How Power Supply Works?

Fig: How Power Supply works.

How to design a DC Power supply?
The first step of Power supply Design is Stepping Down the AC current into a lower voltage.
This is done by a Step Down Transformer.
Now we need to remove the Alternating Waves and make a DC Current from it.
For this purpose we will use a Bridge rectifier, in which the AC will be converted into DC.
Even if it is rectified, there will be some fluctuations in the output.
This can be removed by connecting a Capacitor Parallel, as it will not pass the DC and pass only the AC Current.
Thus the AC current will be bypassed through the Capacitor to the Ground and we will obtain a Direct Current signal at the output.
Now you can use this DC current for various applications.

In the image, the moving arrows shows that they are AC and constant arrows shows the DC.