[ale] Pi power source

[Boris Borisov]

Even if I threw away some electronics (printers, modems, VGA-TV
converters, old DSL modems and etc. ) I tend to keep the external
power supply. These have a good voltage output at the whole range of
current loads. Cheep electronics ( cheep speakers or exae) for example
have a supply which voltage output varies from 11 volts at no load
down to 5 V or less at full load. If you can measure I do some tests
first make sure the voltage is right.

On Sun, Nov 25, 2012 at 9:07 AM, Ron Frazier (ALE)
<atllinuxenthinfo at techstarship.com> wrote:
> I don't have a pi (yet), but I can speak in terms of general electronics.  It's fine (and even desirable) for the charger / power supply to have more current capacity than the load (the pi) needs.  The load will only use the current that it needs as you said in your question.  Just as your car may have a 200 HP engine and use only 20 HP to get it down a flat road, the load will draw more and more current as it's requirements go up depending on what it's doing and what's attached to it.  You need to account for the maximum specified current draw for the pi as well as anything that's attached to it and powered from it, such as a usb mouse and keyboard, etc.  The power supply should be able to handle the maximum load of all the connected devices that don't have their own power supply.
>
> You do want to make sure your power supply has an output VOLTAGE within the specified limits of the pi, not too high nor too low.  You also want to make sure the polarity of the voltage (+ wire, - wire) is correct.  If you're using a standard micro or mini usb plug on a factory made power supply, the polarity is controlled automatically by the way the connector is inserted into the slot.
>
> It is possible in the far out case that if you had a really huge power supply, say 200 amps, and were drawing only 1 amp, that the power supply would not properly regulate it's output and there could be problems.  However, that's not the situation that you described.
>
> Hope this helps.
>
> Sincerely,
>
> Ron
>
>
> Doug Hall <doughalldev at gmail.com> wrote:
>
>>Is a "standard" 1 amp (5V) phone charger going to overpower my
>>Raspberry
>>Pi? I've read where it requires at least a 700 milliamp power source,
>>but I
>>don't know what the maximum amperage can be. Is the device only going
>>to
>>draw what it needs?
>>
>>
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