Lamp spy transmitters. Transmitters - "Spies". Download free Book: "Spy Passion. Electronic devices of double use"

VHF microswitch for a telephone

If you need a wireless remote listening of telephone conversations on your (someone else's) telephone, then you will be useful for a miniature transmitter diagram with frequency modulation, designed to work in the VHF range at frequencies of 63 ... 80 MHz together with any everyday radio.

The circuit is powered by the telephone line only during the conversation when the handset is raised.

The conversation of the radio in the range of the range, where there are no broadcasting stations. Radius of the transmitter without the use of WA1 antenna to 50 m, and to increase the range, except for the use of antenna, it is necessary to use a high sensitivity receiver. Thus, an increase in the sensitivity of the receiver 2 times the same increases the range of reception. When connecting the device to the telephone line, the polarity specified in the diagram must be observed. The setup of the scheme is to restructure the generator core of the coil L1 to the desired frequency of the range of the range, and then the transmitter must be adjusted by the transmitter by controlling the reception in the quality of the transfer by hearing. Frequency modulation in the transmitter is obtained due to the change in the inner capacity of the transistor when the voltage fluctuations of the circuit is oscillate due to the current flow in the Ta line. Before setting the transmitter, it is necessary to connect it to the telephone line and when the tube is removed, the voltage on the R4 resistor is measured. It must be in the range from 2 to 3.5 V, and if the voltage is greater, then the resistance of this resistor should be reduced. The transmitter circuit is collected on a one-sided printed circuit board with a size of 20x40 mm, to which the elements are soldered to the contact sites. The size of the board allows you to place it in the chassis of the standard phone socket.

Condenser SZ Type CPCM, and the remaining used resistors and capacitors can be of any type, small. The L1 coil is wound on the frame with a diameter of 5 mm with a PEV wire of 0.23 mm and contains 5 + 5 turns. The KT315 transistor can be replaced by KT3102A, and other transistors are not recommended, since the level of harmonics, which can create interference in other bands increase. At the details indicated on the scheme, the level of the second harmonic of the transmitter is less than 40 ... 45 dB relative to the main frequency. As an antenna, you can apply a segment of any stranded wire with a length of 30 ... 40 cm. Setting to the desired frequency, if there is no high-frequency ferrite core, you can select the circuit of the circuit shown in the dotted line diagram. Condensors C1 and C2 may have a rating of 0.022 ... 0.068 μF. Connecting data schemes does not affect the quality of the phone.

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"Spy passions. Electronic devices of dual use"

Posted schemes, descriptions, features of the design and operation of small-sized dual-use transceivers are used both for communication purposes and unauthorized access to confidential information - electronic spying. More than 200 devices and nodes schemes are presented, whose joint use allows you to create more than thousand electronic structures. On the example of the simplest experiments are described possible methods Interception of information but some channels of its formation, processing and transmission (sound, radio, telephone, computer). Are given simple recommendations But the protection of information. The book is designed for a wide range of readers, constructing means of communication, as well as those who are worn out of electronics capabilities and is concerned about the protection of their own and other secrets.
Development and use of achievements of modern electronics | Filled to the emergence of new radio elements and devices based on them with new (often unique) wonderful parameters and consumer properties. The wide implementation of these elements and devices, especially in 5th, led to a fundamental conversion of living conditions.

Highly sensitive high-quality small-sized radio receivers, televisions, tape recorders appeared. The possibilities of modern personnel computers are affected by imagination. Audio and video, laser dis- \\ and, multimedia, virtual reality - New concepts, new possibilities, a new level that improves the quality of life. Means of communication launched the moss world. This is accompanied by a significant expansion of communication services. Through the computer, you can watch TV shows, listen to the radio, making purchases without leaving the house, almost instantly contact through the Internet or similar systems with any point in the world. The ether is closely: DV-, "B-, C-, VHF devices - television channels there is not enough space. Satellite and cable systems, radio and fiber-optic communication lines become familiar. And the cellular radiotelephone does not seem like something Outstanding. All this admires.

