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regarding power supply...

Posted: Wed Aug 20, 2014 4:39 pm
by prasanna_arthekar
hello.. i am totally new to raspberry pi... i have ordered this device but i am not getting appropriate power supply according to mentioned in its user manual....

Re: regarding power supply...

Posted: Wed Aug 20, 2014 4:47 pm
by DirkS
Sorry, but what is the question?
Should there have been a power supply delivered with your Pi? Or maybe a different power supply?
Or are you asking what power supply to get?

More info please...

Re: regarding power supply...

Posted: Wed Aug 20, 2014 5:39 pm
by prasanna_arthekar
prasanna_arthekar wrote:hello.. i am totally new to raspberry pi... i have ordered this device but i am not getting appropriate power supply according to mentioned in its user manual....
actually sir i am not getting power supply according to specifications...
where should i get that??

Re: regarding power supply...

Posted: Wed Aug 20, 2014 6:02 pm
by FLYFISH TECHNOLOGIES
Hi,
prasanna_arthekar wrote:actually sir i am not getting power supply according to specifications...
Specifications contain items which must be exactly fulfilled (eg. voltage) and also items listing minimal requirement (eg. current).

Which specification item and values are you talking about ?


Best wishes, Ivan Zilic.

Re: regarding power supply...

Posted: Wed Aug 20, 2014 6:33 pm
by pluggy
In simple terms the power supply is a smart phone charger with a micro USB plug with at least a 700mA output. The plain Raspberry Pi doesn't include one. They tend to vary by what country you live in.

Re: regarding power supply...

Posted: Wed Aug 20, 2014 8:45 pm
by Jim JKla
There are a lot of these around and a load that are sub spec but one that comes with either a reliable phone or a Kindle or the like are usually fine.

There are some cheap dubious ones that you will find i markets all over the worls and some of these ultra cheap ones do have a a fire risk.

There are a a bunch that just don't output enough power.

If you get one that does not have enough power you will get a rainbow block of colour on the screen if this keeps repeating it's usually a sign that you don't have enough power to sytart your RPi this won't damage your RPi but you will need to find a better PSU.

Most phone chargers are fine and there are plenty around.

The best PSU is a powered USB hub.

Re: regarding power supply...

Posted: Thu Aug 21, 2014 2:33 am
by W. H. Heydt
In the US for a Model B....
http://www.adafruit.com/products/501
(I have hopes that, at some point, Adafruit will bring out a 2+A 5.25v equivalent for the B+.)

For any Pi, including B+, for use many places...
http://swag.raspberrypi.org/collections ... wer-supply

Or....
https://www.newit.co.uk/shop/All_Cubieb ... ower-5V-2A

I will admit that I have some preference for the NewIT and Adafruit units because they don't have a fixed cable and therefore are not limited to devices with microUSB power connectors. And, indeed, if the RPF ever decided to go to a barrel connector (as the Cubieboard does, and that board comes with a USB to barrel power cable), then one wouldn't have to toss all the Pi power supplies to accomodate the new connector.

Re: regarding power supply...

Posted: Thu Aug 21, 2014 8:59 am
by kaos
W. H. Heydt wrote:I will admit that I have some preference for the NewIT and Adafruit units because they don't have a fixed cable and therefore are not limited to devices with microUSB power connectors.
Actually, I think the foundation made the right decision by choosing a supply with a fixed cable, the reason being that the cable is just as important as the power supply itself. With a loose cable, even if they had supplied a good quality one, some people would have swapped it out with a different one (either because they lost the original one, wanted a longer cable, didn't like the colour, etc.), and if they hit on an inferior cable, complained about the quality of the power supply.

Of course you can use any good quality power supply with a loose cable, but then you will also have to make sure the cable is a nice heavy gauge (by the standards of USB cables) one. Oh, and because I mentioned cable length, it shouldn't be too long either, although the heavier the gauge, the longer it can be.

--
Best regards, Kári.

Re: regarding power supply...

Posted: Thu Aug 21, 2014 9:21 am
by pluggy
The swag store PSU has to be ideal, because you have a legitimate complaint if it doesn't work with a Pi. They've been out of stock for quite a while,but are back in. I just ordered one. :)

Re: regarding power supply...

Posted: Thu Aug 21, 2014 8:18 pm
by W. H. Heydt
kaos wrote:
W. H. Heydt wrote:I will admit that I have some preference for the NewIT and Adafruit units because they don't have a fixed cable and therefore are not limited to devices with microUSB power connectors.
Actually, I think the foundation made the right decision by choosing a supply with a fixed cable, the reason being that the cable is just as important as the power supply itself. With a loose cable, even if they had supplied a good quality one, some people would have swapped it out with a different one (either because they lost the original one, wanted a longer cable, didn't like the colour, etc.), and if they hit on an inferior cable, complained about the quality of the power supply.

Of course you can use any good quality power supply with a loose cable, but then you will also have to make sure the cable is a nice heavy gauge (by the standards of USB cables) one. Oh, and because I mentioned cable length, it shouldn't be too long either, although the heavier the gauge, the longer it can be.
While I agree that those are valid points, and worthy of consideration, I also have a preferred supplier (Monoprice) for good cables (28/24 AWG). If someone is using a thin cable for whatever reason, then, as is noted, even the best power supply can have issues. In addtion, the Adafruit power supply is set up to at least partially compensate for a poor cable by being set to 5.25v.

The other advantage to a "loose cable" design is that you can also use a *shorter* cable if the outlet in use is close to the Pi. This is why I have and use various power cables ranging down to 18" in length. A fixed cable design also means a fixed cable length.

Net result is that there are advantages and disadvantages to both designs and "one size" does NOT "fit all".

Re: regarding power supply...

Posted: Thu Aug 21, 2014 8:43 pm
by rpdom
I've found Kindle chargers and cables to work without problems.

I also use "pound shop" cheap cables that I cut the ends off and joined them together with decent twin power cable. The voltage drop over a couple of cm of thin wire is not enough to cause problems, as opposed to the drop over 50cm+ of thin cable.