Banana connector

A 4-mm -clip ( colloquially banana plug ) is a primary laboratories for electric -designed connectors for low to medium electrical currents (usually up to 16 A ) and low voltage applications. It owes its name to the banana shape of the leaf spring element, with which the plug relatively fixed, but still detached without tools, properly seated in the socket. The banana plug (also called telephone jack ) must have a diameter of 4 mm, of the connector by the spring element is variable in its diameter to several tenths of a millimeter.

Use

The plug still in use today was developed in 1924 by the company Hirschmann GmbH to replace the hitherto usual experimental setups spring clamps and threaded connections. Although similar connections already existed before ( with different diameters and lengths ), the product offered by its overall design (contact, suspension and isolation, then still Bakelite ) such advantages that it is a " de facto standard " established laboratory technology.

Previously, many compounds have been realized with screw in laboratory technology, the very careful editing needed. As a counterpart to the banana plugs on the other hand, a simple 4- mm hole into a metal block.

For signal transmission banana plugs are due to the reliable multi-point connection between plug and jack quite suitable, but have the common test lead with banana plugs had no shielding against interference.

Hazards

Banana plugs fit into a wall outlet, if they are not child-resistant.

To avoid electrical accidents are there for the taking of power by means of banana plugs special safety plug with insulated safety sockets.

In medical banana plugs should not be used due to lack of reverse polarity protection. Regardless of this type of connector is used for example in ECG devices for the connection cable of the EEG electrodes on the body.

4- mm - plug system

Banana plugs are available in many versions. For laboratory setups important is almost always existing clutch or the transverse hole in the plug, which quickly additional connectors can be connected to a specific point in the experimental setup.

An important variant of the so-called spring wire plug. Here, instead of the banana-shaped curved leaf spring a number ( usually six) of resilient wires available. Most of these are held together with a spine and a cap. Also widespread are connectors with an annular spring element. These are also available in gold plated.

Furthermore, there are banana plugs that hold an advanced with spring plastic socket to the plug and a plastic cap. You are limited safe to touch and therefore can also be used for mains voltage.

This is also available in versions with rigid insulating sleeve and are thus finger-safe.

Also known as speaker connectors on amplifiers and speakers banana jacks are often used. These are usually slightly larger, and the insulating body is designed as screw, so that the speaker wire to optimize the contact resistance can be clamped directly. Also, on some instruments one finds this design.

All these designs are for interconnection.

Other diameters

For laboratory setups with low voltages and very many sockets, but there is also a plug-in system with 2 mm socket diameter. Here plugs are almost always used with kranzförmigem spring element.

In Modellbahnbau interlock various connector systems with 2.4 mm to 2.6 mm tube diameter are common. Due to the lower production expenses connectors are mostly used here with slotted contact, who in common with the classic banana plugs only the transverse hole.

For higher currents, there are single-pole connector system with 6 mm nominal diameter. They can withstand continuous currents of about 80 amps and are also available in lockable version.

In multimeters protection against accidental contact is realized by plastic sleeves that protrude forward a piece in some radial distance and immerse yourself in a cylindrical deep groove around the bush.