We have talked many times about the various components that make up an analog video surveillance system, but have repeatedly overlooked the younger brother, without whose participation more than one such system would not have taken place. We will talk about BNC connectors, a special connector that allows you to combine coaxial cables with a video camera and a DVR.
Principle of operation
A BNC connector with a characteristic impedance of 75 ohm is actively used to transmit a video signal from a video camera via a coaxial cable to the BNC connector “Female or Mother” of the DVR.
BNC socket.
The outer part of the connector has small grooves, thanks to which the connector, passing through the small recesses of the BNC socket, is securely fastened, while the central rod enters the socket socket. The connector is secured in the socket by a slight clockwise turn.
Types and types of mounting BNC connectors.
According to the type of fastening of the coaxial cable, BNC connectors are:
- Under the screw
- With terminal block
- Crimped (compression)
- soldered
- winding
BNC screw connector
BNC screw connector - fixes the central core of the coaxial cable with a screw, and the braid is clamped in a special holder. Important: The braid and the central core must not touch.
On the video: Installing a BNC connector for a screw
BNC connector with terminal block
A connector with a terminal block is easy to use, it is extremely easy to mount such a connector, the braid is inserted into the minus, and the central core into the +. The only drawback of this connector is the lack of a spring-holder, which does not allow the cable to become loose. For this reason, it is reasonable to install such adapters on the side of the camcorder in the junction box. On the side of the DVR, such a connector will not last long, it has been tested for years.
The crimped connector is one of the most reliable methods of connecting with a coaxial cable, the central core of the cable is placed in a brass core, and a crimp cap is put on top of the cable, all this is combined with the connector body and crimped with a special tool.
On the video: How to crimp a compression connector
BNC solder
BNC soldered as compression connectors are extremely reliable. By design, they resemble screw connectors, but the central core is soldered to the core. The braid can simply be clamped or soldered, since the soldering iron is in the hands. One of the disadvantages of such connectors is the inconvenience of mounting at a height, if compression connectors can still be contrived to compress the cable, then this is unlikely to be possible with a soldering iron at a height.
Screw-on BNC connector.
Such a connector is applicable for the RG-6 television cable, since only its rigidity and the thickness of the central core allow the connector to be fixed. The connection is quite reliable, resistant to loosening.
Cable for BNC connector
Any RG-6 type coaxial cable is suitable for the BNC connector. For ease of installation over short distances, it is more rational to use combined KVK cables. Such a cable has not only a braided coaxial core, but also carries two power cores, which greatly simplifies the installation of the video camera, since the signal and power are transmitted over one cable.
KVK 2 x 0.5
Such a wire is the cheapest of the combined cables, it carries supply wires with a cross section of 0.5 mm, the central wire must have a thickness of RK-75, which is far from the case in practice. With kvk-2x0.5, in general, they often deceive, then the power cores are 0.3, then the central one is as thick as a hair. The disadvantage of the cable is its insufficient thickness, it is not clamped by a spring at all, as a result, such a cable runs freely inside a metal cap with a spring.
BNC connector allows coaxial RF connections between network communications and video or audio equipment. Due to the reliable connection and the unique plug design, the user can expect high speed signal transmission without any significant attenuation or loss of data throughput between devices and coaxial conductors. This type of connection socket has a large number of various modifications, so a person, resorting to one or another installation model, can solve a variety of technical problems.
The most common type BNC connector are plugs that are made of metal and in some modifications are supplemented with fluoroplastic or special technological plastic. With a standard plug structure, the user needs to run a coaxial cable core into it and crimp it along the upper insulation screen. This operation must be performed by a person with experience in such manipulations, since it is necessary to resort to the use of universal tools that allow crimping the parts inside which the cable is enclosed.
When carrying out a perfect crimping job, the user can be sure that the conductor connected to the plug will not pull out. The core of the plug, depending on the type of construction, is nickel-plated, silver-plated or gold-plated. This structure of the connections allows for an ideal connection of a coaxial cable with a resistance of 50, 70 ohms. The tip of the plug has a unique cutout, so once it is plugged into the connector and rotated around its axis by the user, a tight engagement occurs that cannot be disengaged without additional cable extraction.
The user also has access to models of installations that have a triangle or angular shape. A tee allows you to simultaneously connect three coaxial conductors to each other, which in some cases is a splitter that makes it possible to branch the signal into several directions of communication networks. An angled plug is used when connecting equipment in which the connector is in close proximity to a wall or some other surface.
As you know, coaxial conductors should not be bent, therefore, when solving a problem with the fastest possible change in the direction of the conductor, using an angled plug is the best solution. The use of BNC connectors and adapters allows the user to make reliable and long-term connections of coaxial cable to electronic modules.
BNC Connectors created in the early forties by Amfenol in collaboration with Bell Labs, the developers were Paull Neill and Carl Councilman, hence the name BNS-bayonet Neill-Conceiman and denotes this electrical connector with fixation.
bnc rg connector There are several types that differ mainly in the way the central core is fixed to the braid. There are soldering, wrapping, crimping parts. Subtypes can also be used: BNC-F with threaded fastening, BNC-T for connecting a network and computer network card, BNC-I for splicing pieces of coaxial cable.