However, the wonders of electronics can cause not only delight.

The radio transmitter as a means of communication expands the capabilities not only our, our friends, colleagues and partners. A number of users of modern microelectronics products and methods for their achievement of them are not only honest and noble. And they do not always look only in the firing of a TV and a computer, or in the pylon pipe on the stars and the beauty of Phyodia, but, to deep regret, and in the lock wells. And they are listening not only to their phone, but also someone else's - and not from idle curiosity caused by a lack of tact and culture. And the damage from all this may be not only moral, but also economic.

Information acquires value and becomes a commodity. And how the goods are produced, stored, sell. And how the goods are kidnapped, they copy and resell without permission of the legal owner, violating his rights and apply economic damage to it.
And it is called all this - industrial, more accurately economic, espionage, implemented, as a rule, using all the achievements of modern microelectronics: amplifiers, receivers, transmitters, repeaters, tape recorders, televisions. Listing, spy, intercept messages. All used information transmission channels can be monitored: sound, telephone, radio, etc.

Currently, many special electronic meansintended for unauthorized access to someone else's information - for electronic spying. Such devices are different technical parameters, consumer properties, price. In most cases, in the design of these funds, as a rule, sufficiently simple principles and circuitry solutions are sufficient.

Some schemes of such radio-electronic devices or their individual fragments will be given and are described below, recommendations on design and configuration will be given. However, the goal is not to stimulate "enthusiasts" of industrial electronic espionage (or intelligence - who like more). The goal is the illustration of the possibilities of modern microelectronics, which can be achieved for different purposes.

Using high-quality elements and modern circuitry solutions, you can create highly efficient and compact communication tools. However, on the basis of the same elements and the same schemes, in a matter of minutes (or hours) in secondary qualifications, "on the knees", create a radio electronic devices espionage.

For those who are concerned about the protection of secrets - their or other, small or large, personal or production - and is intended this material. It is also designed for those who do not violate legal and moral laws, would like to get acquainted with some schematic solutions and using them to repeat some of the devices given or create their own radio constructions, of course, for the purpose of communication.

Basic elements of transceivers

Antenna amplifiers (Radio and TV), Antennas

Briefly about antennas

Antennas for transmitters

Using meter indicators

Antennas for receivers

AM- and CM-Radio Converters

VKHM- and AM-radio

FM and AM radio transmitters

Woki-Toki (Transceivers)

Alternative means of communication

Telephone repeaters

General issues

Unconventional use of radio resources

Power supply of stationary and autonomous devices

Protection of information

Professional information protection tools

Main stationary information security tools

Searching equipment

Likbez\u003e how to find a spy

S. Chertoprud.

Lovers of short-wave radio programs are often stuck to mysterious stations that transmit infinite sequences of numbers. The incomprehensible code is monotonously read in different languages \u200b\u200bfor men, female, and sometimes children's voices. Strange programs first appeared on the ether about forty years ago; The signal from such stations is very strong, but they never report any place of their location, or about the audience for which the broadcast is intended. Usually, the listeners, stumbled upon such a transmission, for some time they still try to disassemble the endless "three-five or two-nine ...", and then, confused, turn the knob to the settings on.

Extremely rare such radio stations transmit separate phrases or texts. For example, a few days before the dissolution of the Eastern Hermann External Intelligence "Staja" Nesterior Choir male voices Constantly performed a song about a little duckling. It was broadcast at the same frequencies as the usual instructions of the "Fighters of the Invisible Front".

The vocal abilities of officers of one of the most effective explorations of the Cold War period were able to appreciate only numerous "illegal" and agents from the GDR worldwide: for them the transfer meant the end of the career. Meanwhile, the song was heard not only scouts and counterpeople, but also numerous radio amateurs, who, in all likelihood, did not understand the meaning hidden in it, but the time of each session and the frequency of "spy stations" was fixed.

