The function of power adapter is transformer and rectifier. Household AC is 220V, while our computer land is 12V DC (as if), so we can be sure that the power adapter is a transformer and rectifier. Then the adapter is a transformer. We should all know that AC 220V is transformed into voltage through the transformer and DC through the rectifier. There is consumption here, and these consumption will be transformed into heat, so it is normal for the power adapter to heat. The transformer is made of silicon steel sheet. After the transformer is powered on, magnetic flux will be generated, which will lead to the force action between silicon steel sheets, resulting in buzzing sound, which is normal. However, the earth sound is abnormal due to many reasons: 1. The AC voltage is unstable. 2. The chip is broken. 3. Turn to turn short circuit. 4. The element is damaged.
Characteristics of power adapter
The power converter (i.e. AC to DC) converts from AC to DC, and then passes through the computer. It can not protect the computer, but there is a memory (also known as charger) for storing power in the computer, so it can protect the computer in case of power failure. Both switching power supply and adapter are switching power supply, which are composed of high-frequency switching tube and its control circuit. The adapter power supply is a regulated switching power supply. The switching power supply charger has a floating charge function. The voltage increases with the decrease of the current. In the end, there is only voltage but no current.
