DC connector
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Connectors for supplying direct current (DC) power are poorly standardized compared to domestic AC power plugs and sockets. DC plug is a common name used for one common type of cylindrical two-conductor plug available in a range of sizes and used to power small pieces of electronic equipment. It is also used to describe some older multi-pin plugs.
Several competing standards exist for DC plugs, and in some cases incompatible plugs will fit together, or can be made to fit, possibly damaging equipment if:
- the voltage is wrong
- the polarity is wrong
- current ratings are exceeded
- power supply filtering or stability is inadequate for the equipment being powered
- non-matching connectors are forced together.
[edit] Cylindrical types
- For more details on this topic, see Coaxial DC Power Connectors.
Also known as barrel connectors, concentric barrel connectors or tip connectors, small cylindrical connectors come in an enormous variety of sizes.
The intended use of these plugs is on the cable connected to a power supply. The matching jack or socket is then mounted in the equipment to be powered. Some of these jacks contain a normally closed contact, which can be used to disconnect internal batteries whenever the power supply is connected, avoiding the risk of battery leakage or explosion posed by incorrect recharging of the batteries.
Cylindrical plugs generally have an insulated tip constructed to accept insertion of a pin. The outer body of the plug is one contact, most often but not always the negative side of the supply. A pin mounted in the socket makes contact with a second internal contact. The outer plug contact is often called the sleeve, and the inner the tip, although the tip itself is actually non-conductive.
There are a wide variety of different sizes and designs for these power connectors, and many appear quite similar to each other yet are not quite mechanically or electrically compatible. In addition to a plethora of generic designs (whose original designer is unknown) there are at least two different national standards—EIAJ in Japan and DIN in Germany, plus the JSBP connector used on some laptop computers. The Japanese EIAJ standard includes five different sizes, with each supporting a specified range of voltages. Most of the other coaxial DC power connectors have no specified voltage asociation, however.
The most common plugs are 5.5 mm in outside diameter (OD) and 9.5 mm in length. Two pin sizes are common in the jacks for this size plug body, 2.1 mm and 2.5 mm, and the plugs should ideally match. Generic plugs are often named for the pin diameter they are designed to take, so these types will be seen described as 2.1 mm DC plugs and 2.5 mm DC plugs respectively. These two sizes are easily confused unless seen together.
Contact ratings vary from unspecified (and probably less than 1 A in practice) up to 5 A ,with 2 A typical. Voltage is again often unspecified, up to 48 V with 12 V typical. The smaller types usually have lower ratings, both for current and voltage.
Also, confusingly these plugs are occasionally used for AC power supply applications, such as with the Nintendo Entertainment System and SNES video game consoles, which used these for 9 or 10 V AC power (depending on region).
[edit] Snap and Lock DC Power Connectors
These connectors look similar to Mini-DIN connectors, but have either 3 or 4 thicker pins and do not mate with any of the Mini-DIN connectors. They can usually be identified by an engraved symbol on the backs of the plug, consisting of two wide arrows pointing in opposite directions, but parallel to each other, or sometimes one wide arrow inside a box, pointing towards the end of the male connector. See [1] for pin configuration.
One manufacturer is KYCON, Inc.
Access Communications Snap and Lock plug information
[edit] Molex Connector
- For more details on this topic, see Molex connector.
The connector design most commonly called Molex connector has frequently been used to supply DC power, most frequently on personal computers, for supplying power to drives and other peripherals.
[edit] Mini IEC Connector
[edit] Tamiya Connector
- Commonly used on radio-control (toy) vehicle battery packs and chargers.
- [2] shows converter cables for connectors commonly used in the RC community.
[edit] Deans Connectors
- Popular with higher-end radio-control vehicle battery packs and chargers.
- W.S. Deans Web site
[edit] JST RCY Connector
- Also known in RC circles as the BEC connector, or the P connector.
[edit] Locking Molex Connector
- Available in 3, 4, and 6 terminal configurations. [3]
[edit] Anderson Powerpole connectors
The Anderson Powerpole has been adopted by the amateur radio community as their standard 12-volt DC power connector for everything from radios to accessories. It is a bit more expensive than the older “standards” of the 2-wire trailer plug and Molex connector, but provides a more reliable electrical connection (both mechanically and electrically) and is easier to adapt to a wider range of wire gauges. Powerpole connectors are physically and electrically hermaphroditic, thus avoiding the need to worry about which end is the plug and which the socket, or which end has the correct polarity, as is the case with the physically but not electrically hermaphroditic 2-wire trailer plug.
For use in amateur radio, the community has adopted a standard polarity for assembling the Singlepole connectors, using one red and one black housing, as well as a mnemonic for remembering the arrangement: Red Right—Tongue Top. Before this polarity standard was adopted, some amateur radio groups had chosen the opposite polarity, so it is wise to double-check the polarity before blindly plugging devices together.
Although many sizes of the Powerpoles are available, the size most commonly used is the 15/30/45 amp variety. These sizes all use the same plastic housing, differing only in the metal contact inserted into the housing (selected based on the current need and wire size). Larger Powerpole connectors (the SB/Multipole series) with 2 or 3 contacts in one molded housing are commonly used in various industrial settings, including as a battery connection for some UPS devices, removable truck/Jeep winches, many electric forklifts, and other electric powered vehicles.
For the larger Multipole design, each color is keyed so as to mate only with a like colored connector, and Anderson publishes a list of recommended voltages for each color: [4]
- 12V: Yellow
- 18V: Orange
- 24V: Red
- 36V: Gray
- 48V: Blue
- 72V: Green
- 80V: Black
- 96V: Brown
- 120V: Purple
- 144V: White
Some manufacturers have ignored this color coding recommendation. One should always test the connection with a voltmeter if unsure. For example, winch manufacturer Warn uses a red housing for its winches, even though they are powered by 12 V DC, not 24 V DC.