Features of BNC Rexant connectors
The BNC connector is a coaxial line filled with a dielectric with a resistance of 50 to 75 ohms and is designed to connect a coaxial cable to an equipment connector. signal distortion, that is, measuring instruments.
There are a lot of producing companies, but when you go to stores to buy bnc connectors and ask about quality, they recommend BNC connectors Rexant. If you go to the website of the online store of this company, you can find any details of interest, there is a wide variety of connectors. It is more profitable to buy through the Internet, because the price is cheaper, and the delivery is fast. BNC Recant connectors are reliable, do not break for a long time, they are airtight and have a good connection.
What are they used for Rexant BNC connectors
BNC connectors exist for connecting a coaxial cable to various electronic devices via a bnc connector and can be compressor, crimp type, bnc under the screw:
1.BNC compressor type connector, which is used in radio communication. Here, the connection is made using a plastic sleeve, which is snapped between the metal part of the housing and the cable sheath, while achieving tightness of the parts and a reliable connection. A special crimping or trimming tool is used. This is the most reliable connection to date.
2. BNC connector with crimp connection. This connection is mainly used for BNC CCTV, connecting video cameras and similar equipment.
For this connection, it is necessary to accurately select the size of the crimping tool. Part of the cable is cleaned so that the bnc connector is crimped and the cable is connected tightly and efficiently, then the wire insulation is protected, the cable is laid under the spring-loaded part and the bnc connector is turned several times with the cable, the insulation is cut. Next, the contact is put on the central core, we install the steel tube on bnc cable connector and clamp.
3. Screw bnc connectors are designed to connect monitors, camcorders or DVRs with a 50-75 ohm cable and a diameter of 7mm.
The connection takes place in this way: the cable is clamped using a bnc screw connector, with a metal cap and a spring at the end, which provide a reliable connection and tightness, protect the cable from external damage and kinks The easiest option to use and is not inferior to others in reliability, for example bnc connectors for video surveillance.
Where are BNC Rexant connectors used?
BNC plug The connector is used in many industries, but mainly it is commercial and industrial equipment and the commercial sector. They are used to connect radio-electronic devices and create Internet networks such as 10 BASE 2. It is installed in various equipment:
1. Measuring instruments, such as an oscilloscope for measuring amplitude voltage fluctuations.
2. digital video equipment: recorders, household equipment, but bnc connector not applied everywhere.
3.antennas and radio transmitters.
4.aviation and testing equipment.
Recant BNC connectors are widely used and help people at home and at work to connect the right equipment.
The BNC coaxial RF connector got its name from the names of the creators, engineers Paul Neil and Carl Konselman. The full name is "Bayonet Nile - Konselman". The word bayonet is of French origin and means a bayonet. The connector is closed using a lock, which was on the bayonet guns.
The BNC connector allows it to be used in circuits with voltages up to 500 V and frequencies up to 3 GHz (wavelength 10 cm). In this case, two standardized wave impedances are used: 50 and 75 ohms. If the BNC connector is used with the corresponding cable, and they match, then the loss on this connection does not exceed 0.3 dB.
Usually, a socket (“mother”) is installed in the equipment, and a plug (“father”) is installed on the cable. By design, BNC connectors are straight and angled. The latter are used where the cable must make a sharp bend, which is highly undesirable for coaxial cables. Therefore, this task is assigned to the angular structure.
The idea of a bayonet lock turned out to be very successful. The threaded connection is inconvenient to use, since it is necessary to rotate the cable along the axis. The situation is not always facilitated even by the union nut. Threaded connections are prone to sticking, hard to turn and take too long to connect and disconnect the connector. A friction-based connection, as in household appliances, is unacceptable, since the connector is very easy to pull out of the socket.
The bayonet closes and opens very easily. It is enough to press on the connector and turn it along the axis. All this takes less than a second. At the same time, it will not be possible to pull out the connector.
Therefore, the BNC connector has replaced almost all connectors among laboratory instruments. It is also best suited for computer networks - because of the speed of working with it and the impossibility of accidental disconnection.
BNC marking includes the following options:
- BNC - soldering or crimping;
- BNC-T - tee (for Ethernet adapters);
- BNC-F - a variant of the connector with a threaded tightening;
- BNC-I - connection of two cables.
For measuring devices, only solder connectors should be used, and preferably with gold-plated contacts. This reduces possible errors. For other cases, crimp connectors are suitable, but they must be mounted only with a special crimp tool. The latter version of the connectors is much cheaper than the instrument ones, it is mounted faster, therefore it is more optimal than soldering.
Thus, if you want to mount a local network of "n" computers, then this will require a minimum of "2n" connections on cables, and sometimes more.
For connecting various electronic devices, as well as for connecting cables between themselves, small knots called a connector or connector are used. There is a large number connector designs, but in modern technology for working with high-frequency signals, coaxial connectors are used, designed to work with cables that have a central core and a shielding braid. BNC screw connector is one of the most common modifications high frequency connectors.
