D-sub

D-subminiature or D-sub is a common type of electric connector used particularly in the Ordinateur S.

Description and nomenclature

It contains two parallel lines, or more, of pins, or casings, usually surrounded by a metal shield in the shape of D which protects from the electromagnetic interferences. The shape in D guarantees a correct orientation. The part containing the contact tags is called the plug connector, whereas that containing the casings of contacts is called the connector female. The shield of the socket adapts inside the plug. The shields are connected to braidings surrounding the cables (when braided cables are used), thus creating a continuous electromagnetic screen covering the cables and the connectors.

The D-sub connectors were invented by Canon, part of ITT. The system of classification of Canon uses D like prefixes for the whole series, followed by a letter indicating the size of hull (A=15 pins, B=25 pins, C=37 pins, D=50 pins, E=9 pins), followed real number of pins, then kind (M=mâle, F=femelle). For example, DB25M means D-sub with hull of size of 25 pins and 25 contacts male. Canon also produced of D-sub with coaxial insertions or to strong intensity which replaced several normal and smaller pins.

It seems that many people, not knowing the significance of the letter B like cut hull, started to call all the connectors of this kind “dB” instead of “D”. When the port series of the PC started to use connectors with 9 pins, those were often called “DB-9” instead of DE-9. It is now common to see connectors DE-9 sold under the name of “dB”.

The connectors are now defined by an international standard, DIN 41652.

Typical applications

The broadest application of D-sub is in the communications series RS-232. Bonds RS-232 in the beginning employed of D-sub 25 pins, but for much of applications the least useful signals were omitted, allowing the use of D-sub 9 pins. On catches GCV, 9 pins and 25 pins are used for the ports series RS-232 and of the casings 25 pins are used for the wearing of printers (parallel) Centronics, although all the latter are now replaced by connectors PS/2 and ports USB.

At the end of the Years 1970 and at the beginning of the Years 1980, the DE9M were almost connectors of universal controllers on the video Game consoles and the personal computers. They became a standard de facto, by the use of these ports in the game console Atari 2600 and the family of the computers 8 bits of Atari. Moreover, the casings 9 pins were used in the past for the numerical ports of video out color PC (CGA, EGA), but also for the analogical video (Connecteur VGA used on the charts VGA and more). The latter were replaced by the casings 15 pins with high density, which have three lines of five contacts in the space which was previously occupied by two lines (one of five contacts and one of four contacts).

The complete range of the D-subs connectors also includes:

the 15 pins (two lines of 7 and 8), used for the analogical joysticks on the PC;
the 37 pins (two lines of 18 and of 19)
the 50 pins (two lines of 17 and one central line of 16)

The two last are used in the industrial products.

Types and alternatives

There exist at least three types of D-subs connectors. They are differentiated by the method employed to attach wire to the contacts: to weld, with displacement of insulator or to crimp.

The solder contacts have a cavity in which the stripped wire is inserted and welded.

The contacts with displacement of insulator are conceived for the automated assembly. A flat cable is in a hurry against the contacts whose back is in the shape of fork, which then bores insulator of all wire simultaneously.

The crimp contacts are cabled while inserting a stripped end of wire in a cavity into the back of the contact. One then crushes the cavity using a grip to be crimped. The contact is then inserted in the connector, where it is found blocked. Various pins can be removed later with a tool inserted into the back of the connector. This “disconnection by the back” is useful when the pins of the peripheral are damaged.

A smaller type of connector is derived from D-sub, it makes about one the third of the size on the surface and half in length, it is called microminiature D (or Micro D which is a registered trademark of Canon ITT Industries ). This connector is used in the industrial products or medical and the aerospace one (reduction of weight). Some manufacturers make the nano-D connectors, which have a size half of the microphone-D. There exist alternatives of all these types, which combine on the same connector of the electrical or coaxial contacts.

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