Crude Pico PSU for ATX

[onoffman]

The pico PSU is favourite device for fan-less PC.

I have collected ebay data to see the volt and AMP needed to make One.

Now i grabbed a Buck circuit with flexi voltage conversion via zener selected .

This is Ckt-A

And for the little -12V line Ckt-b is selected

I am sure being a newbie there may be lot mistakes .
Doubts
A)I think we cant do 12V to 12V for that requirement
we can select input as 14V
and tweak other circuits to get the needed voltages
B) what will be the Ckt-b values for -ve 12v from 14V+
C)Will Ckt-b provide 0.5AMP ?
D) May not be super good design ,
Will it work ?





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Also better alternatives with simple components if possible

 

[onoffman]

No one , all are laughing at this ??

 

[BradtheRad]

It is not clear what you plan to do.

Do you wish to make your own Pico PSU?
Or do you plan to get one so you can derive more outputs from it?

It appears that you want to obtain a negative supply from a positive. A buckboost converter will give you that. (A buck type will not.) You can also use a charge pump topology.