Adding external HDD to Raspberry Pi

[Ori Idan]

On Tue, Dec 23, 2014 at 4:19 PM, Alex Shnitman <alexta69 at gmail.com> wrote:

> Power on the Raspberry Pi is a tricky business. I think on the B+ they've
> made it easier to deal with but it still cannot pass through a lot of
> current. So a powered hub is necessary, as previous posters mentioned.
>
> It does indeed backfeed into the Pi. I used thin stripes of electrical
> tape to cover the outer two contacts within the USB connector of the cable
> that connects the Pi to the hub, and that took care of that problem. Also,
> I found out that my hub (a cheap piece bought from DX), even when
> externally powered, would draw some current from the Pi during load. So the
> electrical tape took care of that too.
>

I find it strange that it actually work since if you isolated both the
power and the ground pins, the data pins are left floated. That might work
but cause noise problems. So if you do want to isolate, isolate only the
power pin.


> If you have a good power supply for the hub you can power your Pi from the
> hub itself with an additional cable (i.e. the hub will be connected to the
> Pi twice, once with a USB A-B cable like any hub, and once with a USB A -
> MicroUSB B, from one of the hub's ports into the Pi's power supply port).
> This removes the need for a second power supply.
>
> One problem that I faced, though, was that a wifi dongle connected to the
> hub was being disconnected and reconnected every few minutes. I plugged it
> directly into the Pi itself and it works flawlessly. I still don't know why
> that problem happened; after all, they both are on the same power supply
> (the hub's). Other devices on this hub (the Pi itself as well as other
> stuff) seem to work fine. Maybe the hub's power supply is noisy and the Pi
> filters it when it passes it through. No idea.
>
> Alex
>
>
Ori Idan
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