When active voltage stabilizing components are used inside the power supply, even if the mains voltage fluctuates, the output is constant. Like small transformers on the market, such as Walkman power supplies, if the mains voltage fluctuates, the output of the power supply will not fluctuate with it.

Generally speaking, the true no-load voltage of an ordinary power adapter may not necessarily be completely consistent with the nominal voltage, as the characteristics of electronic components cannot be completely consistent, so there is a certain error. The smaller the error, the higher the consistency requirements for electronic components, and the higher the production cost, so the price is also higher.