My tablet needs 5v, 2A to charge via the micro usb but all I have is a
700ma walwart (which does not work) so I was thinking I could use my ATX power supply. There are 2 rails on the ATX for 5v, one for 30a and one for 2a. Is there any reason I cannot use either rail? The tablet will only draw the current it needs, right?
Yes, your supply can have infinite current and as long as the load only draws 2 amps then the supply just happily idles along.
Now, some switching supplies require a minimum load to boot, but most of the ATXs will power up (even with a tiny load) if you short the correct control lines.
John :-#)#
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Don't do it!!! There are several reasons that this is risky. And none of them have anything to do with the numbers printed on the labels. Yes, you'll find 100 people who say it's ok. And maybe 10 who say they've done it successfully. But not likely any who used your exact supply on your exact tablet.
99% probability that it will work fine is of little solace if you're the 1%. If you knew what you were doing, you wouldn't be here asking. Bottom line: Get a supply designed for this kind of application.
Is it worth the risk of damaging the tablet? Micro USB has 2 wires that determines the charger capabilities. If they're not present or used, a 5V supply is only allowed to operate the device, not charge the battery. Chances are good that your creative wiring isn't going to work.
Since you didn't bother to mention the Thinkpad tablet model, I can't offer a specific supplier. There should also be plenty of iPad 2 and Kindle chargers, which also require 5v 2A power. Count the number of pins are there are different flavors of microUSB.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
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