Kernel
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Re: Which Power Supply?

Sat Mar 03, 2012 12:58 pm

We had been told that power supplies would be sold with the Pi - and twitter says Farnell and RS have these power supplies on their site.

I just pre-ordered from Farnell after getting their email and couldn't find it tbh.

Can someone please advise if the following are ok or tell me which one they bought?

https://www.amazon.co.uk/Output-Univers ... 011&sr=1-5

https://www.amazon.co.uk/Ex-Pro%C2%AE-F ... 14&sr=1-17

https://www.amazon.co.uk/CostMad-Techno ... 06&sr=1-21

thanks

RussIT
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Re: Which Power Supply?

Sat Mar 03, 2012 1:13 pm

 got one of these along with a micro usb cable which arrived the next day

http://www.ebay.co.uk/itm/2805.....1423.l2649

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rurwin
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Re: Which Power Supply?

Sat Mar 03, 2012 1:13 pm

Yes, they are all good, although  the first two are expensive and the third doesn't have a cable (that's not unusual).

I posted links to the Farnell and RS products elsewhere on the forum today. Their prices are somewhere around £8 (plus VAT).

RussIT
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Re: Which Power Supply?

Sat Mar 03, 2012 1:18 pm

I got the micro usb cable from here

http://www.ebay.co.uk/itm/1607.....1497.l2649

Kernel
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Re: Which Power Supply?

Sat Mar 03, 2012 1:24 pm

thanks rurwin and RussIT

tried finding your post rurwin but keep getting database error - will try again later

quetzalin
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Re: Which Power Supply?

Sat Mar 03, 2012 1:41 pm

Hello!,

Im looking at this power supply but i'm not sure it will work, it gives only 550mA and the wiki recommends a ~700mA power supply.

Anyone able to confirm if it will be good enough or not?. I want to buy a power supply on Farnell for Europe.

Thanks!

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rurwin
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Re: Which Power Supply?

Sat Mar 03, 2012 1:46 pm

Model B power requirements are specified as 700mA. That may include the current for the USB ports.

Even so I would avoid that power-supply.

smuggly
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Re: Which Power Supply?

Sat Mar 03, 2012 1:55 pm

I Bought A Motorola  FMP5202a Off Ebay For $6.00 It has 850ma should be good enough for the B model? 

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sorinm
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Re: Which Power Supply?

Sat Mar 03, 2012 1:57 pm

I will use my samsung phone travel charger, 5V 700 mAh.

dawilson123
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Re: Which Power Supply?

Sat Mar 03, 2012 2:22 pm

I have a Blackberry Curve as a works mobile and by chance I happened to check the DC output from the charger; 5V @ 750mA DC. Ordered the same Blackberry charger off eBay for £6.00 delivered.

flatpack
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Re: Which Power Supply?

Sat Mar 03, 2012 2:38 pm

I was thinking of getting a powered UBS hub and using it to power the pi. Then using it as a hub as well.

Kernel
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Re: Which Power Supply?

Sat Mar 03, 2012 6:30 pm

rurwin said:


Yes, they are all good, although  the first two are expensive and the third doesn"t have a cable (that"s not unusual).

I posted links to the Farnell and RS products elsewhere on the forum today. Their prices are somewhere around £8 (plus VAT).



found the post now if anyone else needs it:

rurwin said:


Power-supplies:

Farnell

RS Components 2-pin plug (3pin are either mini-USB, low power or too expensive)

Or any mobile phone charger that supplies at least 0.7A (700mA) or preferably 1A (1000mA). Sainsburies sell them for under £5 the last time I looked.

I still have no confirmation from RS either. I've just talked to a nice lady at RS (their switchboards are jammed at 8:30 on a Saturday) and she said that the emails have not all gone out. So we still seem to be in with a chance.


Kernel
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Re: Which Power Supply?

Sat Mar 03, 2012 6:44 pm

So about power supplies that supply more then 1 amp? will they be able to provide enough power for extra usb components or are there limits on the usb ports in how much power can pass through the board?

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abishur
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Re: Which Power Supply?

Sat Mar 03, 2012 7:26 pm

Kernel said:


We had been told that power supplies would be sold with the Pi - and twitter says Farnell and RS have these power supplies on their site.



Actually, we've been told quite the opposite I fear.  We've been told that we will need to provide our own PSU Kernel said:


So about power supplies that supply more then 1 amp? will they be able to provide enough power for extra usb components or are there limits on the usb ports in how much power can pass through the board?



