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The problem is: I've got a power supply capable of outputting 19.5V 4A. I need to lower the voltage to power up a laptop that requires 15V and 2A. Which way is the best to do it? Construct a voltage divider from some resistors? Use a LM317?(datasheet says it can output "in excess of 1.5A" - what does it mean? That it will tolerate 2A?)

user905747
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  • This doesn't answer your question but it might help you with some background knowledge about power supplies: http://electronics.stackexchange.com/questions/34745/choosing-power-supply-how-to-get-the-voltage-and-current-ratings And this one on the idea of using a voltage divider: http://electronics.stackexchange.com/a/111647/6334 – The Photon Jun 29 '15 at 19:16

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Use a buck regulator is realistically the sane choice. Maybe one of these: -

enter image description here

They appear to cost about £7 from ebay here.

But, as always read the small print and check out a few others. I just googled "15V 3A buck regulator" and this was the first hit and I think it may be a little underpowered so go for something a tad beefier.

Andy aka
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