On 11/25/2014 09:54 AM, John Andersen wrote:
On 11/25/2014 9:51 AM, Anton Aylward wrote:
On 11/25/2014 12:48 PM, John Andersen wrote:
Everything inside your computer (beyond the power supply) runs on DC.
With a DC supply, capable of generating 5 and 12 volts, you don't need anything else.
You can power a 19 volt laptop from 2 car batteries for many days on end. All you need is a LM7809, which will set you back $1.95 plus shipping. Which begs the question ... If everything runs on 5V (the electronics) and 12V (motors, burners), then why is 19V needed?
Actually, virtually everything in a laptop runs on 5 volts or less. Even the disk drive and fan motors. 12 volts is pretty much absent inside a laptop.
I don't know why they choose to standardize around 19 volts, but I suspect it has something to do with the voltages needed for the screen.
The laptop will have small DC-to-DC converters and/or regulators to develop the needed voltages. With 19-VDC from the wall-wart they've got plenty of "headroom" to run their regulators. Note that there are other voltages running around in there to power the CPU, which uses something around 2.2-VDC I think. Regards, Lew -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org