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HF antennas. Schemes, articles, descriptions

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HF antennas

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Homemade wind turbine. Springs

Section Alternative energy sources. The spring 20 is made of steel wire. In table. 1 shows the data for the spring with different diameters of the wire from which it can be made. Since each spring, when removed from the mandrel, slightly increases the diameter of its coil, the size of the mandrel in Table. 1 is shown only approximately. To accurately determine the required diameter of the mandrel, it is necessary to wind several turns of wire, remove them on the mandrel, measure the diameter of the spring coil and, as a result of measurement, slightly increase or decrease the thickness of the mandrel. It is desirable that the discrepancy between the required and manufactured diameters of the spring coil does not exceed 1 mm. ... >>

Economical narrowband FM receiver

Section Radio reception. In amateur radio communications and in portable communication radio stations in the range of 27,120 ... .27,250 MHz, it is allowed to use narrow-band FM with a deviation of 4-3 kHz. In this case, it is possible to use simple VXO transmitters with an output stage in class C, having a high and constant efficiency. up to 70%. However, the use of this type of modulation is hampered by the fact that FM receivers made on a traditional element base are more complicated than AM and SSB receivers and consume a fairly large current of 20-40 mA, which makes it impossible for long-term battery power, for example, in standby mode. ... >>

wow booster for electric guitar

Section Electronics - musician. The described device allows you to implement wah-wah effects. soft attack, booster (click) and wow-booster in the sound of electric guitars of all varieties. It practically does not require adjustment, it is in good agreement with guitar pickups of various types (input signal level 10 ... 100 mV), it has a simple system for switching operating modes. It should be noted that when operating in the Booster and Wah-Booster modes, it performs the functions of a dynamic noise level limiter and prevents the occurrence of excitation due to acoustic feedback in pauses, even when phae and distortion devices are connected to the input ... >>

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Articles on HF antennas

Articles on HF antennas; HF antenna circuits; descriptions of HF antennas: 170 articles



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Latest news of science and technology, new electronics:

Blinking of the magician and his audience 19.05.2024

Magic and illusions have always captured the attention of the public, but what happens behind the scenes of the magician and in the brains of his audience? Scientists from the UK decided to solve this mystery by conducting a new study involving ten illusionists of varying experience. Illusionists, some of whom had been practicing magic for more than half a century, others for only six months, were invited to demonstrate the same trick - the popular coin trick. Recordings of their performances during training and on stage showed that each of them began to blink significantly more often at the moment of performing the trick. The study's findings indicate that magicians' blink rate may be related to unconscious aspects of their performance. At the same time, as scientists have found, spectators also begin to blink more often, following the movements of the illusionist. This observation supports the idea that magicians may be catalysts for blinking in audiences. Additional research has shown that magicians blink more often during ... >>

Ultrasonic coffee machine 19.05.2024

Iced coffee has become an integral part of coffee culture in recent years. Therefore, engineers from the University of New South Wales decided to improve its preparation. They have developed an ultrasonic coffee machine that reduces the cold brew time for ground coffee beans from 12-24 hours to significantly less time. Iced coffee, or "Cold brew", is popular due to its smoothness, low acidity and low bitterness. It is prepared by steeping ground coffee in cold water for a long time. Unlike traditional hot brewing, which often imparts bitterness to coffee, cold brewing extracts more delicate and complex flavors from the coffee beans. The innovative system, presented by a team of engineers, introduces ultrasonic technology into the coffee preparation process. The system uses ultrasonic waves to speed up the process of extracting oils, flavor and aroma from ground coffee. This allows you to significantly reduce the time ... >>

The speech of sperm whales is similar to that of humans 18.05.2024

In the world of the ocean, where the mysterious and unknown coexists with the studied, sperm whales, with their huge brains, are of particular interest to science. Researchers, working with a huge array of audio recordings collected during the Dominica Sperm Whale Project (DSWP) - more than 8000 recordings, seek to unravel the secrets of their communication and understand the structure and complexity of the language of these mysterious creatures. By studying in detail the recordings of 60 sperm whales in the eastern Caribbean, scientists have revealed surprising features of their communication, revealing the complexity of their language. "Our observations indicate that these whales have a highly developed combinatorial communication system, including rubato and ornaments, which indicates their ability to quickly adapt and vary during communication. Despite significant differences in evolution, sperm whales have elements in their communication that are characteristic of human communication," says Shane Gero, a biologist at Carleton University and director of the CETI project. Issl ... >>

Random news from the Archive

Moonshine instead of gasoline 11.05.2009

The American company "E-Fuel" entered the market with a moonshine, designed to produce ethyl alcohol from sugar, to replace gasoline in a car with alcohol.

Buyers are offered a device the size of a large refrigerator, which produces up to 132 liters of alcohol per week, and this fuel will cost two to three times cheaper than gasoline. In addition to sugar, distillation, brewing and fruit processing wastes are suitable as raw materials. The firm hopes to sell up to 200 of these units.

Critics of the idea point out that sugar is too expensive, and the car engine will have to be significantly altered for pure alcohol. However, the manufacturer claims that cheap sugar can be imported duty-free from Mexico, where it is overproduced, and the waste of winemakers and brewers is generally free.

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