Singles against spies
From about the mid-1970s, with the advent of new receivers with digital devices for tracking transmitters, shortwave-enthusiasts took up "numeric stations" seriously. By that time it was already clear that mysterious radio cells belong to spyware and transmit encrypted messages for their agents in Other countries. Radio amateurs amounted to not only extensive lists of such stations with an exact schedule of their work, but also engaged in radio benefits to install their basing places.

As you know, radio communication in the short waves range provides messages to the maximum distant distances, communicating with each other even diametrically opposite points of the globe. Accordingly, the KV-radio transmits are an ideal tool for anonymous one-sided communication. An intelligence agent at any point of the planet can receive messages from the manual using a small, publicly available and not a modified radio receiver.

From numerous documentaries and memoirs of retired intelligence officers, it has long been known that so-called disposable notebooks are used to encrypt such messages - the cryptosystem is absolutely not opened when proper use. True, stories are known and cases of fatal errors, when the "disposable" cipher was used repeatedly, which led to its autopsy, reading the secret correspondence and the arrest of agents.

The most famous history of this kind is the American "Project of Wenon" (http://www.nsa.gov/docs/venona), which led to the exposure extensive network Soviet intelligence in the 1940-50s. Cryptoanalitics of the NSA (National Security Agency, NationalSecurityageency, the American Analogue of the Russian FAPSI) managed to decipher a part of the messages that the Soviet legal residency exchanged.

For those who want to surpass the NSB, there is an original Project Conet website on the Internet. The initiator of it was the small British company Irdial-Discs, which in 1997 released a set of four CDs with recording of spy "numeric stations" over the past thirty years. Now, by inspiring the series of well-known RSA Challenges competitions (Competitions for the opening of secret cryptotes Popular cipher algorithms conducted by RSA), Project Conet (http://www.ibmpcug.co.uk/~irdial/conet.htm) urges everyone to engage in opening of encrypted transmissions. At the same time, stations broadcast elected as an object of study located in Britain, USA and Germany.

It is unlikely that the intelligence of these countries will carry any damage from the actions of the Internet "cryptoanalytics". Open the cryptosystem of this level is not an amateur for an amateur. Most likely, such a kind of promotion, the company is simply trying to revive interest in a few stale goods. The fact is that any radio amateur It can write fresh transfers of "numeric stations" or buy a CD-ROM with such a selection. Interestingly, however, that, declaring the competition, the organizers for some reason forgot to call the sum of the prize.

Communication Intelligence, Comint - the oldest type of radio-electronic intelligence. Its main content is the detection and interception of open, classified, coded transmissions of connected radio stations, the direction finding their signals, analysis and processing of the mined information in order to open its content and locate the location of radiation sources. Information of radio accessories about enemy stations, the systems of their construction and the content of the transmitted messages allow to identify plans and plans of the enemy, the composition and location of its groups, place the location of their headquarters and teams of management, databases and starting sites of missile weapons and so on.

Here are three typical examples of messages of radio engineering intelligence:

Russian military network number 1.

Traffic consists of control sessions of radio communication every two hours, although the encrypted message was accidentally transferred once.

Call signs: roller-17, rink-22, roller-25, rink-44, rink-46, rink-55, rink-74, rink-80, roller-86, rink-93, rink-94, rink-100, SMALL BIG.

Frequencies: 2650 kHz (night), 5855 kHz (day).

Russian military network number 2.

Traffic in this network consists of a format message "5 digits word 4 digits 4 digits." Perhaps this is a type of encrypted message.

For example: "54828 Swints 0064 0392" or "11233 Armor 2207 7720".

Call signs: Cossack-24, Virus-11, Vintage-24, Ether-12.

Frequencies: 4517 and 5794 kHz.

Russian military network number 3.

Traffic in this network consists of exchanging information between aircraft, ships and flight management clause (airflow).

Call signs: Treasure 86 (airflower), meteor-24 (aircraft), Nagan-58, Klen-38, Wind-41, leader-24, hypnosis-60, winter-158 (ship).

