I'm working on a few projects to control line voltage, and wonder about a simple way to get a DC source for a stripped-down Arduino circuit without using a wall wart.
It seems strange to me that 5V USB sources are small, inexpensive and easy to find, but I can't find their guts anywhere, nor can I find the guts of a wall wart without the black plastic and prongs.
You need the high power AC line to be entering the box of your project and have the AC/DC converter on the same board as the low power DC circuity, instead of having the $3 1A wall wart close to the wall and only 5V DC entering your box?
This one is very easy to be opened: http://www.dealextreme.com/details.dx/sku.29417
and used.
Some details about using one in a project can be found in this article: http://spritesmods.com/?art=rgbledlamp
Osgeld, those are nice, current-wise; still bigger than wall warts but it looks like I was looking for the right thing!
RC, I don't need much more than 100mA-- just a few LEDs and a small relay-- so the Rohm should work, but like you said, it's not isolated-- I didn't like that example circuit from the datasheet! MPJA sounds interesting-- good link.
mircho, I think that sort of little supply might be the best route; would prefer something with standoff mounts and terminals, but it seems like those quadruple the price...
Wall warts are safer and probably cheaper. Mass produced, you know. And frequently small enough to fit inside a project box. Depending on how many you need, you may be able to extract the guts of a cellphone or USB-style wart. Frequently they see, to be nicely modular:
I would avoid bringing un-isolated high voltage AC into your
project enclosure. If you could find a chassis mount version
of a desktop supply like this one --
then the AC would confined to the sealed module. You would have a removable cord
and a safe isolated DC voltage.
Although the wall-warts are ugly they are a safe and convenient.
westfw, I'm using a very similar Motorola USB charger's guts in my current timer project, with added screw terminals, and I'll zip-tie it to a piece of acrylic and mount in the case with standoffs.
jluciani, agreed-- AC in the enclosure should be avoided, but the circuits in question are all about controlling an AC load, so it's already in there. I'm being careful with wiring and mounting, using a fuse far below the ratings of my relay and wiring; I used to mess around with neon lighting years ago (7.5-15kV), so am probably more cautious than I need to be
