A complete collection of weak current knowledge necessary for novice decorators.

Weak current generally refers to DC circuits or audio, video lines, network lines and telephone lines, and the DC voltage is generally within 36V. Telephone, computer, TV signal input (cable TV line), audio equipment (output line) and other household appliances are all weak current electrical equipment. Weak is relative to strong electricity. Today, I have summarized a comprehensive knowledge of weak current. The encyclopedia of weak current knowledge includes what weak current is, what it is used for, the difference between weak current and strong current, the function and application of weak current and so on. I believe that after reading the following introduction, you will benefit a lot.

What is weak current?

Weak current generally refers to DC circuits or audio, video lines, network lines and telephone lines, and the DC voltage is generally within 36V. Telephone, computer, TV signal input (cable TV line), audio equipment (output line) and other electrical appliances in household appliances are all weak current electrical equipment.

What is a weak box?

As the name implies, the weak box is the concentrated box of weak current lines, which is generally used in modern home decoration, such as network cable, telephone line, computer monitor, USB cable, VGA, color difference and antenna of TV. Moreover, if these things are not placed neatly, they will be a mass of lines, which will be chaotic and appear disharmonious, and will also affect cleanliness. In a word, the weak box is used to hold these devices and arrange wires.

What is a weak current cable?

Weak current cables refer to cables used for secure communication, electrical equipment and related weak current transmission. The brands of weak current cables are Kanami, Nutrick, Yu Ling, Tiancheng, Lianjiaxiang, Akihabara, Diyi and Yizhou.

Weak current classification

There are two main types of weak electricity in buildings:

One is low-voltage electric energy such as safe voltage grade and control voltage specified by the state, which is divided into AC and DC. Alternating current below 36V and DC below 24V, such as 24V DC control power supply or emergency lighting standby power supply.

The other is information sources including sound, images and data, such as telephone, television and computer information.

Intelligent system is composed of building equipment automatic control system (BA), safety prevention system (SA), communication network system (CA), office automation system (OA), automatic fire alarm and fire fighting linkage system (FA), which is a comprehensive system integrating centralized monitoring, control and management. All kinds of data collection, control, management, communication control or network system lines in the home are called intelligent lines (that is, weak current in home decoration).

The difference between weak current and strong current

The main difference between strong electricity and weak electricity is the difference in use. Strong electricity is used as power supply and weak electricity is used for information transmission. Specifically, it is roughly as follows:

(1) AC frequency is different: the frequency of strong electricity is generally 50Hz, which refers to the frequency of industrial electricity; The frequency of weak current is often high frequency or ultra-high frequency, which is measured by KHz and MHz.

(2) Different transmission modes: high voltage is transmitted by transmission lines, and weak current is transmitted by wired or wireless. Radio is transmitted by electromagnetic waves.

(3) The magnitude of power, voltage and current are different: strong electric power is measured in KW (kilowatt) and MW (megawatt), voltage in V (volt) and KV (kilovolt), and current in A (ampere) and kA (kiloampere); Weak current is measured in W (Watt) and mW (Milliwatt), voltage in V (Volt) and mV (Millivolt), and current in mA (mA) and uA (Microampere), so its circuit can be composed of printed circuit or integrated circuit.

Of course, there are also high-frequency (several hundred KHz) and intermediate-frequency devices in high voltage, but the voltage is higher and the current is larger. Another example is flashlights and electric razors. Although the voltage is very low, the power and current are very small, they are still strong. Due to the development of modern technology, weak current has penetrated into high voltage fields, such as power electronic devices and wireless remote control. But these can only be regarded as the weak current control part of high voltage, which is different from charged high voltage.

Function and application of weak current

According to the intensity of power transmission, power applications can be divided into two categories: strong electricity and weak electricity. Building and building electricity generally refers to high-voltage alternating current above 220 V and 50 Hz. It mainly provides people with electric energy and converts it into other energy sources, such as air conditioning electricity, lighting electricity, power electricity and so on.

Generally speaking, weak current system engineering refers to the second application. Mainly includes: 1, TV signal engineering, such as TV monitoring system and cable TV. 2. Communication engineering, such as telephone. 3, intelligent fire engineering. 4. Sound reinforcement and sound engineering, such as community background music broadcasting and building background music. 5, integrated wiring engineering, mainly used for computer networks.

Weak current system is mainly aimed at buildings, including buildings, residential areas, airports, docks, railways, highways and so on.

Common weak current systems include: ccTV monitoring system, burglar alarm system, entrance guard system, electronic patrol system, parking lot management system, visual intercom system, home intelligent system and security system, background music system, LED display system, plasma splicing screen system, DLP large screen system, three-meter CC system, building automatic control system, lightning protection and grounding system, paging intercom and professional intercom system, weak current pipeline system, UPS uninterrupted power supply system, Computer room system, integrated wiring system, computer local area network system, property management system, multifunctional conference room system, cable TV system, satellite TV system, satellite communication system, fire protection system, telephone communication system, hotel management system, video-on-demand system, etc.

Weak current wiring

It is a matter of * * to enjoy Internet, telephone, cable TV and other resources. It is best to have all three interfaces in the main room. Frequency-dividing equipment for Internet, telephone and cable TV families generally goes in and out in four directions (many of them are expensive). If it is a two-bedroom apartment, you can generally leave internet, telephone and TV interfaces in the living room, master bedroom and second bedroom, TV interfaces in the restaurant and telephone interfaces in the bathroom. If there are more rooms, you can choose to book; You can also run all the wires out first and put them in the weak current distribution box. If necessary, the plugs leading to each room can be replaced. Audio and video are different. Although it can be shared in frequency division, it can only provide signals for one terminal at home at the same time.

In order to meet the requirements of * * * sharing and intercommunication, weak current wiring must adopt frequency division or switching equipment. The switching equipment inside and outside the network is a router (for local area network) or a modem (for ADSL), that is, the weak current line of cat should adopt star wiring, radiating from the switching and frequency division equipment to each port. Considering the simple wiring construction and convenient maintenance, it is best to put all kinds of equipment in the same place.

Special plugs and sockets should be used for weak current wiring, and RJ45 heads (also called ampere heads/crystal heads) and RJ45 head panels and modules should be used for network cables; Telephone lines use RJ 1 1 connectors and corresponding sockets; RJ45 head should be equipped with special wire cutters and steel pestle. When wiring, the cable in the box should have a head of about 10 cm. If there is an error when connecting the plug, it can be recovered.