need advice for 12V 2.5A switching power supply

[T3STY]

need adive for 12V 2.5A switching power supply

I understand the basic work that a switching power supply does, but I am a total noob in this field and I am unable to build one from scratch and I'm not even able to evaluate if any scheme found on Google is OK or not.
I'm looking for a switching power supply to power 108 series of LEDs at 12V (3 leds + 150Ohm resistor per series). The amount of LEDs series will use around 2.2A (20mA per series - LEDs rated 3.2V 30mA max). I will use the same 12V power supply to get a 5V power supply to a PIC16F876 (I'll use a 5V voltage regulator like 7805).
I have specified 2.5A because that would be the very maximum current I could possibly use if I'll make any modifications to the project or if I miscalculated the current consumption (I hope I didn't).

This question is not actually a "is this ok" question, but a real "could you do it for me" request. So if someone has the knowledge to design a 12V 2.5A switching power supply for me I'd be very very grateful. If you think is not in the spirit of this forum helping like this, I will understand and I won't blame you.

I know it's not much but when the project will be over I'll publish it on the forum with all the sources and designs, hoping it will be better than a simple thank you.

Thank you in advance.

 

[tpetar]

12V 5A switched power supply
http://danyk.cz/impulz3_en.html

:wink:

 

[T3STY]

It looks nice, but as far as I understood it requires as self made transformer. I don't think I am able to build it.
Is there any other solution using a commercial available transformer?

 

[tpetar]

This trafo is easy to made.

Extract trafo from some bad PC psu.

 

[T3STY]

I've got an old 80W PC power supply, I guess I can reuse the components from there. I'll try, let see if it works.

 

[deepakchikane]

u can design it with pi softwares... by using tny 278 ic...check application note

 

[tpetar]

Yes TinySwitch ICs are good.

 

[T3STY]

In these days I've been trying out a few circuits and I could successfully build a good power supply using tny278 (the others failed to work, as expected). But the circuit still uses a transformer at the beginning, and in this project I haven't got enough space to fit it in. This is why I've decided to use an external power supply. There are laptop power supplies that can carry out up to 19V 4A, but even the lowest ones carry out 16V 3A, so they're powerful enough. This is the best choice for now, in future I'll work harder on those switching power supplies.

Thank you for any help guys