Radio stations, transceivers. Schemes, articles of the Free Technical Library

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Radio stations, transceivers. Schemes, articles, descriptions

Free library / Schemes of radio-electronic and electrical devices

Radio stations, transceivers

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Solar collectors. Drying

Section Alternative energy sources. A solar collector that heats the air can serve as a cheap source of heat for drying crops such as grains, fruits or vegetables. Since solar collectors with high efficiency heat the air temperature in the room by 5-10°C (and complex devices - even more), they can be used for air conditioning in warehouses. The use of simple and cheap solar collectors to heat the air while drying crops is promising in reducing the huge crop losses in developing countries. Lack of adequate storage conditions leads to significant food losses. Although it is impossible to accurately estimate the extent of crop losses in these countries, some sources estimate them at about 50-60% ... >>

Protection of equipment from increased mains voltage using an integral timer

Section Protection of equipment from emergency operation of the network, uninterruptible power supplies. Measuring and household appliances can be easily damaged by excessive increases or decreases in supply voltage. The voltage-sensing circuitry on the 555 integrated timer disconnects the equipment from the mains supply when the voltage is outside the specified limits. This circuit provides better device protection than a voltage regulator, which is effective at detecting and compensating for short-term voltage changes. As shown in the figure, the mains voltage is reduced to approximately 15 V using a step-down transformer, the transformation ratio of which depends on the voltage on the primary winding. The secondary voltage is rectified, filtered by a capacitor and fed to a 12V regulator, which biases the timer and the KT315 transistor used as the sensing element. ... >>

Fan switch with timer

Section Clocks, timers, relays, load switches. After 3 ... 5 minutes after turning on the fan, this device turns it off and turns off by itself, no longer consuming energy from the 220 V network. The device diagram is shown in fig. 1, and its appearance - in Fig. 2. When you press the SB1 button, the mains voltage is supplied to the winding of the transformer T1. The second group of contacts of the button closes the charging circuit of the capacitor C1 to the voltage at the output of the rectifier, consisting of a diode bridge and a smoothing capacitor C2. As a result, the transistor VT1 opens, the relays K1 and K2 are triggered ... >>

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Articles on radio stations, transceivers

Articles on radio stations, transceivers; schemes of radio stations, transceivers; descriptions of radio stations, transceivers: 197 articles

Articles on finalizing the RA3AO transceiver (V. Drozdov)

Articles on the RA3AO transceiver; RA3AO transceiver circuits; RA3AO transceiver descriptions: 22 articles

All articles on civil radio communication

Latest news of science and technology, new electronics:

Air trap for insects 01.05.2024

Agriculture is one of the key sectors of the economy, and pest control is an integral part of this process. A team of scientists from the Indian Council of Agricultural Research-Central Potato Research Institute (ICAR-CPRI), Shimla, has come up with an innovative solution to this problem - a wind-powered insect air trap. This device addresses the shortcomings of traditional pest control methods by providing real-time insect population data. The trap is powered entirely by wind energy, making it an environmentally friendly solution that requires no power. Its unique design allows monitoring of both harmful and beneficial insects, providing a complete overview of the population in any agricultural area. “By assessing target pests at the right time, we can take necessary measures to control both pests and diseases,” says Kapil ... >>

The threat of space debris to the Earth's magnetic field 01.05.2024

More and more often we hear about an increase in the amount of space debris surrounding our planet. However, it is not only active satellites and spacecraft that contribute to this problem, but also debris from old missions. The growing number of satellites launched by companies like SpaceX creates not only opportunities for the development of the Internet, but also serious threats to space security. Experts are now turning their attention to the potential implications for the Earth's magnetic field. Dr. Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics emphasizes that companies are rapidly deploying satellite constellations, and the number of satellites could grow to 100 in the next decade. The rapid development of these cosmic armadas of satellites can lead to contamination of the Earth's plasma environment with dangerous debris and a threat to the stability of the magnetosphere. Metal debris from used rockets can disrupt the ionosphere and magnetosphere. Both of these systems play a key role in protecting the atmosphere and maintaining ... >>

Solidification of bulk substances 30.04.2024

There are quite a few mysteries in the world of science, and one of them is the strange behavior of bulk materials. They may behave like a solid but suddenly turn into a flowing liquid. This phenomenon has attracted the attention of many researchers, and we may finally be getting closer to solving this mystery. Imagine sand in an hourglass. It usually flows freely, but in some cases its particles begin to get stuck, turning from a liquid to a solid. This transition has important implications for many areas, from drug production to construction. Researchers from the USA have attempted to describe this phenomenon and come closer to understanding it. In the study, the scientists conducted simulations in the laboratory using data from bags of polystyrene beads. They found that the vibrations within these sets had specific frequencies, meaning that only certain types of vibrations could travel through the material. Received ... >>

Random news from the Archive

Radio bug in a cigarette 17.03.2000

The need to obtain important information forced Russian scientists from the foreign intelligence service to develop a unique listening device - a "bug", which cannot be detected even with the most modern search tools.

The "bug" does not have a battery, but instead uses a combustible thermocouple hidden in the tobacco of a cigarette. The "bug" microphone is mounted in the filter. After the Russian James Bond lights a cigarette, the thermocouple will generate current, the transmitter microphone will turn on and begin to broadcast all the words that sound within a radius of several meters.

The disadvantage of the "bug" is its fragility: the bug cigarette is suitable for single use. However, if you wish, you can save the cigarette butt and later install the "bug" in a new cigarette. The cost of "bug" on the black market is about $500.

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