Build power supply

Hi everybody, I'm trying to build a power supply for arduino, but I'm too noob to reach this goal, so I need some help. My skills in eletronics is very basic I just study something in internet to realize some porject with arduino. I'm actually a programmer. Searching on the web I found this page What do you think? Is possibile make it for arduino? And is possible to find an equivalent transformer in RS ?

I hope this is not a stupid question XD.

Thanks to evrybody for the support given to me and the support that will give to me.

Buy a wallwart instead. 12V, 1A, output that is short circuit protected, all packaged up.

nontrovavounid: Searching on the web I found this page What do you think? Is possibile make it for arduino?

That might work, but I wouldn't feel safe sitting next to it.

(Where to begin...? No isolation, no mains-rated capacitors, exposed AC wires, no heatsinks or short-circuit protection ... it doesn't even have a fuse in it!)

You can get a 12V supply for about $5. It's simply not worth building your own if you're a beginner.

Trying to buy one from the store is a little too expensive? Well, you can make a 12 volt power supply very cheaply and easily!

IMHO, Power supply is one of the worst electronics projects to start with, as a noob.

You might be able to follow this instructable, but if you have to buy more than half of the parts, you will end up with an expensive solution. Don't buy heavy transformers. What do you want do do with a 12V supply ? Is there more than the Arduino itself to feed ?

Better find a whole wall wart in the electronics dump bin. Look for 5V devices, and if it really supplies less than 5.5V, attach its + wire to the 5V pin. If its above 6.5V, attach it to Vin.

Thanks to all for the tempestive reply, I want develop it because I need a smaller one to connet at another PCB, I can't use a wallwart is too cumbersome. I need something like this but with the right voltage (220 to 12v). I try to serach it on internet but I didn't get a good result. Anyone know where I can find it?

RECOM makes a series of AC/DC and DC/DC converters, carries them.
Here are examples for AC to DC converters.
You mount it on your PCB. You still need a mains cable, a fuse, and perhaps an output capacitor.

I would think a wallwart connected to a barrel jack connector or maybe screw terminals would be less bulky.
Arduino does not need 12V either. A 5V supply connected to the USB connector will do.
So something like this

Thanks roadcross, but is too expensive as solution. What do u think about this component ? Is 1W enough? And If I want use the first solution waht kind of transformer should I use?

CrossRoads: Buy a wallwart instead.

If you are anything like me, look through the junk box and just find one. Average households must have about 20 of these things going at any time these days with a bunch more in closets or, like me, in plastic storage bins. No reason to throw these away, keep them.

CrossRoads: RECOM makes a series of AC/DC and DC/DC converters, carries them.

I just don't get how they can sell those. It's a power supply that is more expensive than a lot of applications are completely assembled and packaged for retail. Maybe for lab instruments, but no consumer level goods maker could ever justify that cost.

Those were just examples - I am sure you can find other European solutions, the ones Amazon presents here tend to be universal units for travellers. I have a little cube that my wife found for $5-6 with US prongs. That little blue one is only 200mA, I was thinking you needed 1000mA for some reason. Are you looking for a 1-time prototype, a multi-unit solution, something you can make a lot of? If you've noticed, most electronics push the power supply out of the electronics unit. So I'd go for some approach whereby you bring in DC and use it straight up, or have a small linear regulator to knock the DC down a little more to your working voltage as the Arduino does.

Not sure what the market is for the RECOM AC/DC units. They have DC/DC that are much better priced.

Thanks Crossroad for the help that u are giving to me, and I'm sorry if my question wasn't so clear. I want to do a components that is possible connect directly to the wall supply, inside that component there will be:

The component have to be small as mach as I can do it.

So do u think that the small blue component that give 1W to Arduino is enough?

Thanks again

That's only 200mA maximum at 5V 1W. Is that enough for your circuitry? How are you driving the relay?

The circuit is this: and the realy is If the problem is just that there are not enough mA I can use this one so I will have 500 mA in 5V, I will put also a fuse 250V 5A. Do u think is a right solution?

200mA should drive the Arduino & that transistor/relay just fine.