Pirate phone blocker. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Telephony
Comments on the article
The described device protects the subscriber's telephone line from unauthorized connection of a "pirated" device.
The proposed blocker uses some of the circuit solutions described in the materials published in the "Radio" earlier [1, 2].
The blocker is easy to manufacture, does not require additional power. It is carried out from the telephone network. Consumed current - no more than 160 μA. The device is assembled on publicly available elements, does not need to be configured.
Connect the blocker to the break in the telephone line at the entrance to the apartment, observing the polarity. When the tube lies on the device, the voltage in the line is 60 V, while current flows through the zener diode VD4 into the base of the transistor VT2. Transistor VT2 is open. When the tube is removed, the voltage in the line drops to 5 ... 15 V, the zener diode VD4 closes. If the handset was removed by the owner from the device connected after the blocker, the transistor VT1 opens, the collector current of which maintains the transistor VT2 in the open state. There is a low level on its collector and on the control input of the K1 key. The key is closed and the telephone line is not shunted.
If a "pirate" phone is connected (before the blocker), the voltage in the line drops, the transistor VT2 closes, since the transistor VT1 and the zener diode VD4 are closed. Capacitor C3 is charged through the circuit VD1, DA1, VD3, R3, R5, key K1 opens and resistor R2 shunts the pin. Dialing by a "pirated" phone becomes impossible.
Current stabilizer DA1, zener diode VD2 and capacitor C1 provide power (3 V) to transistor VT2 and circuit R5C3. At the moments of closing the contacts of the dialer of the "pirate" phone, capacitor C2 feeds capacitor C3, and diode VD3 prevents the discharge of capacitor C2 through zener diode VD2.
The device uses capacitors: C1 and C2 - K50-16, C3 - KM-6. The VD4 zener diode can be replaced with 2S220Zh, KS222Zh, 2S222Zh.
The device is assembled by surface mounting on a board with dimensions of 21x41 mm.
The described device is not certified, so it can only be used as part of PBXs and on lines that do not have access to the public telephone network. To increase the reliability of the device, we recommend shunting the emitter-base junction of the transistor VT2 with a 1 MΩ resistor.
Literature
- Ganzhenko G., Korshun I. Against telephone pirates. - Radio. 1996. No. 10, p. 45.
- Movsun-zade K. "Watchman" of your phone. - Radio. 1997. No. 11. p. 53
Author: V.Davidenko, St. Petersburg
See other articles Section Telephony.
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 Nanopurification of water and soil
08.08.2015
Chemical pollutants often turn out to be elusive and difficult to destroy - the molecules of many pesticides and, for example, bisphenol A, used in the production of plastics, are very resistant to decomposition under normal conditions, so that cleaning water and soil from such substances becomes a very expensive and time-consuming matter: after all, here it is necessary to somehow catch pollutants from the environment in order to destroy them later by special methods.
Researchers at the Massachusetts Institute of Technology have created special nanoparticles that could greatly simplify the fight against such pollutants. Ferdinand Brandl (Ferdinand Brandl), Nicolas Bertrand (Nicolas Bertrand) and their colleagues synthesized a polymer substance from polyethylene glycol and polyactic acid - the first is part of eye drops, toothpastes, laxatives, etc., and, therefore, is harmless, and the second serves as one of the main components of biodegradable plastic. Nanoparticles made of such a polymer consist of a hydrophobic core and a hydrophilic shell; due to molecular forces, hydrophobic contaminants, trying to get to the inner layer of the nanoparticle, will stick to its surface.
But in this form, the pollutant will remain in solution, even if it sticks to the nanoparticles. The trick is that the polymer from which the particles are made is destroyed under the action of ultraviolet radiation so that the hydrophilic shell disappears, and the hydrophobic core unfolds, "explodes" - it is no longer stabilized by the hydrophilic shell, which, due to interaction with water, kept the interior of the particle in a compact condition. Expanded particles with adhering pollutant molecules stick together, and as a result, a rather large supramolecular aggregate is obtained. Only, unlike individual harmful molecules and individual particles, such aggregates are easy to collect: they can be precipitated by centrifugation or, for example, simply filtered.
Using these nanoparticles, scientists have been able to purify solutions containing phthalates and bisphenol A, which interfere with hormonal signaling pathways; the particles also proved to be effective in cleaning the soil from aromatic polycyclic hydrocarbons, which are formed during the incomplete combustion of various types of fuel and which, as is known, can be strong carcinogens. The unfolded polymer cannot fold back into a nanoparticle, and if for some reason the polymer microlump does not settle and filter out, then, made of biodegradable material, it will collapse itself over time, that is, there will be no additional pollution.
A huge plus of the method is its simplicity: the substance of nanoparticles is synthesized at room temperature, there is no need to modify them (they snatch substances from the solution non-specifically and are suitable for any hydrophobic chemicals), purification occurs without complex multi-stage procedures.
In addition, a sufficiently large ratio of surface area to volume allows a small number of nanoparticles to capture many harmful molecules. According to the initial thought of the authors of the work, such particles were supposed to deliver the drug to cancer cells, but the stumbling block was the need for ultraviolet light, which, firstly, does not pass well through the skin, and secondly, damages DNA in those cells, including healthy ones. which he did get to.
And yet, the method can find application not only in cleaning the environment from pollutants, but also in medicine, pharmacology, analytical chemistry, and even in the food industry: for example, using unfolding and sticking nanoparticles, it is possible to remove caffeine when preparing decaffeinated coffee.
|
Other interesting news:
▪ Life could have originated on Titan
▪ inflatable tablets
▪ Coyotes will be fed chocolate
▪ Breathing gets harder
▪ Newsweek magazine stops publishing in print
News feed of science and technology, new electronics
Interesting materials of the Free Technical Library:
▪ section of the site Tips for radio amateurs. Selection of articles
▪ article Your mournful work will not be wasted. Popular expression
▪ article From whom did the Russian princes (and tsars) Rurikovich lead their genealogy? Detailed answer
▪ article Snowcards for sports and recreation. Personal transport
▪ article Low harmonic signal generator. Encyclopedia of radio electronics and electrical engineering
▪ article Udmurt proverbs and sayings. Large selection
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