Hi.
If I supply RPi enough power (maybe a 2A PSU), can it run my USB hard drive (2.5" 5200rpm), which must be using something more than 500mA when active?
I want to power the Raspi + the hard drive + a tiny 5V fan (about 100mA) (no keyb or mouse, just ethernet and HDMI), 2A should be plenty, or not? Using a single USB port for the hard drive and connect the fan to a RPi's pin.
The fan is similar to this:
http://blog.aerco.co.uk/wp-content/uplo ... nt-fan.jpg
And will be running on 3.3V/5V pin, which will seem better (it just because it's cute, and the RPi will be running attached to a plasma TV (they run hot).
NOTE: I want to avoid a powered USB hub due to cost and bulk. Thanks
Re: Rapberry Pi Power
It is possible that it may work - if you are very lucky!
The PSU current isn't the limiting factor. The fuse F3 on the Pi is. The fuse is fine up to about 700mA, after which it starts to increase resistance and reduce the power getting to the Pi. If the current through the fuse gets above 1A/1000mA it will block so much that the Pi won't work.
You could supply power to the GPIO pins instead as this bypasses the fuse (be very careful!), or you could get/make a short USB extension lead with the red 5V wire disconnected from the Pi and connected to the PSU 5V line.
I'd also worry about electrical noise or spikes from the fan if run from the Pi - possibly put a capacitor and reverse-blocking diode across it's supply.
The PSU current isn't the limiting factor. The fuse F3 on the Pi is. The fuse is fine up to about 700mA, after which it starts to increase resistance and reduce the power getting to the Pi. If the current through the fuse gets above 1A/1000mA it will block so much that the Pi won't work.
You could supply power to the GPIO pins instead as this bypasses the fuse (be very careful!), or you could get/make a short USB extension lead with the red 5V wire disconnected from the Pi and connected to the PSU 5V line.
I'd also worry about electrical noise or spikes from the fan if run from the Pi - possibly put a capacitor and reverse-blocking diode across it's supply.
Re: Rapberry Pi Power
Many Thanks! I'll go with external power then. I have a couple of nokia 5V/1A chargers lying arround, I'll sacrifice onerpdom wrote:It is possible that it may work - if you are very lucky!
The PSU current isn't the limiting factor. The fuse F3 on the Pi is. The fuse is fine up to about 700mA, after which it starts to increase resistance and reduce the power getting to the Pi. If the current through the fuse gets above 1A/1000mA it will block so much that the Pi won't work.
You could supply power to the GPIO pins instead as this bypasses the fuse (be very careful!), or you could get/make a short USB extension lead with the red 5V wire disconnected from the Pi and connected to the PSU 5V line.
Injecting power that way (after the voltage regulator) doesn't seem a good practice to me. :\
Again, many thanks, I'm adding a veroboard for this.I'd also worry about electrical noise or spikes from the fan if run from the Pi - possibly put a capacitor and reverse-blocking diode across it's supply.
Re: Rapberry Pi Power
Personally I would bypass the whole thing and use a powered hub. If you connect the drive through the powered hub you won't have to worry about the Pi's USB power supply.
It does mean a second wall wart is needed to power the hub. I would suggest you find one of the hubs that provides a "charger" usb slot. This isn't a real USB port, just power. You would be able to power the pi, run the HDD off the same single wall socket. It would also give you head room for other power hungry devices, like wifi or 3g chips
It does mean a second wall wart is needed to power the hub. I would suggest you find one of the hubs that provides a "charger" usb slot. This isn't a real USB port, just power. You would be able to power the pi, run the HDD off the same single wall socket. It would also give you head room for other power hungry devices, like wifi or 3g chips
Re: Rapberry Pi Power
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If you are tinkering with Electronics it is handy to know
BoyOh ( Selby, North Yorkshire.UK)
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