5V power in 90q??

[Ameer Antar]

First you should figure out what the power requirements of the laptop are. 
They're usually around 15-19V, not 5V [which would make things easier]. The 
rating will be on the wall transformer for the laptop, ie. 19V at 2.0 amps. 
The car voltage is 12V and has to be stepped up from this 12V D.C. to 19VDC 
or whatever. You can do this by using an dc-ac inverter and the wall 
trnasformer, or just a dc-dc regulator. The The first method converts 12VDC 
to 120VAC and then converts back to the laptop voltage...ie. 19VDC. The 
dc-ac inverter needs to handle more power than the laptop requirements, b/c 
going back and forth from dc-ac is inefficient. So if the laptop needs 56W 
or whatever, the inverter needs to handle a bit more. Also the ac output 
and waveshape from the inverters aren't the best for computers. But this 
the cheapest and quickest way to get power.

You can also get a dc-dc converter which goes directly from 12VDC to 19VDC 
or whatever. This is the most efficient way, but can be expensive, unless 
you build it yourself. The output is also very clean. Hope this helps.

-ameer


At 09:59 PM 2/25/2001 , you wrote:
>Okay...after reading the responses it sounds like the power inverter is 
>the way
>to go.  Just spend some bucks and save some trouble I suppose.
>
>How many watts to I need to run a laptop?
>
>will 140W do?
>
>-Dave
>
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