Connectors are also called connectors, which are the most basic mechanical electrical connection devices that realize the detachable connection between circuit devices, components or assemblies. Commonly used connectors include various plugs (plug-ins), sockets (connectors) and terminal blocks, etc., whose main function is to transmit signals and currents, and to control the on or off of the connected circuit.

　　 There are many types of connectors, with different shapes, and a wide range of applications. Their performance is directly related to and affects the normal operation of the entire circuit system. Connectors can be divided into two types: one is used to connect electronic appliances and external equipment, and the other is used to connect electronic and electrical internal circuit boards and circuit boards, circuit boards and devices or components, etc. Connector. According to different forms, they can be divided into single-core plugs and sockets, two-core plugs and sockets, three-core plugs and sockets, coaxial plugs and sockets, and multi-pole plugs and sockets. According to different purposes, it can be divided into audio, video plugs and sockets, printed circuit board sockets, power plugs and sockets, integrated circuit sockets, tube sockets, binding posts, terminals and connectors.

　　(1) terminal

Terminals are often used for the connection between electronic appliances and external equipment. It can be divided into two forms: one is the ordinary terminal on the left side of the figure, which is characterized by directly pressing the connector of the connecting wire through the fastening nut. In the hole; the other is the banana plug and socket on the right side of the picture, which is characterized by soldering the connecting wire to the plug and then plugging it together with the socket. Because the spring on the plug is shaped like a banana, the terminal is also called "banana plug, socket".

　　(2) terminal block

The terminal block is mainly used for the connection between the circuit board and the circuit board of the electronic appliance, the circuit board and the device or component. It can be divided into two forms: circuit board welding type and bidirectional wiring type (pure wiring type): circuit board welding One end of the type is made into a soldering foot, which can directly solder the terminal block on the circuit board, and the other end is used to fasten the connector of the connecting wire in the wiring hole by a fastening screw.

　　(3) Audio plug, socket (hole)

　　 This type of connector is mainly divided into two-pin plugs and sockets and three-pin plugs and sockets. It can easily connect or disconnect audio equipment and external equipment (such as earphones, microphones, etc.) at any time. As the name suggests, two-pin plugs and sockets can be plugged into two-wire devices at the same time, suitable for transmitting single-channel audio signals, and three-pin plugs and sockets can be plugged into three-wire devices at the same time, suitable for transmitting stereo (two-channel) audio signals .

　　(4) Low-voltage power plugs and sockets

　　 This type of connector is improved on the basis of audio two-pin plugs and sockets, and is specially used for plugging in various small electronic devices and supporting external power supplies. The biggest difference from audio two-core plugs and sockets is that the plug is tubular in shape, and the inner and outer sides are used as the two electrodes of the power supply. This fundamentally avoids the unavoidable occurrence of audio two-core plugs when they are inserted into the socket. Instantaneous short circuit (referring to the two poles of the plug); the socket electrode matches the tubular electrode of the plug, and it also has an automatic switch function, which can automatically cut off the power supply in the machine when the external power plug is inserted into the socket.

　　(5) AC power plug and socket

　　 This type of connector is divided into two categories: two-pole power plug and socket and three-pole power plug and socket. They are used to transmit 220V alternating current in various electronic and electrical equipment. It should be pointed out that there are many types and specifications of this kind of connectors. As far as machine-mounted sockets are concerned, some sockets are power output sockets that can be inserted into the plugs of ordinary household appliances; but most sockets are power input sockets and cannot When inserting the ordinary plug with exposed electrode, only the matched non-electrode exposed plug (namely output plug) can be inserted.

　　(6) Circuit board dedicated connector

　　 This type of connector consists of a socket that can be directly welded on the circuit board and a plug that is connected to a transmission wire. It has a variety of specifications and can be divided into two categories: single-lead and multi-lead. This type of connector is characterized by flexible use, small footprint, and convenient plug-in and pull-out.

　　(7)Printed circuit board socket

　　 The matching "plug" is actually an application circuit board. The socket is widely used in various instruments, meters and computers. It has many specifications and can be divided into two categories: single row (used for single-sided printed circuit boards) and double row (used for double-sided printed circuit boards) , There are many kinds of pin numbers, and there are many specifications of pin pitch. Such sockets are generally provided with positioning grooves, and some are also provided with an opening key and a locking key.

　　(8) IC socket

　　 The socket is designed for use with integrated circuits. . In addition to the most common dual-in-line package, this special socket also has multiple package forms such as single-in-line and quad-in-line, and its specific specifications are compatible with the corresponding integrated circuits. In actual application, the socket is directly soldered on the printed circuit board, and the integrated circuit is directly inserted into the socket through its pins. The advantage of this is that there is no need to solder the integrated circuit on the printed circuit board, which brings great convenience to the maintenance and replacement of the integrated circuit.

　　(9) USB interface

　　 Because the USB interface has the advantages of fast data transmission speed, support for hot plugging, flexible connection, independent power supply, etc., in recent years, it has been widely used in various digital products.

　　 There are many types of connectors with different functions, and sometimes the parameter items that reflect product performance are not exactly the same. However, the following basic parameters have commonalities and users must master them.