Frequencies: 5360 and 5888 kHz.

This data is taken from one of the radio amateurs sites - http://www.wunclub.com. These people are fanatically looking for any secret radio stations, starting with the armies of all countries of the world and ending with aerospace agencies. It is clear that there are also radio stations in the list of agents and illegal intelligence officers, whether it is Israeli, American or Russian. Many radio amateurs are engaged not only by listening and recording "numeric stations", but also by conventional radio visor. If in the first case the damage from their activities is minimal (technical units of counterintelligence are closely tracking all communication sessions), then in the second they sometimes turn out to be more effective in the second. Indeed Lovers perform the same tasks that solves radio prospecting, but at the same time they have a unique opportunity to compare data that are obtained from operators not dependent on each other, which they cannot afford the military.

A little about ghosts
The international club of radio amphibians "Spooks" ("Ghosts") prefers not to advertise himself. According to mine technical capabilities And the effectiveness of the work of "ghosts" can boldly compete with the radio prospects of the world's leading powers. The club's activities began in the 1980s, when many radio amateur worldwide began to actively communicate with each other. In the mid-1990s, part of them were fascinated by radio visiting. "Ghosts" Interested not only location and parameters (schedule of gears, call sign, frequency) of individual radio stations, primarily military purposes, but also the content of the messages.

Unlike the USSR and subsequently, Russia, in the United States there are no prohibited for listening to frequencies (moreover, there are even issued reference books with the frequencies of terrestrial airport services, police, army). As a result, over the long years of the monitoring of the air, the members of the club accumulated information about how at what period did the detected transmitter worked. That is, in fact, everyone for himself was engaged in the fact that in the language of radio engineering intelligence, it is called "drawing up the schedule of activity." And this is a full part of the operation of intelligence, which allows you to analyze many data to predict events.

Here's what, for example, Viktor Suvorov wrote in the "Aquarium" about the possibilities of radio-electronic intelligence GRU: "On each radio station, the case is started at each radar: the type, purpose, where it is located, to whom it works, at what frequencies does it work ... I understand the messages to us or not, A schedule of activity is started to the station and each it is fixed to the air ... if each exit to the ether is fixed and analyzed, then it becomes possible to predict its behavior. As a result of many years of analysis, there is an opportunity to say: "If RB-7665-1 entered the air, it means that after four days there will be a massive takeoff in Ramstein." This is an indispensable law. And if it suddenly earned the station that we call C-1000, here And it is clear to the child that the combat readiness of the American troops in Europe will be raised ... ".

Who enjoys information extracted by "ghosts"? In addition to numerous websites of radio amateurs, which are now more than thirty, these are journalists, analysts and everything, who needs reliable information about the situation in a particular region. Although the analytical capabilities of "ghosts" are far from professional professionals But something they can and they are. As an example, the history of the identification of a group of Russian agents in the United States, former citizens of Cuba.

Phantoms against Cuban
On September 28, 1998, a message appeared on the electronic board of the club "Spooks" on the electronic board: "Two weeks ago, the Miami Herald newspaper reported that a group of Cuban spies in Miami was detained in Miami, 12 people who tried to penetrate the American military base in South Florida." The task was delivered to the radio amateurs - to establish how the arrest of Cuban spies on the activity of radio transmitters working from the territory of Cuba (it was the tasks of this kind in such situations that control the services of counterintelligence)

A week after the arrest of Cuban spies, Andy Andy Bell said that the station, which fans gave the number S7 Russian Man, suddenly moved to the daily operation. As mentioned by ghosts, before the arrest of spies, the transmitter went on ether only twice a week. Based on this, the hunters suggested that the duplication of messages may mean that the recipient does not respond to the signal. Since the S7 Russian Man's transmitter was previously held as the FAPSI (under this designation, in addition to transmitters of the FAPSI actually, the radio stations of other Russian intelligence services - CVR and GRU), was concluded that the Cuban group could have worked for Russians. Next (specifically for those interested) was made public technical informationNamely the frequencies on which the transmitter S7 Russian Man: 5937 kHz, 7737 kHz and 9337 kHz worked. According to some experts, the majority of programs for Russian intelligence agents were conducted from Cuba, where until recently there was a Lourdes Radio Hat Center. Choosing a place is not accident: small distance The United States has made it possible to use low-power compact radio stations for receiving and transmitting messages.

