Editing AC adapter (section)

==Advantages==
{{unreferenced section|date=December 2018}}
External AC adapters are widely used to power small or portable electronic devices. The advantages include:

* Safety – External power adapters can free product designers from worrying about some safety issues. Much of this style of equipment uses only voltages low enough not to be a [[safety hazard]] internally, although the power supply must out of necessity use dangerous mains voltage. If an external power supply is used (usually via a [[coaxial power connector|power connector, often of coaxial type]]), the equipment need not be designed with concern for hazardous voltages inside the enclosure. This is particularly relevant for equipment with lightweight cases which may break and expose internal electrical parts.
* Heat reduction – Heat reduces reliability and longevity of electronic components, and can cause sensitive circuits to become inaccurate or malfunction. A separate power supply removes a source of heat from the apparatus.
* Electrical noise reduction – Because radiated electrical noise falls off with the square of the distance, it is to the manufacturer's advantage to convert potentially noisy AC line power or automotive power to "clean", filtered DC in an external adapter, at a safe distance from noise-sensitive circuitry.
* Weight and size reduction – Removing power components and the mains connection plug from equipment powered by rechargeable batteries reduces the weight and size which must be carried.
* Ease of replacement – Power supplies are more prone to failure than other circuitry due to their exposure to power spikes and their internal generation of [[waste heat]]. External power supplies can be replaced quickly by a user without the need to have the powered device repaired.
[[File:Steckernetzteil mit Adaptern IMGP2309 smial wp.jpg|thumb|AC adapter supporting four different AC plug systems]]
* Configuration versatility – Externally powered electronic products can be used with different power sources as needed (e.g. 120 VAC, 240 VAC, 12 VDC, or external battery pack), for convenient use in the field, or when traveling.
* Simplified product inventory, distribution, and certification – An electronic product that is sold and used internationally must be powered from a wide range of power sources, and must meet product safety regulations in many jurisdictions, usually requiring expensive certification by national or regional [[Safety standards|safety agencies]] such as [[Underwriters Laboratories|Underwriters Laboratories (UL)]] or [[Technischer Überwachungsverein|TÜV]]. A single version of a device may be used in many markets, with the different power requirements met by different external power supplies, so that only one version of the device need be manufactured, stocked, and tested. If the design of the device is modified over time (a frequent occurrence), the power supply design itself need not be retested (and vice versa).
*Constant voltage is produced by a specific type of adapter used for [[computers]] and [[laptops]]. These types of adapters are commonly known as eliminators.