You can use this power supply for your electronics project which only require electric current about 500mA. This is cheap circuit which will give you stabilized output voltage.
If you want to change the output voltage, you should change the IC type.
For example, you need 5V output, then change the IC from 7098 with 7805 dan [...]

This is a simple low-cost 12 Volt 50W off-line switching power supply, which can be used for home projects or to learn operation of flyback converters. It can work over a universal AC line input range 90-264 VAC and provides a 12VDC output at more then 4A load. Line and load regulation is better then [...]

The ac from the transformer secondary is rectified by a bridge rectifier D1 to D4 which may also be a block rectifier such as WO4 or even four individual diodes such as 1N4004 types. (see later re rectifier ratings).

The principal advantage of a bridge rectifier is you do not need a centre tap on [...]