Radioles of all countries
"Ghosts" is not the only organization of this kind. In January 1995, the WORLDWIDEUTENEWS club began to operate, about which we have already written above. The "UTE" lettering means that club members are interested in radio stations operating in the frequency range up to 30 MHz. WUN headquarters make up 11 people from the USA, Europe, Japan, New Zealand, and simple participants have a lot more than a hundred. To date, there are almost no places on the planet who would not get into their field of view.

Such organizations are the structure that can only dream of any counterintelligence or radio repaid. First, they are elusive: only use only emailThey usually work under a pseudonym, never themselves broadcast, applying only equipment for radio monitoring, the benefit in many countries does not require registration. In cases where registration is officially needed, as in Russia, necessary equipment You can always purchase on the "black market."

Secondly, "ghosts" and their likes work against other countries and thereby do not conflict with local law enforcement agencies. For example, Americans prefer to listen to the transmitters who are in Cuba, China's citizens choose US radio stations, and Russians are Chinese. This is connected Not only with a sense of patriotism or instinct of self-preservation, but also with the technical characteristics of the organization of a secret radio.

Thirdly, for "ghosts" is characteristic high level efficiency and reliability. Thanks world Wide Web"Any fresh information is almost instantly becoming known to all club members. Fourthly, radio amateurs are extremely professional and carefully study all available information on the organization of radio visor and radio-electronic combat (RES).

The acoustic generator is designed to guide interference in the places of confidential negotiations. It forms "white" noise in the entire range sound Frequency. Transmission of acoustic oscillations occurs through piezoelectric vibrators and acoustic speakers

This transmitter is designed to transfer information. telephone conversation At the VHF receiver in the range of 68-108 MHz. The range of the repeater is 50-100 m

The scheme's detailed scheme is very easy to repeat by any novice radio amateur and is able to register the fluctuations of the walls with a thickness of up to 0.5 m or a whole rising of heating batteries.

Typically, radio fairs are operating at one frequency in the range of 30 ... 500 MHz with a low radiation power not more than 5 MW. More advanced radio layers can work in waiting mode and begin to radio transmission in the presence of a threshold noise level, which reduces their probability of detection. Many radio bugs love to "dwell" in telephone or outlets 220 in as they do not require their own power source

A selection of uncomplicated homemade structures of radio bugs with powered from one 1.5 volt element, with a very low current consumption. Such a radio layout can work offline for a very long time with the transmission of radio signal to a distance of 30-60 meters.

This method of protection against laser devices is that with the help of special devices to make the glasses vibration amplitude much more than caused by the voice of a person. At the same time, difficulties in detecting a speech signal arise on the receiving side

Excellent selection of good circuitry solutions of television video studies for wireless transmission Video signal from video cameras, satellite receivers, game consoles and many other devices. Video transmitters circuits operate in the standard frequency range of 470-580 MHz and can be taken from 21-34 channels with almost any TV. The video signal is capable of transmitted to a distance of 50-100 meters using a short antenna from a conventional piece of copper wire.

The presence of a camcorder in modern realities is not particularly surprised. It can be used to reflect the important points of our life, the life of our relatives or relatives, as well as our competitors in our professional life. In this review article, consider the main schemes and methods of connections for different goals of their advantages and disadvantages.

In order to eliminate work mobile phone and mobile Internet In some places, for example in theaters or educational institutions, during exams, you can use homemade GSM signal silencers for cell phones.

