Barrel connector
A barrel connector or low-voltage connector is an at least two- pin coaxial connector with a cavity, which is mostly used to power devices with direct voltage (only then also referred to as a DC connector ) or alternating voltage from an external power supply unit , often also for charging batteries built into the devices .
General
Typical applications are portable electrical devices of all kinds, power tools and toys. Hollow plugs are suitable for operation with safe extra-low voltage , have a well-protected internal contact and, compared to coaxial jack plugs, the advantage that there is no short circuit when slipping out of the socket.
function
An external spring in the socket presses the plug against the center pin. With this type of construction, the effective contact area is only a fraction of what is mechanically possible. Since a smooth plug slips out easily, some have a bulge or a notch that snaps into a specially made socket. In the case of a plug for higher currents, the center pin is split as a double or quadruple spring and the socket contacts on the outer surface are also made multiple.
hazards
Incorrect voltage, incorrect power or incorrect polarity can destroy the device and / or the power supply unit. The devices have information on voltage, current and connection assignment as a pictogram .
standardization
There are standards that describe the mechanical structure, but not the voltages and polarity .
A common norm for older devices was:
- 5.5 mm / 2.5 mm (outer / inner diameter) and
- 5.5mm / 2.1mm
There are now many other standards, with many manufacturers often introducing proprietary standards.
Other common sizes are e.g. B .:
- 7.9 mm / 5.6 mm (e.g. Lenovo notebooks)
- 6.3 mm / 3.0 mm (printers, notebooks)
- 5.5 mm / 3.3 mm (e.g. for Gigaset cordless phones)
- 5.0 mm / 2.1 mm
- 4.8 mm / 1.7 mm (especially with Hewlett-Packard notebooks)
- 4.0 mm / 1.7 mm (for TomTom Rider 2)
- 3.5 mm / 1.35 mm (e.g. Nokia old)
- 2.5 mm / 0.7 mm
- 2.35mm / 0.7mm
- 2.0 mm / <0.8 mm (e.g. Nokia flat devices)
Occasionally, power packs also have jack plugs instead of barrel plugs with a diameter of 3.5 or 2.5 mm.
Different types of barrel connectors, an adapter set below
Jack and barrel adapter for a universal car power supply
Barrel plug on a SNES power supply
5 mm panel sockets. Pin diameter
2.5 mm on the left,
2.1 mm on the right
Special designs
Notebooks have often used proprietary special forms. Often the center pin is ring-shaped and the connector has a center pin , often to signal the power of the power supply.
Some barrel connectors have a resilient insulating sleeve for the external contact. This type is intended for use in vehicles where the extra-low voltage is not electrically isolated. A short circuit of the external contact with the body can lead to undesired earth currents or even to a short circuit (if the positive pole is outside or - in the case of historical vehicles - positive to the body).
One type of barrel connector that is often found on Japanese electronics is the EIAJ connector .