AC adapter

A linear or switched-mode power supply (or in some cases just a transformer) that is built into the top of a plug is known as a "wall wart", "power brick", "plug pack", "plug-in adapter", "adapter block", "domestic mains adapter" or just "power adapter". They are even more diverse than their names; often with either the same kind of DC plug offering different voltage or polarity, or a different plug offering the same voltage. "Universal" adapters attempt to replace missing or damaged ones, using multiple plugs and selectors for different voltages and polarities. Replacement power supplies must match the voltage of, and supply at least as much current as, the original power supply.

The least expensive AC units consist solely of a small transformer, while DC adapters include a few additional diodes. Whether or not a load is connected to the power adapter, the transformer has a magnetic field continuously present and normally cannot be completely turned off unless unplugged.

Because they consume standby power, they are sometimes known as "electricity vampires" and may be plugged into a power strip to allow turning them off. Expensive switched-mode power supplies can cut off leaky electrolyte-capacitors, use powerless MOSFETs, and reduce their working frequency to get a gulp of energy once in a while to power for example a clock, which would otherwise need a battery.

This type of power supply is popular among manufacturers of low cost electrical items because

1. Devices sold in the global marketplace don't need to be individually configured for 120 volt or 230 volt operation, just sold with the appropriate AC adapter.
2. The device itself doesn't need to be tested for compliance with electrical safety regulations. Only the adapter needs to be tested.

Other advantages of using separate power adapters are: removing the transformer as a source of heat, separating mains voltage, and making the devices smaller

Click on the picture below for more information:

	Koolatron Multi-Purpose Adapter 110AC to 12 Volts DC ( Model AC-15) Average Rating:
	Koolatron specializes in portable 12-volt devices, such as coolers, freezers, or microwaves, that plug into a car's cigarette lighter or other 12-volt source. With the Koolatron 110-volt adapter, you can use these same devices wherever you have access to a 110-volt outlet...

	Power Line 0900-56 12-Volt DC-AC/1000 mA Power Socket with Enhanced Digital Power Average Rating:
	DC-AC Power Socket

	Power Line 0900-27 Global Power Travel Kit Average Rating:
	Global Power Travel Kit

	Franzus TSM-1875CK International 1875 Watt Converter/Adapter Set Average Rating:
	1875W Converter With 5 Plugs

	Franzus TS-185TR Heavy Duty Tranformer Average Rating:
	The TS-185TR converts 220V electricity to 110V for continuous use on electronic products (VCRs, computers, fax machines, etc.)PRODUCT FEATURES:0-85 watts;Built-in 3 prong grounded receptacle;European grounded Schuko plug and power light.

	Conair-Pro International "4" Plug Adaptors-Worldwide Usage #Cp950
	Set of five polarized adapter plugs. These plugs adapt to most outlets found worldwide. For international use with dual voltage appliances ONLY.

	Adapter for Connecting 230V Electrical Device with North American Plug to EU ...
	This pin adapter allows you to plug electrical devices with North America plugs in to EU (Europe) style outlets, making it great for travel purposes! However, this is a pin converter only and does not convert voltage, so proper care should be taken to verify your device is capable of running on this higher voltage to prevent damage...

	Adapter for Connecting 230V Electrical Device with North American Plug to UK ...
	This pin adapter allows you to plug electrical devices with North America plugs in to UK (United Kingdom) style outlets, making it great for travel purposes! However, this is a pin converter only and does not convert voltage, so proper care should be taken to verify your device is capable of running on this higher voltage to prevent damage...