Types of BNC connectors
The abbreviation BNC includes the word bayonet, which means bayonet, and the first letters of the names of the inventors Neil and Konselman. Each connector of this type, regardless of design features, consists of two parts. This is a plug part and a female part, called "father" and "mother". The female part is usually hard-mounted on the panel of the electronic device, while the plug part is located at the end of the cable. In this way, remote devices are connected to each other. In cases where it is necessary to connect two cables, the plug and socket parts are fixed at the ends of the cable lines.
BNC connectors in one of the versions have a spring-loaded latch. The plug part, thanks to the spring, is inserted with force into the socket part and then rotated clockwise, while the protrusion on the socket enters the groove of the plug and, after turning, firmly fixes the connection. To break the connection, the male part of the connector must be turned in the opposite direction and then removed from the female part.
Such a connection is very reliable and is not afraid of strong vibrations.
Structurally, BNC connectors have several varieties:
- BNC connector with cable soldering
- Compression BNC connector
- screw connector
- BNC connector with socket
- connector splitter
The plug part of such a connector consists of a central pin, to which the cable core is connected and a signal is transmitted, and an external glass (sleeve). The glass is fixed on the shielding braid of the cable. The BNC solder connector provides the most reliable connection. The cable core is inserted into the hollow channel of the pin and soldered. Depending on the design of the connector, the shielding braid can be soldered to a special tab or crimped with a metal strip. When laying cable lines, when it is required to connect two cables, this type of cable cutting is used. When using the correct solder, oxidation and destruction of the soldering point does not occur under any operating conditions.
Separate modifications of the connectors have a central pin, to which the cable core is not soldered, but is clamped under the screw. Such connectors much easier to install, since a soldering iron is not required, and therefore a 220 V network. The stripped central core of the coaxial cable enters the pin channel and is tightened with a screw. A BNC screw connector is not considered a reliable connection, as contact failure may occur. Such connectors are never placed on portable equipment, since vibration weakens the screw thread, and the contact may disappear altogether.
A cable with a BNC connector should not be tightened, as this may lead to loss of contact.
A special tool is used to firmly connect the cable to the compression connector. With it, the cable is inserted into the sleeve, which is then crimped. The connectors are made of brass and nickel-plated, which allows the use of such a connection in difficult weather conditions. Crimping the BNC connector provides a reliable connection, but the principle itself excludes reuse, since the sleeve is deformed.
Types of connectors
The simplest and cheapest coaxial connector is the BNC-F design. Such a connector consists of a sleeve, with an internal thread, and a nut. The role of the central pin is played by the core of the coaxial cable itself. Plastic insulation is removed from the wire and a sleeve is screwed onto the screen with force so that the central core protrudes 6-8 mm further than the edge of the nut. The resulting pin part is screwed onto the socket with a nut, while the cable core enters the contact hole.
Such connectors are often used to connect an antenna cable to TVs. This type of connector ensures the normal operation of the device at frequencies up to 2.0 GHz.
It is often necessary to connect a cable to a bayonet connector quickly and easily, without resorting to either soldering or crimping. For this purpose, a BNC connector with a block is perfect. This is a combined adapter, on one side of which there is the connector itself, and on the other side there is a REXANT type terminal block with two screw lamellas. Screw connection provides high reliability and contact quality.
The BNC-T connector is a splitter in which one high-frequency signal can be fed to two devices at the same time. The connector has the shape of the letter "T" and includes one male and two female parts. If the tee is used with only one device, then to match the wave resistance, a special plug is installed on the free outlet. It contains a 50 or 75 ohm resistor, depending on the type of cable.
The design of high-frequency connectors
The body of connectors designed to work with coaxial cables is usually made of brass and has a nickel plating. The cases of domestic SR connectors were also made of brass, they were coated with silver plating. The central pin (pin) of the connector is covered with silver or gold. Gold does not oxidize in any gas environment, so the contact is very reliable.
The washer, into which the pin is pressed, is made of various polymeric materials. It can be polyethylene, polystyrene or fluoroplastic (Teflon). Washers for solder connectors are always made only from Teflon, since other material softens from heat and the pin can lead to the side.
Application of BNC connectors
BNCconnectors are widely used in various areas of electronics:
- Reception and transmission of data in digital and analog interfaces
- Work in cellular communication systems
- Military and aerospace equipment
- Connecting CCTV cameras
- Control and measuring equipment
BNC connectors, when working with a 75 ohm cable, provide data exchange at a frequency of up to 2.0 GHz, and with a 50 ohm cable, the frequency can be doubled and reach 4.0 GHz.
Very often, such connectors are installed on video cameras. In order for the connection with the DVR to be reliable, choose a connector where the cable core is soldered to the central pin or use an adapter connector with a screw block. Almost all measuring instruments, including oscilloscopes, generators or signal spectrum analyzers, are connected via cable lines with BNC. Thus, you can organize a workplace for setting up or repairing any electronic equipment.
Conclusion
According to experts, the best connectors for transmitting a high-frequency signal are the Soviet-made connectors SR-50 and SR-75. They were developed and used for military equipment and have high reliability and minimal signal loss. They are silver-plated and are still available on radio markets.