This bug is recommended for repetition of novice radio amateurs and young spies. Firstly, it is not difficult, consists only of available radio components and feeds from the 9 volt battery. The radius of its action is up to 200 meters, in conditions of the city can be less, it all depends on the transistor bug used in the scheme. The scheme was borrowed in the English-speaking site, but it is fully operational, because tested in the assembly.

Transmitters - "Spies"

We bring to your attention a few designs of miniature transmitters.

Required devices and tools:

1. Amploltmeter (autometer) with a linear scale (shooter) with 30V measurements limits, 150V, 15V, current 15 mA, 150 mA.

2. Wrometer - the diagram is shown below:

The L1 coil contains 4.5 turns of the wire with a diameter of 1-1.5 mm, wound on the mandrel, with a diameter of 16 millimeters. The removal is made from 2 turns. A coaxial cable segment is used as an antenna. The fever and the inner custody solder together. Cut length - 100 millimeters. Micro ammeter - 50-100 microamper. Constructively, the wave is performed in a metal case.

The calbere graduation is better to produce with the help of a high-frequency generator, but you can use the auxiliary generator and a radio receiver for this purpose with a digital scale. The generator can be collected according to one of the schemes described below. First, on the scale of the receiver, we find the frequency of the auxiliary generator, then tighten the carrier on this - the same frequency and opposite the capacitor pointer of the carrier make a mark. So consistently produce all calibration on operating frequencies in the range of 88-108 megahertz.

3. Control transmitter.

The control transmitter scheme is shown below:

This transmitter is assembled by typical scheme and has the maximum repeatability.

About the details: Microphone - type MKE-332 ... 333a, transistor - CT3102A-B, you can apply CT315, but they have a large scatter of generation current. The coil has 6 turns, the wires of the PEV 0.45-0.7 on a blank of 6 millimeters (winding - closely), the removal - from 2 turns (counting from above according to the scheme). The frequency of the collected scheme 82 ... 90 megahertz. The frequency is changed by a variable capacitor. Antenna - a piece of a stranded wire, 200-260 mm long.

Setting: connect the power supply (9 volts!), Consistently with a source turn on a milliammeter. Current consumption must be within 8-10 milliam. Selection of consumption currents We produce with a resistor R2. Next, we connect the antenna and configure the transmitter to the desired frequency.

The control transmitter can also be used for pre-selection of transistors (with mass production). To do this, the transistor connects the panel to the location of the transistor and insert the test transistor into it (it is clear that before changing the transistor - you must definitely disable the power supply!).

Transistors are selected at the same consumption current. It is also useful at the R2 resistor to use several (for example, 43, 51 and 62 kiloma) resistors and a switch to the corresponding number of positions. In the future, with mass production, the nominal value corresponding to the optimal transistor for this resistor is falling into place. To manufacture the transmitter in one instance, the transistor preliminary check can be not done, but then you may have to select a resistor in the finished design - and this is not entirely convenient if you consider the miniature design ...

4. Installation tools (tweezers, nippers, soldering iron with accessories).

5. Materials: Fungalized fiberglass, winding wire, paraffin - to fix the coils of coils after tuning, zapon type lacquer.

A little about the antennas: The descriptions will meet the notation of the antenna A1 and A2. Antenna A1 is a segment of a wire, about 300 millimeters long, antenna A2 - a wire segment with a length of about 1 meter.

A typical transmitter diagram with an antenna A2 provides a range of communication in the city - up to 500 meters (manufacturer data). For the operation of the transmitter at a fixed frequency, the C6 condenser is replaced with a constant capacitance capacitance of the corresponding nominal.

The circuit of the transmitter with increased power is shown below:

The range of the transmitter with an antenna A2 - 1-1.2 kilometer at a voltage of the 9 volt power supply voltage. Current current - about 28 milliammeter.

This transmitter consists of a typical and supplemented with a power amplifier on the VT2 transistor. The scheme is characterized by increased frequency stability and less dependence on external factors. This allows you to wear a transmitter on the body ...