The connectors are also starting to be used by Radio Control hobbists.
This connector design was created by Anderson, but the patent on its design has apparently lapsed, and there are be other manufacturers of this connector now, including AMP and Sermos.
[edit] Cigar lighter sockets and plugs
The car cigarette lighter socket is technically called a Cigar lighter receptacle, since it was originally designed as a lighter for cigars—hence its rather large size (and unheated center barely large enough to light a cigarette).
These sockets were not originally designed to provide DC power, and are not an ideal DC connector for several reasons, notably the fact that three sizes exist (one for 6 V DC and two for 12 V DC) and the mating of the different sized 12 V DC plugs and jacks is problematic. Because of this, and the small gauge wiring sometimes used, they can sometimes provide only unreliable and current-limited power connections.
The polarity for 12V DC sockets is center pin positive (+), outer collar negative (-). Reversed polarity will damage some electronic devices.
[edit] Powerlet Connector
Similar in concept to an automotive cigar lighter, the Powerlet is shorter and smaller, and found most frequently on motorcycles (most frequently BMW cycles).
At least one manufacturer sells a plug that combines a cigar lighter plug and a powerlet, in much the same way that combination auto/airplane notebook computer power adapters combine a cigar lighter plug and an Airinc 628/Empower plug. The manufacturer that appears to have the widest selection of Powerlet plugs, sockets, and adapters is Powerlet Products. (They may also be the original OEM designer.)
[edit] Airline In-Seat Power Supply System
Two different airline in-seat power supply system (ISPSS) standards for DC power have been used in the past.
American Airlines has in the past used an automotive cigar lighter socket, but using 14.7 V instead of the automotive 12 V.
Most other airlines to provide DC power implemented the EmPower (ARINC 628, Part 2 specification) system, which uses a 4-pin Hypertronics' D-series connector that smaller in diameter and overall size than a cigar ligher plug.
[edit] XLR Connectors used for power
In the broadcast, film, and television industries, the 4 pin XLR connector is the standard for 12v power. The connectors are wired pin 1 negative, pin 4 positive. Often pins 1 and 2, will be negative with 3 and 4 as positive for a higher current rating. Female connectors are used as supply and male connectors are used on loads. Most battery belts and power supplies output 13.2v, but equipment can usually handle a range of 11-18 volts to accommodate battery packs of varying voltages and charging while operating.
The readily available XLR3 is also used by some manufacturers as power supply plugs despite their being a well-accepted standard for other purposes.
[edit] Other DC connectors
See also power connector.
- Binding posts and Banana connectors are quite commonly used as a power output on industrial and scientific DC power supplies.
- Fly RC magazine: Connectors Connection describes most or all of the connectors used by RC users.
- dcpowerjacks.net lists a number of connectors not yet included on this page.
- There are a number of similar design PC board power connectors, including Molex Mini-Fit SR, Molex Mini-fit jr., MOLEX MICROFIT and Molex SABRE connectors, and AMP DUAC connectors that look similar to each other.
- Miniature and subminiature jack plugs and even phono plugs are used instead of DC plugs on some equipment, especially in the lower price brackets. Jack plugs typically short circuit while being plugged in.
- Five-pin DIN plugs were used on many early personal computer power supplies. DIN and Mini-DIN plugs of various pin numbers also continue to be used by some manufacturers for power supply purposes.
- Some plugs with three, four, five or more pins are also called DC plugs. These were common on vacuum tube equipment and continue to be used where several voltages are supplied. On vacuum tube equipment the pins are normally on the equipment side of the join for safety reasons.
- Some data bus systems like USB or Firewire are designed to provide a limited amount of DC power to external devices.
- Many cell phones use DC connectors that are unique to the manufacturer. SHENGYIH makes connectors that fit about two dozen brands of cell phones.
- Winchester Electronics has an interesting snap-on power connector that might be appropriate for this page. [5]
- Apple Computer introduced the MagSafe DC power connector on the MacBook Pro line of laptop computers.
- Plastics One offers custom cable and connector manufacturing, primarially targeted at the medical and communications industries. If you find a DC connector not detailed elsewhere, there's a chance they made it. [6]
- ODU makes specialized industrial-grade connectors. [7]
- Article on battery-pack connectors. [8]
[edit] Summary
Modern equipment is often less sensitive to power supply mismatches than older equipment. However, the only safe courses are to use the manufacturer's recommended power supply, or to determine and match the voltage, polarity, current and filtering required. The fact that the plug does or does not fit the equipment is meaningless unless the equipment and power supply are from the same manufacturer, and unreliable in any case.
[edit] References
- Anderson Powerpole SB Connector Family data sheet
- GlobTek, Inc. has a data page that could be used to further research these and other connectors.
- laptopjacks.com has a list of laptop DC inlet jacks, by brand, that should be parsed for additional connectors for this page.
- Alden Products makes the Pulse-Lok line of connectors. Some of these may be used for DC.
- CUI, Inc. Connectors Most items include a color photo, and both 2D and 3D CAD data.
- Singatron DC Power Jacks Has PDF drawings for each part.
- Kycon Click on DC Power Connectors. Form-based link to PDF specifications don't work outside of frameset.
- Schurter Audio, DC, DIN Connectors
- Lumberg Series 47 Wiring solutions for photovolatic power systems
- Lumberg Series 16 Power supply connectors
- Philmore-Datak catalog page 63
