Whilst technically inaccurate, electrical connectors can be viewed as a type of adapter to convert between two connection methods, which are permanently connected at one end and (usually) detachable at the other end.
Plug and socket connectors Plug and socket connectors are usually made up of a male
plug (typically pin contacts) and a female
socket (typically receptacle contacts). Often, but not always, sockets are permanently fixed to a device as in a chassis connector , and plugs are attached to a cable. Plugs generally have one or more pins or prongs that are inserted into openings in the mating socket. The connection between the mating metal parts must be sufficiently tight to make a good electrical connection and complete the circuit. An alternative type of plug and socket connection uses
hyperboloid contacts, which makes a more reliable electrical connection. When working with multi-pin connectors, it is helpful to have a
pinout diagram to identify the wire or circuit node connected to each pin. Some connector styles may combine pin and socket connection types in a single unit, referred to as a
hermaphroditic connector. These connectors includes mating with both male and female aspects, involving complementary paired identical parts each containing both protrusions and indentations. These mating surfaces are mounted into identical fittings that freely mate with any other, without regard for gender (provided that the size and type match). Sometimes both ends of a cable are terminated with the same gender of connector, as in many
Ethernet patch cables. In other applications the two ends are terminated differently, either with male and female of the same connector (as in an
extension cord), or with incompatible connectors, which is sometimes called an
adapter cable. Plugs and sockets are widely used in various connector systems including blade connectors,
breadboards,
XLR connectors,
car power outlets,
banana connectors, and
phone connectors.
Jacks and plugs A
jack is a connector that installs on the surface of a bulkhead or enclosure, and mates with its reciprocal, the
plug. According to the
American Society of Mechanical Engineers, the stationary (more fixed) connector of a pair is classified as a
jack (denoted J), usually attached to a piece of equipment as in a chassis-mount or panel-mount connector. The movable (less fixed) connector is classified as a
plug (denoted P), This convention is currently defined in ASME Y14.44-2008, which supersedes
IEEE 200-1975, which in turn derives from the long-withdrawn MIL-STD-16 (from the 1950s), highlighting the heritage of this connector naming convention. Crimped contacts are permanent (i.e. the connectors and wire ends cannot be reused).
Crimped plug-and-socket connectors can be classified as
rear release or
front release. This relates to the side of the connector where the pins are anchored: When creating soldered connections, it is possible to melt the
dielectric between pins or wires. This can cause problems because the thermal conductivity of metals causes heat to quickly distribute through the cable and connector, and when this heat melts plastic dielectric, it can cause
short circuits or "flared" (conical) insulation.
Insulation-displacement connectors Since stripping insulation from wires is time-consuming, many connectors intended for rapid assembly use
insulation-displacement connectors which cut the insulation as the wire is inserted. applications for additions to existing wiring. A common example is the multi-conductor flat ribbon cable used in computer disk drives; to terminate each of the many (approximately 40) wires individually would be slow and error-prone, but an insulation displacement connector can terminate all the wires in a single action. Another very common use is so-called
punch-down blocks used for terminating
unshielded twisted pair wiring. s on a
bi-amplified loudspeaker
Binding posts Binding posts are a single-wire connection method, where stripped wire is screwed or clamped to a metal electrode. Such connectors are frequently used in
electronic test equipment and audio. Many binding posts also accept a
banana plug.
Screw terminals Screw connections are frequently used for semi-permanent wiring and connections inside devices, due to their simple but reliable construction. The basic principle of all screw terminals involves the tip of a bolt clamping onto a stripped conductor. They can be used to join multiple conductors, to connect wires to a
printed circuit board, or to terminate a cable into a plug or socket. The clamping screw may act in the longitudinal axis (parallel to the wire) or the transverse axis (perpendicular to the wire), or both. Some disadvantages are that connecting wires is more difficult than simply plugging in a cable, and screw terminals are generally not very well protected from contact with persons or foreign conducting materials.
Terminal blocks (also called terminal
boards or
strips) provide a convenient means of connecting
individual electrical wires without a splice or physically joining the ends. Since terminal blocks are readily available for a wide range of wire sizes and terminal quantity, they are one of the most flexible types of electrical connector available. One type of terminal block accepts wires that are prepared only by stripping a short length of
insulation from the end. Another type, often called
barrier strips, accepts wires that have ring or spade terminal
lugs crimped onto the wires.
Printed circuit board (PCB) mounted
screw terminals let individual wires connect to a PCB through leads soldered to the board.
Ring and spade connectors The connectors in the top row of the image are known as
ring terminals and
spade terminals (sometimes called fork or split ring terminals). Electrical contact is made by the flat surface of the ring or spade, while mechanically they are attached by passing a screw or bolt through them. The spade terminal form factor facilitates connections since the screw or bolt can be left partially screwed in as the spade terminal is removed or attached. Their sizes can be determined by the
gauge of the conducting wire, and the interior and exterior diameters. In the case of insulated crimp connectors, the crimped area lies under an insulating sleeve through which the pressing force acts. During crimping, the extended end of this insulating sleeve is simultaneously pressed around the insulated area of the cable, creating strain relief. The insulating sleeve of insulated connectors has a color that indicates the wire's
cross-section area. Colors are standardized according to DIN 46245: • Red for cross-section areas from 0.5 to 1 mm² • Blue for cross-section areas from 1.5 to 2.5 mm² • Yellow for cross-section areas over 4 to 6 mm²
Blade connectors A
blade connector is a type of single wire, plug-and-socket connection device using a flat conductive blade (plug) that is inserted into a receptacle. Wires are typically attached to male or female blade connector terminals by either
crimping or
soldering. Insulated and uninsulated varieties are available. In some cases the blade is an integral manufactured part of a component (such as a switch or a speaker unit), and the reciprocal connector terminal is pushed onto the device's connector terminal.
Other connection methods •
Alligator and Crocodile clips – conductive clamps used for temporary connections, e.g.
jumper cables •
Board to board connectors – e.g.
card-edge connectors or
FPGA mezzanine connectors •
Twist-on wire connectors (e.g. wire nuts) – used in
low-voltage power circuits for wires up to about 10 AWG •
Wire wrapping – used in older circuit boards ==See also==