Encyclopedia of radio electronics and electrical engineering / radio reception
Comments on the article
This receiver is also called regenerative. It is designed for listening through a microtelephone type TM-2, TM-4 of radio stations operating in the medium wave range. Its basis is a direct amplification circuit with a UHF regenerative stage. Due to the positive feedback (circuit R5, C3), the depth of which is regulated by the resistor R5, the sensitivity and selectivity of the receiver is increased. The amplified signal from the UHF is fed to the detector VD1, VD2, assembled according to the voltage doubling scheme, and after detection, the ULF is amplified on transistors VT2, VT3.
A ferrite rod 50...90 mm long and 8 mm in diameter is used in the input circuit of the receiver. Coils L1 (75 turns of wire brand LESHO 30x0,05) and L2 (8 turns of wire brand PEV-1 with a diameter of 0,3 mm) are fixed on it.
The receiver is adjusted by setting the operating mode of the transistors to direct current. The resistor R3 sets the collector current of the transistor VT1 within 0,7 ... 1 mA, and by selecting the resistances of the resistors R7 and R9 - the collector currents of the transistors VT2 and VT3 (respectively 0,2 ... 0,3 mA and 0,4 .. .0,5 mA).
The receiver is quite economical (current consumption 1,5 ... 2 mA). Therefore, two series-connected disk batteries of the D-0,06 or D-0,1 type can be used to power it.
The receiver is tuned to the radio station using a variable capacitor C2, and its sensitivity is adjusted by resistors R5 and, if necessary, R3.
Author: B. Evgeniev
See other articles Section radio reception.
Read and write useful comments on this article.
<< Back
<< Back
Latest news of science and technology, new electronics:
Artificial leather for touch emulation
15.04.2024
In a modern technology world where distance is becoming increasingly commonplace, maintaining connection and a sense of closeness is important. Recent developments in artificial skin by German scientists from Saarland University represent a new era in virtual interactions. German researchers from Saarland University have developed ultra-thin films that can transmit the sensation of touch over a distance. This cutting-edge technology provides new opportunities for virtual communication, especially for those who find themselves far from their loved ones. The ultra-thin films developed by the researchers, just 50 micrometers thick, can be integrated into textiles and worn like a second skin. These films act as sensors that recognize tactile signals from mom or dad, and as actuators that transmit these movements to the baby. Parents' touch to the fabric activates sensors that react to pressure and deform the ultra-thin film. This ... >>
Petgugu Global cat litter
15.04.2024
Taking care of pets can often be a challenge, especially when it comes to keeping your home clean. A new interesting solution from the Petgugu Global startup has been presented, which will make life easier for cat owners and help them keep their home perfectly clean and tidy. Startup Petgugu Global has unveiled a unique cat toilet that can automatically flush feces, keeping your home clean and fresh. This innovative device is equipped with various smart sensors that monitor your pet's toilet activity and activate to automatically clean after use. The device connects to the sewer system and ensures efficient waste removal without the need for intervention from the owner. Additionally, the toilet has a large flushable storage capacity, making it ideal for multi-cat households. The Petgugu cat litter bowl is designed for use with water-soluble litters and offers a range of additional ... >>
The attractiveness of caring men
14.04.2024
The stereotype that women prefer "bad boys" has long been widespread. However, recent research conducted by British scientists from Monash University offers a new perspective on this issue. They looked at how women responded to men's emotional responsibility and willingness to help others. The study's findings could change our understanding of what makes men attractive to women. A study conducted by scientists from Monash University leads to new findings about men's attractiveness to women. In the experiment, women were shown photographs of men with brief stories about their behavior in various situations, including their reaction to an encounter with a homeless person. Some of the men ignored the homeless man, while others helped him, such as buying him food. A study found that men who showed empathy and kindness were more attractive to women compared to men who showed empathy and kindness. ... >>
| Random news from the Archive Nanoneedles will speed up the delivery of molecules to cells
06.11.2018
Nanostructures with tiny needle-like protrusions can make tiny holes in cell walls for convenient and fast delivery of "cargo" - molecules specially designed for gene editing, cancer treatment or monitoring the development of stem cells in the body.
The idea of transporting chemicals into a cell through its membrane is not new: there are several methods of delivery today, but they have their drawbacks. One method is electroporation. Its essence is that with the help of an electric current in the cell membrane, they create pores through which molecules - for example, DNA or protein - can penetrate, but this method is inaccurate and can kill many cells that the researchers "aimed at".
Another way is to deliver molecules to the cell wall with the help of viruses. This method also does not inspire full confidence - like the viruses themselves, carriers of diseases. In addition, these strategies are not suitable for working with immune cells.
The new method, developed by a team of scientists from Stanford University, uses, like the first, an electric current, but works with it much more delicately. When the current is turned on, nanostructures with thin "needles" leave tiny "holes" on cell membranes, through which a molecule can pass and which will not cause damage. At the same time, the current is concentrated in a specific place and, moreover, directs the molecule to the desired "input", which ensures the accuracy and speed of the process: delivery of the molecule to the cell takes only 20 seconds.
The method was tested on mouse brain cells and on three trips of human cells, with positive results in both cases. Now the authors of the development are planning to test their method on immune cells. If they succeed, it will take immunotherapy a few steps forward.
|
Other interesting news:
▪ Corsair Virtuoso RGB Wireless XT Headset
▪ LED turns vegetables into medicinal plants
▪ 176-layer 4D NAND Flash
▪ Electromagnetic generator operating without fuel
▪ The danger of extinction of insects
News feed of science and technology, new electronics
Interesting materials of the Free Technical Library:
▪ section of the site Mobile communications. Article selection
▪ article Types of means and methods of sending distress signals. Basics of safe life
▪ article Why did the Mason-Dixon line appear? Detailed answer
▪ article Toolmaker. Standard instruction on labor protection
▪ article Stepper motors. Encyclopedia of radio electronics and electrical engineering
▪ article Fluxes, pastes, inks, varnishes. Encyclopedia of radio electronics and electrical engineering
Leave your comment on this article:
All languages of this page
Home page | Library | Articles | Website map | Site Reviews
www.diagram.com.ua
2000-2024
Arabic
Bengali
Chinese
English
French
German
Hebrew
Hindi
Italian
Japanese
Korean
Malay
Polish
Portuguese
Spanish
Turkish
Ukrainian
Vietnamese