Raspberry PI Power

[Scott Allen]

On 2 August 2013 13:39, William Weaver <williamdweaver-Re5JQEeQqe8AvxtiuMwx3w at public.gmane.org> wrote:
> I totally agree that it's easier to measure the Voltage than the current,
> the problem is for the situation the RPi is going to keep the voltage
> constant on the 5V rail.

No. The RPi requires a regulated 5V input. It's up to the power supply
to keep the voltage constant at 5V regardless of the current draw. If
the RPi and whatever else is being powered requires more current than
the supply can provide, then either the voltage will drop or the power
supply will blow a fuse, shut down, or burn out, depending on the
supply's design.

Thus, measuring the voltage under full load is a valid way of
determining if the supply can provide adequate current. Note, though,
that using a meter to do this won't show any ripple. It's possible
that under high load the ripple voltage on the supply will be out of
tolerance and cause problems. You would need an oscilloscope to show
this, but the same goes for current measurements.

-- 
Scott
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