How to design a switch mode power supply (SMPS) circuit with dual output voltages?

I want to design a switch mode power supply circuit with dual +/- 5V and +/- 12V outputs, i have no idea where to start with it. The whole feedback circuit part is confusing me, what components should be used there, how should they be wired, what exactly are they doing? Also i'm not sure what type of switch... show more I want to design a switch mode power supply circuit with dual +/- 5V and +/- 12V outputs, i have no idea where to start with it.

The whole feedback circuit part is confusing me, what components should be used there, how should they be wired, what exactly are they doing? Also i'm not sure what type of switch (transistor) should be used?

Any help with the design of this circuit would be great!
Update: Hi

It has no specific use with a maximum power of 20-50 VA.

Multiple output connectors is prefarable, ie 5v +/- 2connectors
and 12v +/- 2 connectors.

Thanks
5 answers 5