AC power adapter knowledge base:

Known by a variety of names from adapter brick to wall mount power supply, the ubiquitous small plastic boxes are the most common source for low voltage power.

Power adapter are available in a variety of performance, quality and price levels, and since price can often be the key deciding factor, it is important to understand the differences in power adapters when supplying power to your product, and how the differences affect the overall price.

Power adapters come in two basic varieties AC/AC and AC/DC:

AC/AC - AC/AC power adapters are simple step-down low voltage transformers, accepting AC input and providing a certain voltage AC output. There are no other active or passive components. With no line regulation at all, an AC/AC adapters output voltage is proportional to the input voltage. AC/AC do have a small amount of load regulation, with the transformer windings being a significant part of the load.