What are the Different Types of Circular Connectors?

Circular connectors, or circular interconnects, are cylindrical, multi-pin electrical connectors containing contacts that transmit both data and power. Canon (now ITT Tech Solutions) first created circular connectors in the 1930s for military aircraft, but they can now be found in industrial applications, medical devices, and other environments where reliability is crucial, such as industrial applications and medical devices.

Circular connectors feature a plastic or metal shell surrounding the contacts, which are embedded in insulating material to maintain their alignment. These terminals are paired with a connector cable and makes them very resistant to environmental interference and accidental decoupling.

Connectors can be distinguished by their number of pins (usually three, six, or eight per terminal) and by their size, manufacturing specifications, attachment angles, and methods of connection and disconnection.

 A “standard” connector refers to a connector whose design conforms to either German or American military standards. American standards are MIL-Spec Connectors and are designed according to the best practices for military and aerospace applications. They are rugged, ideal for high-impact use, and are highly resistant to environmental conditions. Some MIL connectors are air and watertight thanks to an epoxy seal around the terminal. The German standard is DIN Spec Connector (Deutsches Institut fur Normung). DIN standards include high-frequency capability and hallmark features like a protective metal shell and notched, round terminations. Microminiature and nanominiature connectors featuring smaller pin and jack diameters also exist and have more narrowly spaced contacts. This construction helps save surface space across the face of the terminal, and it reduces the connector’s added weight to the component.

Another consideration for circular connectors components is there style of termination. The type of termination chosen determines the nature of the connections between electrical contacts in each of the connector’s components. Options vary regarding cost, ease of connection and disconnection, and resistance to tampering, wear, and environmental damage. Terminal options include:

  • Insulation displacement, where the pins in the plug pierce or push aside insulation around the corresponding jacks in the socket, making contact and forming an electrical connection.
  • Soldering: using an intervening metal with a low melting point, the metal touches both contacts to form a permanent corridor.
  • Screws or lugs: External hardware adheres to threaded (screws) or unthreaded (plugs) holes in the protective shield around each terminal to hold the connection in place.
  • Crimping: A contact barrel compresses around the conductor to complete the electrical connection.
  • Wire wrap: wires connected to the socket side of the connector attached to the other terminal. The wires wrap around the plug’s jacks, so an exposed segment touches the jack.


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