Power adapter is a power supply conversion device for small portable electronic equipment and electronic appliances. It is generally composed of shells, transformers, inductors, capacitors, control ICs, PCB boards and other components. Its working principle is to convert AC input to DC Output; According to the connection method, it can be divided into wall type and desktop type. Widely used in security cameras, set-top boxes, routers, light bars, massagers and other equipment. There are generally several items that need attention on the label of the power adapter (hereinafter referred to as the adapter). First, it is the model of the adapter. For example, the model of this adapter is XVE-120100. It tells us a few pieces of information, including its manufacturer, main parameters, etc. The name of XVE is generally ##company code, and 120100 means this. The adapter is 12V1A, the 050200 is 5V2A; the second is the INPUT (input) of the adapter, which is generally AC100-240V~50-60Hz in China, which means that the adapter can work normally under the AC voltage of 100V-240V ; The third is the adapter's OUTPUT (output), DC 12V=1A, which represents a DC voltage with a rated voltage of 12V and a maximum current of 1A. Two numbers can quickly calculate the wattage of the adapter. For example, in this adapter, the voltage is 12V*current 1A=12W (power), indicating that the power supply is a 12W adapter. Most notebook computer power adapters can be used for 100 ~ 240V AC (50/4878Hz). Basically, most laptops have an external power supply and use a power cord to connect with the host, which can reduce the size and weight of the host. Only a few models have the power supply built into the host.