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Fluorescent lamps

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Antenna amplifier MV

Section Antenna amplifiers. The figure shows a diagram of an antenna amplifier designed to amplify the signals of all 12 MB channels. Its gain is 25 dB at a supply voltage of 12 V. Current consumption is 18 mA. Back-to-back diodes connected at the input protect the amplifier transistors from damage by lightning discharges. Both cascades are assembled according to a common emitter circuit. Capacitor C6 provides frequency correction of the amplifier characteristics in the high frequency region. To stabilize the transistor mode, the amplifier is covered by negative feedback from the emitter of the second transistor to the base of the first. To avoid self-excitation of the amplifier due to parasitic feedback between stages through the power supply, decoupling filter R4 C1 is used. The amplifier is installed in close proximity to the antenna and power is supplied to it through a cable isolation ... >>

Propagation of radio waves

Section Beginner radio amateur. In conclusion, it must be said that radio waves of different ranges have unequal properties that affect the range of their propagation. Waves of one length travel long distances, waves of another length are lost beyond the horizon. It happens that the radio signal is perfectly audible somewhere on the other side of the Earth or in Space, but it cannot be detected a few tens of kilometers from the radio station. If we tuned the receivers to nearby radio stations operating in the ranges of ultrashort, short, medium and long waves, then, moving away from the stations, we could observe the following phenomenon: already a few tens of kilometers away, the reception of ultrashortwave and shortwave stations would stop, after 800- 1000 km would stop hearing the transmissions of the medium-wave station, and after 1500-2000 km - and the transmissions of the long-wave station ... >>

Stable local oscillator VHF converter

Section Nodes of amateur radio equipment. Generators, heterodynes. As non-tunable local oscillators for converters in the 144-146 MHz range, tube or transistor self-oscillators are usually used, stabilized by quartz, generating in the range of 10-50 MHz (the quartz resonator is excited at the third - fifth mechanical harmonic), and two - three frequency multiplication stages. At the same time, single-stage transistor local oscillators stabilized by quartz at the highest (up to the eleventh) mechanical harmonics have a number of advantages: the absence of low-frequency harmonics with sufficiently large amplitudes in the signal spectrum, small dimensions, which allow completely shielding and thermostating the local oscillator block with fairly simple means, low temperature instability of the output signal amplitude (due to the presence of a minimum number of narrow-band circuits), greater reliability (due to a smaller number of elements) ... >>

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Articles on fluorescent lamps; descriptions of fluorescent lamps: 50 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

Elevator across the highway 24.02.2003

In Germany, on the federal highway ?132, there is an elevator across the street.

It consists of two towers and a bridge between them, along which a passenger cabin runs, accommodating up to 8 people. The trajectory of the movement of the elevator car consists of two vertical and one horizontal sections. As in a conventional elevator, when moving vertically, the cabin is balanced by counterweights.

Moving at a speed of 1 m/s vertically and 1,5 m/s horizontally, the elevator overcomes a four-lane road in about 30 s. In the event of a power outage, the elevator automatically switches to battery power.

The indisputable advantage of the new way for pedestrians to overcome highways and other similar obstacles (railways, canals, etc.) is its increased safety, however, achieved at the cost of additional investments. Therefore, the mass introduction of new items is expected, mainly in countries where human life is considered the highest value, and in the near future we are most likely not threatened.

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