I personally plan on using a slightly more than needed PSU.  Basically there are always two things to look at when it comes to a PSU, voltage and Amps.  Voltage is consistent (more or less ) so a 5V PSU will do it's best to consistently provide 5V.  Amperage on the other hand is more of a "as needed" number.  It will provide however many amps you need up to the maximum amount it can (300 mA, .5A, or 1A) as such then, you can get a 5V 50A PSU and you won't damage the board as it will only take the .7A it needs (obviously though, this means that the other 49A go to waste and you wasted your money buying such a beefy PSU).

There is a limit on the USB ports.  There's a fuse which shuts off the draw at 140 mA.  That's more than enough for a keyboard/mouse or even a wifi adapter, but you won't be powering a Hard drive off them
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Joe Schmoe
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Re: Which Power Supply?

Sat Mar 03, 2012 7:39 pm

Kernel said:


So about power supplies that supply more then 1 amp? will they be able to provide enough power for extra usb components or are there limits on the usb ports in how much power can pass through the board?



Best information is that the board itself can never draw/supply more than 1A, because of the 1A polyfuse on the board.  As I understand it, the power draw is as follows:

1) Board itself (i.e., model A or B): 300ma

2)  Ethernet (on the B): 230ma (max).  Note that the ethernet is one of the 3 USB ports.

So, at least for the B, the max draw on the other 2 USB posts is 470ma (regardless of how much the PSU could, theoretically, supply).
And some folks need to stop being fanboys and see the forest behind the trees.

(One of the best lines I've seen on this board lately)

Ren
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Re: Which Power Supply?

Sat Mar 03, 2012 7:57 pm

Any opinions on this?

http://www.suntekstore.co.uk/g.....d=14002339

So could power it via a set of 18650 lithiums.

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rurwin
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Re: Which Power Supply?

Sat Mar 03, 2012 8:29 pm

So far as I can see it should work. I don't like that line about identification resistor, which I don't understand.

Kernel
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Re: Which Power Supply?

Sat Mar 03, 2012 8:51 pm

Abishur said:

Actually, we've been told quite the opposite I fear.  We've been told that we will need to provide our own PSU
The FAQ says:
What are the power requirements?

The device is powered by 5v micro USB. You can read more about it here. Power supplies will be available at launch.

I had understood this as meaning they would have been in the raspberrypi.com store (when the plan was to sell them through there) (aswell as SD cards with preloaded OS) but yes you are right it doesn't actually say that it just says they will be available



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Chromatix
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Re: Which Power Supply?

Sat Mar 03, 2012 8:53 pm

rurwin said:


So far as I can see it should work. I don't like that line about identification resistor, which I don't understand.


The ID resistor is to tell a device which can act as both a USB device and a USB charging target (eg. a phone or camera) that it's connected to a charger an can therefore draw more current than standard USB permits.
The key to knowledge is not to rely on people to teach you it.

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sorinm
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Re: Which Power Supply?

Sat Mar 03, 2012 8:57 pm

The cheapest solution for a PS is to get a Nokia AC-10E charger. It`s output is 1200 mAh, more than needed.

Kernel
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Re: Which Power Supply?

Sat Mar 03, 2012 9:31 pm

sorinm said:


The cheapest solution for a PS is to get a Nokia AC-10E charger. It`s output is 1200 mAh, more than needed.



are phone chargers designed to be used for extended periods? i.e. most people switch them off when the phone is charged/aren't charging 24/7 whilst someone might want to have their raspi switched on 24/7

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Chromatix
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Re: Which Power Supply?

Sat Mar 03, 2012 9:41 pm

On the contrary, most people leave their phone chargers plugged in 24/7.  The green league are having a devil of a time convincing people to do otherwise.
The key to knowledge is not to rely on people to teach you it.

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sorinm
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Re: Which Power Supply?

Sat Mar 03, 2012 9:42 pm

Normally raspi model B will use maximum 700 mAh so that charger won`t be under heavy load. Probably it won`t be any problem to use a solid phone charger for extensive periods of time.

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sorinm
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Re: Which Power Supply?

Sat Mar 03, 2012 9:47 pm

Chromatix said:


On the contrary, most people leave their phone chargers plugged in 24/7.  The green league are having a devil of a time convincing people to do otherwise.



This is true but the charger isn`t under load 24/7. It`s plugged in the socket but won`t charge any device. I think chargers around 700-800 mAh are not recommended for 24/7 use. Use a more capable charger that won`t be used at 100% capacity.

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Re: Which Power Supply?

Sat Mar 03, 2012 9:59 pm



can i use this with  a USB to Micro USB cable to power the RaspberryPi, with usb stuff hdmi pluged in etc ...
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