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[on:]

Hey what would you guys see as the smallest 120-240v to either 5v or 3.3v power supply? Probably atleast 100ma, and do you think this is something best bought or made? Also keeping it efficient and heat low is important so aswitching supply is definetly the route I know already

[Reply #1 on:]

Some mains USB chargers are pretty small, barely larger than a mains plug.

[Reply #2 on:]

what would you guys see as the smallest 120-240v to either 5v or 3.3v power supply?

Have you been to your local Apple store? They have all sorts of small USB power supplies that can be easily repurposed to an arduino.

[Reply #3 on:]

Here is an example: http://store.apple.com/us/product/MD810LL/A/apple-5w-usb-power-adapter?fnode=74

[Reply #4 on:]

I have one just like that for my Blackberry so it should be available everywhere else.

[Reply #5 on:]

Here is an example: http://store.apple.com/us/product/MD810LL/A/apple-5w-usb-power-adapter?fnode=74

I just upgraded my cell phone to a Samsung Galaxy S-II, and the phone came with a similar charger, that at 5v and 2a provides more juice than the normal USB wall warts I've had in the past (usually 0.5a).  I like this wall wart because it takes no extra space in a normal power strip.  Also, I was looking to bring up my Raspberry Pi, and I needed at least 1a for that.  I did some looking on ebay, and found some similar power supplies:

• From china, $3.99 + $0.99 s/h: http://www.ebay.com/itm/350610125612?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649
• From USA, $5.99 + free shipping: http://www.ebay.com/itm/160893728603?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649

[Reply #6 on:]

Just look for a usb charger on amazon on eBay, Yes Apple do do them like stated above but you pay 10x as much because it has a nice apple on the top! I bought one the same quality as Apples for a couple of quid of eBay! Happy buying!

[Reply #7 on:]

No, you probably didn't.  ;-)  There was a site posted around here recently where an EE dissected switching PSUs from Apple, some other phone co.s, and some cheap knock-offs.  There are appreciable differences in the design and component selection regarding things like filtering caps, space between HV and LV sections, transformer isolation and current capacity, and other things that dictate quality of output, and more importantly, user and property safety.  Don't skimp.  You don't have to pay the Apple tax necessarily, but at least get one with full regulatory certifications.  Although the Apple ones were of particularly high quality, so it may be worth it.

I consider this doubly necessary when the PSU isn't driving a well-engineered and tested load.

Be safe guys - PSUs are no joke.

[Reply #8 on:]

With all electronic accessories we have lying around, you can certainly find lots of power supplies: laptop adapters, phone chargers, battery chargers, ipad/iphone/ipod/... chargers. Any one of them would have worked for your mcu as a power supply.

Why pay if you get them for free?

[Reply #9 on:]

Im more thinking about total size, smallest coolest simplest the best, I've actually reused one of those before and it wasn't too expensive nd works well for what I needed it for, perhaps that is the way to go
for experiences sake tho, how hard would it be to mke something like tht from scratch or even to borrow the design and put it on my own board?

[Reply #10 on:]

Have you seen these AC/DC modules?
There are others in the same line with more output current too.
http://www.mouser.com/ProductDetail/RECOM-Power/RAC01-05SC/?qs=sGAEpiMZZMuEhFEw3BeJbWBvA%252bw%2fvMYdKI7FscCidR4%3d

[Reply #11 on:]

http://www.ebay.com.au/itm/New-20-50W-AC-220V-12V-LED-Power-Supply-Driver-Electronic-Transformer-bae-/221059782295?pt=AU_B_I_Electrical_Test_Equipment&hash=item3378309697

    Input Voltage: AC 220V 50/60HZ
    Output Voltage: AC 12V
    Output power: 20-50W Max
    Ta: 50°C Tc: 70°C
    Dimension: approx. 52 x 27 x 22 mm(L x W x H)
    Input and Output Cable length: approx. 10 cm


Package Included:
1 x Electronic Transformer

[Reply #12 on:]

12v is a lot more managable, I think the regulator of a standard arduino accepts up to 17v's so a 12v supply would be perfect as it would then supply you both
your 3v 5v rails and 5v logic pins.. but, you also have a high power source 12v with a high current you can use the lower 3-5v to switch on and off with power mosfets
and Power Transistors.

[edit] just noticed it's an AC out, even better, use 2 diodes to rectifiy the signal to dc, and you'll have something more like 9-10volts DC out, almost perfect voltage for a typical
arduino board (2 diodes, 20cents each..)

Any voltage you need, just buy a regulator for that voltage?...

Or am i missing it?

[Reply #13 on:]

$.99 including shipping.

http://www.ebay.com/itm/USB-Adapter-Adaptor-Wall-Charger-For-iPhone-3G-4-4G-iPod-Touch-nano-Colors-NEW-/271042037188?pt=LH_DefaultDomain_0&var=&hash=item3f1b5d45c4

[Reply #14 on:]

Zoomkat, fair enough and how many Watt rating is that?

5v * 1amp = 5watt power supply
vs
20-50W Max (so i'll reflect the min/max)
10-11v (after rectifier DC output and cap)

20W/11.5v = 1.73amps
50W/11.5 =  4.34 amps

20W/(11.5v > Regulator > 7V) (Recommended regulator voltage , which drops it down to 3/5v for the board) = 2.8amps
50W/(11.5v > Regulator > 5V) (not so good, as it stresses the regulator out) = 10 amps

?? 10 amps?  am i doing this right..

20w/7v = 2.8?
50w/5v = 10amps.

sounds kinda right, but that's a lot of power for AU $2.19 (Free postage)