History and Design of Banana Connector
– Invented by Richard Hirschmann in 1924
– Hirschmann was granted a patent in Germany in 1929
– General Radio Company introduced the banana plug in the United States in 1924
– Various banana plug products shown in a September 1928 catalog
– Prices listed in a July 1928 newsletter
– Original plug consists of a cylindrical metal pin about 20 millimeters long
– Other sizes have emerged, such as 15 millimeters pins in the US
– Pin diameter is nominally 4 millimeters
– Banana plug has lengthwise springs that bulge outwards slightly
– Rear end of the plug often has a 4mm hole drilled in it for stacking
Derived Plugs and Miniature Banana Connectors
– PL-259 plug is widely used as a high frequency cable connector
– Derived plugs combine two or more banana plugs in a common plastic housing
– Double banana plug consists of two banana plugs spaced 3/4 inch apart
– Housing may allow connection of individual wires or a coaxial cable
– Tab located on one side of the dual banana plug denotes the ground or negative side
– Miniature versions of the banana connector have been introduced
– One type is 2.6mm in diameter and about one third the length of the standard connector
– Another miniature type is the 2mm banana connector
– Multiple miniature banana connectors are usually spaced on 1/2 inch centers
– Available in various plug contact styles and encased versions for high voltage applications
Pin Tip Jacks
– Pin tip plug and matching pin tip jack is a closely related design to the banana plug
– Plug design resembles the banana plug without the spring on the male pin
– Relies on spring action in the female jack or tightly machined tolerances for good contact
– Male pin diameter is 2mm
– Used where maximum density of connectors was desired or where a compact connector was needed
Wander Plug
– Widely used in the UK and elsewhere until the 1960s
– Used for connecting separate HT and grid bias batteries in early battery-powered valve radios
– Also used for antenna and earth connections and external loudspeakers in both mains and battery-powered valve radios
– Wander plug had short bell-mouthed brass tube battery terminals
– Pin end of the wander plug was split to provide elasticity and secure fit in the socket
Electrical Safety and Use of Sheathed Plugs and Sockets
– Quality banana plugs and cables are typically rated for 30V at 15A
– Cheaper cables may have downsides such as lower quality plugs, smaller diameter wire, lower strand count wire, thinner insulation, or lower quality insulation
– Unsheathed banana connectors are not usually rated for mains voltage
– Exposed banana plugs or sockets can present a shock hazard if connected to an energized source
– Partially inserted plugs can also pose a risk of accidental contact
– Sheathed plugs and sockets are used where electrical safety is an issue
– These plugs have fixed or sliding sheaths to protect the user from accidental contact with live conductors
– Sheaths of the plug and socket overlap fully when inserted, ensuring no live metal is exposed
– Multimeter test leads and other measurement equipment often use sheathed banana plugs
– Test lead wires must be made with insulation rated for higher voltages
– In most European countries, the standard mains power receptacle can physically accept banana plugs, leading to a risk of electrical shock
– Audio amplifiers and loudspeakers in the European Union must have removable plastic plugs in their sockets to mitigate this risk
– The UK was included in the prohibition, even though such mains sockets were not used there Source: https://en.wikipedia.org/wiki/Banana_connector
A banana connector (commonly banana plug for the male, banana socket or banana jack for the female) is a single-wire (one conductor) electrical connector used for joining wires to equipment. The term 4 mm connector is also used, especially in Europe, although not all banana connectors will mate with 4 mm parts, and 2 mm banana connectors exist. Various styles of banana plug contacts exist, all based on the concept of spring metal applying outward force into the unsprung cylindrical jack to produce a snug fit with good electrical conductivity. Common types include: a solid pin split lengthwise and splayed slightly, a tip of four leaf springs, a cylinder with a single leaf spring on one side, a bundle of stiff wire, a central pin surrounded by a multiple-slit cylinder with a central bulge, or simple sheet spring metal rolled into a nearly complete cylinder. The plugs are frequently used to terminate patch cords for electronic test equipment such as laboratory power supply units, while sheathed banana plugs are common on multimeter probe leads.
