosion and rusting on the equipment leading to their malfunctioning. As the repair and downtime costs of these equipment are very high, moisture control becomes essential. Industrial dehumidifiers help in keeping moisture levels low during the storage of the product; thus, preventing corrosion. Leather industry: The Leather is a hygroscopic material; excess moisture leads to the growth of mold and mildew on leather. Without proper humidity control, leather loses its shine, produces the foul smell, loses its strength and starts decomposing. Relative humidity above 40% leads to micro-organism growth that results in decomposition of leather. Dehumidifiers help in providing controlled moisture conditions during the processing of leather products. Ultrasonic Mist Maker I needed a simple mist maker/humidifier for a project that I was working on. I found lots of ideas on the internet, but they all lacked in one area or another, so I decided to design one. The following lays out my easy-to-build ultrasonic mist maker. It works fine and is, by far, the easiest ultrasonic mist maker/humidifier that I’ve ever had to get going. The misty head In an ultrasonic mist maker/humidifier (also called an ultrasonic atomizer), a piezo atomizer disc/transducer (ceramic humidifier) works by transposing high-frequency sound waves into mechanical energy that is transferred into a liquid, creating standing waves. As the liquid exits the atomizing surface of the disc, it’s broken into a fine mist of uniform micron-sized droplets, so the key component required for this little project is a particular (20-mm, 113-kHz) ultrasonic atomizer disc/transducer (see below). When buying the transducer, make sure that is has a 113-kHz (±3 kHz) resonance frequency — another popular transducer has a 1.65-MHz (±0.05 MHz) resonance frequency, which is not compatible with this project! Circuit diagram of the transducer driver Below is the circuit diagram of the final part of the project — the transducer driver. As shown in the circuit diagram, it’s a tricky oscillator design based on the ubiquitous tiny time chip NE555P (IC1) to generate proper drive pulse train for the atomizer transducer. In the circuit, the 5K multiturn trimpot (RP1) can be used to set the oscillator frequency to 113 kHz (±5 kHz) (TP1). Even though the ultrasonic mist maker device is configured to run on a single 5-Vdc to 12-Vdc input, this transducer driver needs a 20-Vdc to 26-Vdc (V_DRIVE) power supply channel in addition to a 5-V regulated DC supply rail. So a dedicated power supply circuitry will be introduced later to fulfill that crucial requirement.

Fecha de Publicación: 11-10-21

Are Hoverboards Dangerous?

