Radio prefix to the autoguard. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Security devices and object signaling
Comments on the article
Most car alarms, when triggered, inform the owner of an attempt on his property by giving a sound signal. Some use a car horn as a sound emitter, others use block sirens. But they have one drawback in common - the notification range is limited not only by distance, but also by the soundproofing of the building in which the owner of the car is located. As a result, in winter, when all the windows and vents of the apartment are not only closed, but the gaps in them are filled with insulation, and a desiccant is filled between the frames, the volume of the car alarm becomes insufficient to be heard in the apartment.
In this sense, a radio autoguard is more attractive, but it is usually much more expensive than an acoustic signal, and a home-made version requires the construction of complex receiving and transmitting paths, an encoding and decoding device.
The use of such a complex device is justified when the signal transmission range should be about 1-2 kilometers, but if you need to transmit a signal, for example, from a parking lot in the yard to the 5th floor of a nearby house (100-150 meters in general), you can use a simple a low-power VHF FM transmitter of the broadcasting range, and receive a signal on a conventional VHF FM radio receiver with a BSHN system. Such a transmitter can be connected with two wires in parallel to the car horn, which is used for signaling. Lay the antenna, which is a piece of mounting wire, along the rear window or place it inside the plastic bumper. And put the receiver on the windowsill, on the side where the car is standing.
A schematic diagram of such a simple transmitter is shown in the figure in the text.
The transmitter consists of a high-frequency oscillator on a VT1 transistor and a frequency modulator on a D1 chip. The generation frequency depends on the parameters of the circuit L1 C6 C7 C5 VD1. Feedback is capacitive, its voltage is taken from the connection point of capacitors C6 and C7 and fed to the emitter of transistor VT1. The inductor in the emitter circuit of the transistor provides the necessary decoupling between RF voltage and DC. As a result, transistor VT1 can operate in a mode with a relatively high collector current and deliver maximum power in the circuit. The bias voltage at the base of the transistor is set by resistor R3, capacitor C4 shunts the RF component of the base voltage of the transistor.
Frequency modulation is performed using a VD1 varicap, the role of which can also be played by a zener diode, for a voltage exceeding the transmitter supply voltage. Low-frequency voltage pulses with a frequency of about 1000 Hz are fed to the varicap from a multivibrator on the D1 chip.
Inductor DL1 is wound on a constant resistor MLT-0,5 with a resistance of more than 30 kOhm, it contains 60 turns of PEV 0,12. Coils L1 and L2 are frameless, they are wound with PEV 0,31 wire on a mandrel with a diameter of 5 mm. And for the range 87-108 MHz contains 6-7 turns, and L2 - 2 turns. For the range of 64-75 MHz - L1 contains 12 turns, L2 - 4 turns. Radioconstructor 02-2001, 32.
Author: Begunkov S.P.; Publication: N. Bolshakov, rf.atnn.ru
See other articles Section Security devices and object signaling.
Read and write useful comments on this article.
<< 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 Nanomechanical microchip sensor with ceramic coating
07.12.2021
The world's most accurate nanomechanical microchip sensor, combining nanotechnology and machine learning, was developed by researchers from TU Delft in the Netherlands. It will help to study dark matter, develop the quantum Internet, navigation and sounding.
Vibrating objects of the smallest size act in sensors or quantum equipment. It is very difficult to prevent them from interacting with ambient thermal noise. Sensors exist in a state of delicate balance, and even small interferences greatly affect their operation.
So, for example, a quantum computer can only work at temperatures around absolute zero (-273,15 °C). The necessary refrigeration equipment that provides such a temperature costs about half a million euros per copy. It is, of course, expensive. This sensor will allow you not to use refrigeration equipment.
Scientists have come up with a web-shaped microchip sensor that resonates well in noise isolation and operates at room temperature. The developers took an example from the device of the web, by the fluctuations of which the spider learns that the victim has already been caught. It is very good that hunting is not affected by the surrounding wind or various fluctuations outside. The authors believe that this is an ideal design that does not respond to external influences and is capable of creating isolated vibration.
Based on this analogy, the inventors created a microchip sensor by coating it with an ultra-thin nanometer-thick film of ceramic material.
|
Other interesting news:
▪ Dual-Image TVs
▪ Ultrasound makes the band-aid more sticky
▪ Computer in the plug
▪ After a hard day at work, people speak faster and louder.
▪ low cadmium rice
News feed of science and technology, new electronics
Interesting materials of the Free Technical Library:
▪ site section Measuring equipment. Article selection
▪ article I did not know what I wanted: either a constitution, or stellate sturgeon with horseradish. Popular expression
▪ Why Did Director John Ford Lose His Weather Forecaster Service? Detailed answer
▪ article Auctioneer. Job description
▪ article Save energy. Encyclopedia of radio electronics and electrical engineering
▪ article High-frequency power supply for a fluorescent lamp. 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