D-Subs Explained – Types of Connectors

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The D-subminiature is a versatile type of electrical connector.

Commonly called “DB connectors” or “D-subs,” these compact connectors take their name from their characteristic D-shaped shield, which protects both sides of the connector from mechanical and electromagnetic interference. The shield’s asymmetric shape also ensures that it only attaches to its corresponding connector in the correct orientation.

Inside the D-sub are two or more parallel rows of pins (in the plug) or jacks (in the socket) aligned to match the equivalent contacts in the other half of the connector. The pins or jacks frequently feature gold tips surrounded by a layer of insulation made from a variety of materials, including glass and PBT, a common insulating plastic.

Types of D-sub Connectors

We can differentiate D-sub connectors using several factors:

  • Number of pins or jacks. Letters A through E and their corresponding numbers indicate the number of contacts in the shell of each connector’s plug or socket. For example, the smallest common type of D-sub is the DE-9 (also DB-9), made up of a plug with nine pins matched to a socket with nine jacks. Some D-subs have “HD” added to their names, which indicates that they are high-density. HD D-subs feature a closer arrangement of pins and jacks within the shell.
  • Connection Methods. D-sub connectors vary in how they connect the contacts and the system circuitry. One of D-subs’ advantages is that they are well-suited for locking technology. Locking technology means that hardware keeps the plug and socket components in the mated position – usually by way of screws inserted into threaded holes attached to the metal shell of each part. Locked D-sub ports are more resistant to tampering and jostling than USB ports, HDMI, or Thunderbolts.
  • Connection Duration. D-sub ports also offer a range of connecting styles for other uses, such as crimping (easiest for temporary and at-home connections) and soldering (for more permanent connections).

Another subtype of D-sub connector is an ITT trademark called the microminiature-D or “micro-D.” Micro-D connectors are even smaller than standard D-subs, and you can find them in use almost exclusively for space-grade technology.

Advantages and Disadvantages of D-sub Connectors

When D-subs emerged in the 1950s, they were the most compact and effective connectors on the market. Personal computers featured D-sub ports for an array of external connections, including printers and Ethernet components. You can still find them at use in consumer electronics today, but they no longer dominate the market.

D-subs ports’ large size and unpredictable data transfer speeds have made them susceptible to replacement by newer technologies like USB ports for applications such as connecting personal computers and external devices. The USB port has largely replaced DE-9 for use in personal computers and memory components. Another disadvantage of D-sub is that its implementation requires an additional power source, as it contains lines for data and communication but not for power.

For some applications, D-sub connectors are still the best option:

  • DIY. Their flexible wiring and secure connection make D-subs ideal for do-it-yourself projects and bespoke electronics applications, where the range of connection options make frequent rewiring and fine-tuning easier.
  • Media applications. D-subs’ low cost and reliability make them useful for various types of media applications such as VGA (Video Graphics Array) connectors in television, gaming, and recording devices.
  • On-the-go usage. D-sub connectors are still more rugged than faster, more compact alternatives, making them a solid choice for portable recording where jostling is a risk.

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