On 10/2/06, John H. Robinson, IV <[EMAIL PROTECTED]> wrote:
kelsey hudson wrote:
>
> But yes, generally matching the specs exactly is the way to go. :)
You can safely use a powersupply that has a *greater* wattage or power
than the device requires.
Using a powersupply that is underratted in amperage or wattage is a good
way to start a fire.
Voltage must be matched. Polarity must be matched. Type of power (AC or
DC) must be matched.
Note that internal to the laptop computer there is a switch-mode DC to
DC converter that produces the voltage that the system actually uses
internally. (something like 5.0V). The input voltage used by the
converter can vary over quite a wide range. But this is probably not
documented on a label stuck to the outside of the box.
One-point example. My Thinkpad 600E. The output of the battery pack
is nominally 10.8V. The battery charger/power supply is rated at 16V
3.3A. Its open-circuit voltage is 16.33 at this moment. For those
Electrical Engineers reading, I don't intend to measure the
short-circuit current.
Some laptops must be made to tolerate at least a 50% variation in
input voltage, since they can run from either 6-cell or 9-cell battery
packs.
carl
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carl lowenstein marine physical lab u.c. san diego
[EMAIL PROTECTED]
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