Descripción: Are Hoverboards Dangerous? When hoverboards hit the scene in 2015, they were an immediate success. Also known as self-balancing or two-wheeled boards, these toys can be a fun way to get around. However, many parents began to wonder — just how dangerous are hoverboards? Shortly after their debut, several manufacturers started selling hoverboard that were not inspected for quality or safety. News reports revealed potential hoverboard dangers — motorized boards spontaneously overheating, catching fire and causing burns. To date, more than 300 of these incidents have been reported to the Consumer Product Safety Commission. Newer hoverboards don’t pose the same level of fire risk. If you have an older model, visit the Consumer Product Safety Commission to see if there’s been a recall. All hoverboards should be compliant with the UL 2272 safety standard. However, even if your child has one of the newest models, there are still hoverboard dangers to consider. After all, two-wheeled boards can be difficult to balance on, and falls resulting in injuries are not at all uncommon. A Look at Hoverboard Injury Statistics How often does a fall result in a serious hoverboard injury? Statistics from the American Academy of Pediatrics study show that about 26,854 children visited an emergency department with a hoverboard injury during 2015 and 2016. The average age of an injured child was 11, with boys being slightly more common than girls (52 percent of the children seen were boys). Children were most likely to injure their wrists, forearms and heads. The most common injuries were: Fractures (40 percent) Bruises (17 percent) Strains/sprains (13 percent) While these hoverboard injury statistics may seem alarming, many other wheeled toys — that have been around much longer — result in trips to the emergency room as well. During the same 2015 to 2016 time period, skateboards caused almost 121,400 injuries. How Does a Hoverboard Work? Do you ever daydream about the future? What might the world be like in a few decades? Could there be cars without drivers? Trucks that fly? Boats driving on land and water? You may already know about self-driving cars and self balancing hoverboard. But what about hoverboards? Picture it: You’re flying down the sidewalk on an object that looks like a skateboard without wheels. You turn a corner, swerve around other people, and get home from school in record time, without ever touching the ground! Does this sound like science fiction? Think again! Hoverboards are already a reality. But how do they work? The “hoverboards” you may have seen friends riding are actually self-balancing scooters. These scooters don’t hover above the ground. Instead, they use two wheels to get around. Okay, so why are they called HOVERboards? People call self-balancing scooters “hoverboards” because of the sensors that help them stay balanced. The board’s sensors find out which way the rider is leaning. They then tell the board’s motor how fast and in what direction to spin. That’s how this “hoverboard” stays balanced! Self-balancing scooters rely on a battery pack for power, and each one contains a logic board. You can think of this as the “brain” of the hoverboard. It processes things like the speed of the board and the tilt of its wheels. The logic board also manages settings. For example, hoverboards can be put in beginner mode to limit their maximum speed. If you’re not satisfied with a self-balancing scooter, have no fear! Hoverboards with no wheels are coming soon—and they’ll truly float above the ground. Some of these hoverboards may use the science of magnets. They will have hover engines that contain electrically charged magnets, or electromagnets. These use an inductor to create a powerful magnetic field. When the magnetic field is strong enough, the board will float in the air! A company called Omni has also created a hoverboard that uses propellers. Their design even holds the Guinness World Record for the farthest flight by hoverboard. It traveled 275.9 meters (905.2 feet). The Omni hoverboard is expected to hit the shelves in late-2021. Would you like to travel by hoverboard? Do you see a future of these vehicles zooming through the streets? Or do you imagine even better ways of getting around? Anything is possible! What is an all terrain hoverboard? These are similar to the original hoverboards in how they work, but they are generally bigger, stronger and more durable. Instead of being a traditional 6.5 inch hoverboard, most have 8.5 or 10 inch wheels. Instead of solid rubber tires (which are only suitable for smooth ground) they have pneumatic tires for travelling safely and smoothly over a variety of terrains including grass, gravel and sand for a more exciting riding experience. This makes them far more versatile and more fun because you can use them almost anywhere. Most all terrain hoverboards even come with builtin bluetooth hoverboard capability AND they’re suitable for kids and adults of all ages! https://ir-na.amazon-adsystem.com/e/ir?t=electricridessg-20&l=li3&o=1&a=B01MF6DO6NBack in 2015 hoverboards hit the market with a bang. These two wheeled self balancing scooters became THE hot product of the year, and although they hit a few blips along the way (inferior quality models with cheap batteries caused some fire problems in the early days), they have only gone from strength to strength since then. In 2016 Underwriter Laboratories introduced the UL 2272 hoverboard certification, so hoverboards are now safer and higher quality than ever. In 2021 technology has advanced to the stage where we now have all terrain hoverboards that can travel over grass, sand, gravel and more (the traditional hoverboards that first came on the market were only suitable for smooth pavement). In this article I’m going to be discussing which is the best off road hoverboard available today. Hoverboard? Still in the Future The hoverboard is fiction, the vision of screenwriters who created the film about Marty McFly, a teenager who travels from 1985 to Oct. 21, 2015, and uses a floating skateboard to flee a gang of bullies. The movie had other futuristic items, like flying cars and self-tying shoes, but none touched the imagination as much as the hoverboard. For the last 25 years, garage tinkerers, physics professors and top engineers at Google have been trying to make one. Inside a drab office park here in Northern California, Greg and Jill Henderson are working on the latest effort. On a recent visit the couple allowed a reporter to stand atop a noisy magnetic skateboard that can float above a copper surface. It hovers about an inch above the ground. But when the 190-pound visitor stood atop the 100-pound board, one gentle push was enough to send him spinning across the room over a cushion of air. The Hendersons have poured their life savings into hover technology and are hoping to create new industries based on this science. Dustin Rubio, 39, an electrician who grew up skateboarding and saw “Back to the Future Part II” when he was a teenager, is not thinking quite that big. This year, Mr. Rubio turned “a leaf blower, some plywood, some plastic and duct tape” into a small hovercraft that his daughters used to glide down the driveway at his home in Napa, Calif. “I was like I’m just gonna make something funny and see if it works,” he said. Unfortunately, his invention is not really a new hoverboard. Bob Gale, who wrote the “Back to the Future” trilogy, said that, in his imagination anyway, the hoverboard floats on a magnetic field similar to magnetic levitation trains.Continue reading the main story This has been extremely difficult, mostly because of something called Earnshaw’s theorem, which states, more or less, that repelling magnets are tough to balance. One way is to use a track that would hold the magnetic skateboard in place, but what self-respecting skateboarder wants to be constrained to a track? Superconductors can also levitate things. In 2011, a research group directed by Alain Sacuto, a physics professor at the Université Paris Diderot, used smoking-cold superconductors to levitate a liquid-nitrogen-filled skateboard that he and others rode across a five-meter magnetic rail. In March, the website Funny or Die released a video that seemed to show the skateboarder Tony Hawk on a real hoverboard. Mr. Hawk later apologized for misleading fans. “As early as this morning I had three emails from people: Is this real? Can I buy it?” Rachel Goldenberg, who produced the video, said on Monday. If you had to time-travel back to 1989 and place a couple of bets on who might invent the hoverboard, Rich DeVaul would have been a good wager. Mr. DeVaul is a senior engineer at Google X, the company’s research division. He is also a longboard skater and a snowboarder.

Fecha de Publicación: 11-10-21

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