Smallest power supply unit

Hi

I am looking for the smallest AC to DC power supply (in size) which i can use for arduino (input is 230v). I want it for light controling project.

I thought using small USB power device (e.g. Iphone usb charger) but i am not sure about it.

I will appriciate any help here.

Thx

This thread should answer your questions: http://arduino.cc/forum/index.php/topic,125697.0.html.

Thx,

Actually I saw this post after I have posted my ...

The problem is that there is no clear answer. I don't want to buy expensive USB charger and from what I read, the cheap one are not safe (I have one and now I am afraid to use it).

I think it will be great if there will be a solution around 2$ - 3$ which is safe to use.

the cheap one are not safe (I have one and now I am afraid to use it).

That's all based on posts on the internet by some random people?

Wow!

How about 3 AA batteries in a battery holder then? Get away from the high voltage mains altogether. Arduino can control transistors to control your lights, does not need much power for that.

I generally just use a wall adapter like this http://www.dipmicro.com/store/DCA-04510 and put a barrel plug, or screw terminals, on my board it to.

Couple of examples of wall adapter powered boards: '328 based board '1284 based board

eyco: The problem is that there is no clear answer. I don't want to buy expensive USB charger and from what I read, the cheap one are not safe (I have one and now I am afraid to use it).

If it has all the right symbols on it then it's passed safety certification. Look for the FCC approval mark (or whatever).

http://en.wikipedia.org/wiki/FCC_Declaration_of_Conformity

Couple of examples of wall adapter powered boards:

Nice.

I also use a lot of left-over power adapters from electronic devices that have seen their better days. Couldn't have been happier.

eyco: The problem is that there is no clear answer. I don't want to buy expensive USB charger and from what I read, the cheap one are not safe (I have one and now I am afraid to use it). I think it will be great if there will be a solution around 2$ - 3$ which is safe to use.

I think it would be great if I hit the $100M powerball lottery! :)

I thought of using batteries but I want to place all parts in the light switch box so replacing batteries will not be convenient. This is why I thought using the USB charger or other small power supply.

If it has all the right symbols on it then it's passed safety certification.

Cause no one in a third world nation would EVER dream of putting such markings on a device that hadn't actually passed safety inspections!

If you bought the supply from a reputable in-nation dealer (like amazon themselves) it's probably OK. If you bought it from one of the dealers that have sprung up importing things direction from China (and etc), the low prices that you get by bypassing customs probably means that you bypassed real certifications as well. It might be OK, and it might not. Measure it, look at it, make your own judgements.