O details: L1 - 6 turns, wire 0.47, on the mandrel, with a diameter of 3.5 millimeters, L2 - 4 turns, on the mandrel of 2 millimeters, a wire with a diameter of 0.3 mm. L3 - On the mandrel of 2.7 mm - 7 turns, the diameter of the wire is 0.3 mm. When laying the transmitter, the coils L1 and L3 should be mutually perpendicular to! The L2 coil is placed inside the coil L1. The remaining parts are both in a typical transmitter.

Setting: First, we configure the specifying generator on the T1 transistor - a change in the value of the resistor R2 we achieve a current consumption current of 10 mA. Next, we collect the output cascade on the T2 transistor. When the antenna is connected by moving the L2 coil, we achieve consumption current of about 26-28 mA. Further - by the carrier we achieve the maximum output power (a selection of contour capacitors - roughly and swaying the coils - smoothly).

The transfer transmitter from the telephone line is below:

To work in telephone lines, the transmitter must have 10-12 mA consumption current in lines without a block and 16-18 mA in lines with a block. The transmitter is assembled according to a typical scheme. To obtain the desired consumption current, it is necessary to put transistors with a selected current consumption of 7-8.5 mA with a base resistor 2 times less than the one that was used when a selection of the transistor. The microphone in this scheme is not needed. Modulation is carried out by power during a conversation ... the adjustment of the transmitter is not different from the typical one. Capacity C2 capacitor is 0.022 microfrarad. Several words should be said about the design of the antenna. For the manufacture of antenna, a piece of an isolated single-core wire is used, a length of 210-240 mm. At one end, insulation is cleaned for soldering. A segment of the winding wire is soldered to the studded end, about 200 mm long and the main antenna wire is winding, approximately 20 millimeters width in several layers. The opposite end of the wire is soldered into the scheme. After making the winding should be fixed. It turns out an antenna with distributed inductance. This measure made it possible to significantly reduce the size of the antenna practically without reducing the radiated power (in this design, for an understandable reason, it was sought to get possible smaller sizes). The range of validity in the city (filed by the manufacturer) is 200-350 meters. The transmitter turns on when picked up the tube.

The transmitter L1 coil is winding on a 3 mm twist to the twist and contains 6 turns, a wire with a diameter of 0.3-0.4 mm. The setting is almost no different from the setting of the standard transmitter. Customize the frequency by the selection of the contour capacitor and spuning the coil's turns.

The transmitter diagram on the field of transistor is shown below:

The scheme is characterized by reduced power consumption. Selection of transistors is not needed. output power equal to the output power of the type transmitter when twice the current consumption. Frequency care When changing the supply voltage from 3 to 9 volts - no more than 0.2 megahertz (stated by the manufacturer). Coil parameters - as in the transmitter base diagram. Disposal for connecting an antenna is made from the second turn. The diagram can be used both an independent transmitter and as specifying in a more powerful (similar to the transmitter diagram with an increased output power).

All of the above transmitters operate in the frequency range 88-108 Meghertz (FM range). To restructure on the FM range (64-72 megahertz), it is necessary to increase the number of turns of contour coils by 1.4 times. The length of the antennas should also be increased 1.4 times. You can not increase the antenna length, but it will slightly reduce the range of transmitters.

Several words should be said about the installation. To give the design of sufficient rigidity and reliability, all transmitters should be made on printed circuit boards. When developing pCB It is necessary to strive to reduce all conductors to a minimum. The length of the findings of parts is reduced to the minimum possible. It is theoretically possible to make a transmitter according to a typical scheme on the board with an area of \u200b\u200bno more than 1 square centimeter. After setting, the transmitter should be coated 2-3 times by quick lacquer - to increase the stiffness of the structure. The coating is better to produce dipping (it is pre-soldered all external conductors). The length of the wires and the microphone must also be minimal. Useful after the assembly to place the transmitter into a sealed metal casing, which should be connected to the general ("minus") conductor of the board in one (!) Point. All these measures allow you to improve the reliability of the transmitter during operation.