Having trouble finding a good power supply for the raspberry pi 2

You did not specify but it needs to be  a 2.5" hard drive. The biggest problem with supplying a hard drive with power is when you

first turn it on. It takes a lot more current to "spin up" the disks in the drive than it does to keep them spinning. I have a 160 GB 2.5"

hard drive that takes 1.1 A to start up and about 400 mA (0.4 A) when reading or writing to give you some idea of the difference.

Another very common problem when using USB chargers that require a separate USB "data" cable to supply the power is that the

cable does not use wire that will carry that much current without dropping voltage due to the resistance of the wire. Most USB

cables I have seen use 26 or 28 gauge wire (the smaller the gauge number the thicker the wire, this is usually printed on the cable

but it may also be only on the packaging) and it seems fairly constant that longer cables (6') use the thinner wire and short cables (3')

use the thicker wire.

If you are in the states I have found that MCM electronics has a 5V 2A power supply for the Raspberry Pi that uses 22 gauge wire

for $4.99 that works fine with the previously mentioned 160 GB hard drive.

@Clem

A USB keyboard should use less that 80 mA (0.08A) and a mouse probably about the same. I'm not sure how much current is needed

for wireless keyboards and mice but it should not be much more.

You did not specify but it needs to be  a 2.5" hard drive. The biggest problem with supplying a hard drive with power is when you

first turn it on. It takes a lot more current to "spin up" the disks in the drive than it does to keep them spinning. I have a 160 GB 2.5"

hard drive that takes 1.1 A to start up and about 400 mA (0.4 A) when reading or writing to give you some idea of the difference.

Another very common problem when using USB chargers that require a separate USB "data" cable to supply the power is that the

cable does not use wire that will carry that much current without dropping voltage due to the resistance of the wire. Most USB

cables I have seen use 26 or 28 gauge wire (the smaller the gauge number the thicker the wire, this is usually printed on the cable

but it may also be only on the packaging) and it seems fairly constant that longer cables (6') use the thinner wire and short cables (3')

use the thicker wire.

If you are in the states I have found that MCM electronics has a 5V 2A power supply for the Raspberry Pi that uses 22 gauge wire

for $4.99 that works fine with the previously mentioned 160 GB hard drive.

@Clem

A USB keyboard should use less that 80 mA (0.08A) and a mouse probably about the same. I'm not sure how much current is needed

for wireless keyboards and mice but it should not be much more.

Would this one work? 5V 2A Power Supply w/ 20AWG 6' MicroUSB Cable - International ID: 2297 - $14.95 : Adafruit Industries, Unique & fun DIY …

It's a little expensive but it should work just fine. I have bought several items from Adafruit and have found them to be good quality products.

Sounds to me like a good choice. Let us know when you get it working. TY

I'll be buying and trying this out next month. Thanks. I'll let you guys know if this worked or not when I get the chance.

You need to be aware that this power supply outputs 5.3V even though it is rated on the cover of the brick as 5V, Adafruit has deliberatly done this to ensure that at max current with attached cable your still getting 5V at the connector.

5.3V technically EXCEEDS the high limit of 5V logic which is normally rated as 5V +- 5% and that means 4.75V - 5.25V. Generally this should not present any problems but you need to be aware of this as if your only drawing the minimal current then your running the PI at its upper voltage limits.

Most of the logic on the PI actually runs at 3V3 and it has a nice SMPS to get that so it should be tollerent of this higiher voltage. Added devices on the GPIO may not be so forgiving.

Regards

Peter

From what I see, HDD, WiFi, and DVB's seem to need more current than keyboards, mice(wired), and solid state USB sticks.

gdstew is that not this:

A USB keyboard should use less that 80 mA (0.08A) and a mouse probably about the same. I'm not sure how much current is needed

for wireless keyboards and mice but it should not be much more.

TY,

Clem

Yes, I was just being a little more specific to show how much difference there is between a hard drive and USB keyboards/mice. Wireless keyboards/mice

use a lot less power that WiFi because they are used at much shorter ranges.