next topic »

[Reply #15 on:]

I thought the need was for 100mA? 0.5W total?

[Reply #16 on:]

Why settle for a ford mondeo when for an extra few bucks you could buy a ford GT ..

is it not better to "have" than have not?

[Reply #17 on:]

Careful, there are a lot of dodgy USB "chargers" out there these days.  Typically they'll have poor regulation that might be ok for most phone's charging circuits, but not so good for powering ics directly.

[Reply #18 on:]

how hard would it be to mke something like tht from scratch

The answer would depend on how complicated "that" is.

In the simplest form, it can be a rc network. In a more reasonablly engineered form, it could contain an isolated switching mode power supply, with good common mode filtering and power factor correction, and low idle power -> you may find a mcu far more powerful than you arduino reside in one of them.

The cheapos you get off ebay probably are a lot closer to the dangerously simple types.

[Reply #19 on:]

http://www.electronicspecifier.com/AC-and-DC/VSK-S1-VSK-S2-CUI-AC-DC-Encapsulated-Power-Modules-2-Watts-08-in3-space-saving-package.asp

[Reply #20 on:]

That's comparable to the Recom part I linked to from Mouser.
http://www.digikey.com/product-detail/en/VSK-S1-5U/102-2595-ND/3465373
5V, 200mA unit is a few dollars cheaper.

[Reply #21 on:]

Here is the teardown comparison

http://hackaday.com/2012/05/20/iphone-charger-teardown-shows-astounding-miniaturization/

[Reply #22 on:]

Here is the teardown comparison

Is he sure that he was tearing a real Apple charger? The "genuine" one he took apart looked to me of lower quality than the "fake" ones he linked on the sme page.

[Reply #23 on:]

Why settle for a ford mondeo when for an extra few bucks you could buy a ford GT ..

is it not better to "have" than have not?

The origional request seems to read "Probably atleast 100ma". For only $1 shipped it would be worth a try. Bigger and more expensive may not be better. Why buy a ford GT when all the kids won't fit in when going to the store?

[Reply #24 on:]

http://www.eevblog.com/forum/general-chat/dodgy-usb-power-supplies/msg138465
http://www.eevblog.com/forum/product-reviews-photos-and-discussion/dlo-power-bug-usb-charger/msg147767

Recommended "cheaper than apple" tiny USB supplies seem to include the kindle charger ($10 http://www.amazon.com/Kindle-Power-Adapter-included-Paperwhite/dp/B005DOK8NW )
and the samsung charger ($6 http://www.amazon.com/gp/product/B005OSURT2/ )
Beware counterfeits!

It would be worthwhile to measure the output voltage of a suspect supply before connecting it to your expensive Arduino project...

For small quantities, check out a thrift store.  "Orphaned" power supplies (ie from cellphones) frequently seem to end up there, sold for very cheap. Most of these are approx 5V, these days.

[Reply #25 on:]

Here is the teardown comparison

http://hackaday.com/2012/05/20/iphone-charger-teardown-shows-astounding-miniaturization/

That's a nice article -- the one at Ken Shirriff's blog. I'm far from an Apple fanboi, but they do, in most cases, build very good hardware. I'm now curious what the guts of my LG charger look like. It sure isn't a $30 item.

[Reply #26 on:]

The requirement was definetly a minimum,  more the merrier, this is for a design for somethi that is going to be behind regular house outlets and switches(probably in the same box, so im trying to keep it cool and small as possible, basically going to be powering an attiny84/85, relays, leds, perhaps some other comm peripherals
so while quality isn't the most important,  reliability definetly is, something that could be expected to last perhaps atleast 3 years by itself in a closed enviroment, without gtting hot or posing a fire hazard lol

[Reply #27 on:]

The little recom units or the same at digikey would seem to be good for that.

[Reply #28 on:]

Hmm fter looking at it I kinda like that digikey item, have you used one before?

[Reply #29 on:]

No. I am using a Recom 24DC to 5VDC unit on a card. 24V drives motors, 5V drives the uC & logic.
I think boffin1 down in South Africa is using a mains to 5VDC module like I recommended.