It is an inverter device, its working principle is similar to switching power supply. Of course, you can also imagine a transformer device. According to scientific theory, it works by controlling a shock through a oscillating chip or a specific circuit. Signal output, such as output 50HZ signal, and then this signal is amplified to push the MOS tube [field effect transistor or crystal thyristor] to continuously switch, so that after the DC input, after the switching action of the MOS tube, a certain AC characteristic is formed. Correcting the circuit correction, you can get the sine wave AC similar to that on the power grid, and then send it to a transformer. This transformer is a power frequency transformer. It is a 220V to 24V transformer. If the input 220V, the output is 24V, and the input 24V, the output is 220V, it is actually a general 24V transformer. Then the transformer output, after output, is sent to the voltage regulator circuit protection circuit for use by the load.