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Filters and matching devices. Schemes, articles, descriptions

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Filters and matching devices

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QRP transceiver on 80m

Section Civil radio communications. This transceiver is designed to operate as a telegraph in the amateur band of 80 m. A quartz-frequency stabilized oscillator assembled on a VT5 field-effect transistor (see figure) is used both in the receiving and transmitting paths and performs, respectively, the functions of either a local oscillator or a master oscillator. The quartz resonator is connected to the XS4 socket. Within small limits (depending on the parameters of the resonator and the elements of the circuit L1C12), the operating frequency of the generator can be changed by a variable capacitor C12. Usually it is not difficult to shift the generator frequency by 2 ... 3 kHz ... >>

Security of the apartment with notification by telephone line

Section Security devices and signaling of objects. It is known that not all citizens who decide to install an alarm in their apartment can afford to use the help of specialized security companies. The author of the proposed article has developed a device that allows you to acquire a security system without resorting to their services. The described security device uses a chain of normally closed sensors connected in series. When any of them is opened, it automatically dials a predetermined telephone number an infinite number of times and gives specific sound signals. The subscriber at the other end of the wire, having understood the meaning of these signals, can return the device to standby mode by issuing a command with a DTMF signal, and take care of eliminating the threat to the protected object. A significant drawback of such a device is the need to take special measures to protect the telephone line, since if an intruder cuts the line, it will be neutralized. But more on that at the end of the article. ... >>

Stabilized DC motor speed controller

Section Electric motors. The circuit is designed to regulate and maintain a stable speed of a low-voltage engine with a power from a few watts to 1000 watts at a supply voltage of not more than 20 V. The sensor of the electronic ignition system of a VAZ car is used as a speed sensor. This sensor is made on the basis of a Hall sensor and is a round magnetic screen fixed on an axis with slots that, during rotation, pass into the slots of the Hall sensor. As a result, pulses are generated at the output of the sensor, the frequency of which is directly proportional to the rotational speed of the shaft on which the magnetic screen is fixed. ... >>

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Articles on filters and matching devices

Articles on filters and matching devices; schemes of filters and matching devices; descriptions of filters and matching devices: 49 articles



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Latest news of science and technology, new electronics:

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 ... >>

Electron spin for quantum information transfer 18.05.2024

The transfer of quantum information remains one of the key tasks of modern science. Recent advances in the use of electron spin to expand the capabilities of information transfer in quantum systems have become very important. Researchers at Lawrence Berkeley National Laboratory are pushing the frontiers of quantum information science by experimenting with the possibilities of electron spin. Electron spin, a natural quantum bit, is a potentially powerful means for storing and transmitting information in quantum systems. Magnon wave packets, collective excitations of electron spin, have revealed their potential to transmit quantum information over significant distances. The work of Berkeley Lab researchers has revolutionized the way such excitations propagate in antiferromagnets, opening up new prospects for quantum technologies. Using pairs of laser pulses, scientists disrupted antiferromagnetic order in one place and simultaneously studied it in another, creating ... >>

Sound-absorbing silk 17.05.2024

In a world where noise is becoming increasingly intrusive, the emergence of innovative materials that can reduce its impact is of great interest. MIT researchers have unveiled a new sound-absorbing silk fabric that promises to revolutionize quiet spaces. The Massachusetts Institute of Technology (MIT) has made significant breakthroughs in the field of sound absorption. Researchers have developed a special silk fabric that can effectively absorb sound and create cozy, quiet environments. The fabric, thinner than a human hair, contains a unique vibrating fiber that is activated when voltage is applied to it. This feature allows the fabric to be used to suppress sound waves in two different ways. The first method uses fabric vibrations to generate sound waves that cover and cancel out unwanted noise, similar to noise-canceling headphones. This p ... >>

Random news from the Archive

Oxygen from moon dust 01.05.2023

A team of researchers was able to extract oxygen from a model of lunar dust. In the future, they hope, this will help the colonizers of the moon.

The experiment was conducted at the Johnson Space Center in Houston.

Scientists knew that the soil on the moon contained compounds that could be used to produce oxygen through solar radiation. To test this, they created a model of fine-grained soil that mimics the material that covers the Moon's surface.

Using a powerful lens-like laser, the team melted down a simulated lunar soil. Carbon monoxide and oxygen were found in the resulting sample.

Aaron Paz, NASA senior engineer and project leader, said: "This technology can produce huge amounts of oxygen on the surface of the moon, which will provide a sustainable human presence and a monthly economy."

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