nullstring
Posts: 178
Joined: Sun Oct 02, 2011 3:05 pm

Re: Which Power Supply?

Mon Mar 05, 2012 6:17 pm

For those in the USA, amazon has the Nokia AC-10U for $9.39.

This is the cheapest 1+ amp charger I've seen so far.

http://www.amazon.com/Nokia-Or.....8;sr=1-1 

(I will only be buying from stores I can guarantee to be authentic, like amazon. I'm not interested in ebay or amazon market place prices. This PSU will be running 24/7, and it would be a disaster to have it catch fail or catch fire).

drgeoff
Posts: 10205
Joined: Wed Jan 25, 2012 6:39 pm

Re: Which Power Supply?

Mon Mar 05, 2012 6:22 pm

Sorin said:


Isn`t that usb hub delivering only 500 mAh per usb port ? Model B needs a minimum of 700 mAh to power it.


Even if it is only delivering 500 mA (NB NOT mAh) per port a swift attack with a soldering iron will soon sort that out.

User avatar
sorinm
Posts: 138
Joined: Sat Mar 03, 2012 10:41 am
Location: Romania

Re: Which Power Supply?

Mon Mar 05, 2012 6:24 pm

in Romania is mAh

drgeoff
Posts: 10205
Joined: Wed Jan 25, 2012 6:39 pm

Re: Which Power Supply?

Mon Mar 05, 2012 6:43 pm

Sorin said:


in Romania is mAh


Either you are guilty of false representation of the facts or Romania is out of step with the rest of the world  :-(

Current is amps = A.  milliamp = mA = 1A/1000

Capacity Ah is current (A) multiplied by time in hours (h).

Hence rechargeable car batteries marked eg 60 Ah, rechargeable AA cells 2500 mAh.

Power supplies marked 800 mA.

ruud
Posts: 3
Joined: Fri Dec 30, 2011 2:25 pm

Re: Which Power Supply?

Mon Mar 05, 2012 6:49 pm

Alex said:

But there are good options, like this one: 5V,1.2A whit a usb/micro usb cable.
Or this one (5V, 1.2A, microUSB connector), which doesn't require a separate USB/micro-USB cable.

User avatar
sorinm
Posts: 138
Joined: Sat Mar 03, 2012 10:41 am
Location: Romania

Re: Which Power Supply?

Mon Mar 05, 2012 6:51 pm

drgeoff you are right, my mistake !

ruud
Posts: 3
Joined: Fri Dec 30, 2011 2:25 pm

Re: Which Power Supply?

Mon Mar 05, 2012 7:03 pm

tbar said:


Kernel said:


rurwin said:


Power-supplies:

Farnell

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



This one looks promising. I haven't been able to find a cable on RS' website which can be used with this PSU and the RPi. Can anybody help?


RS Components: 3-pin plug (UK), 5V, 1.2A, micro USB connector
RS Components: 2-pin plug (EU), 5V, 1.2A, micro USB connector

drgeoff
Posts: 10205
Joined: Wed Jan 25, 2012 6:39 pm

Re: Which Power Supply?

Mon Mar 05, 2012 7:08 pm

ruud said:


Alex said:


But there are good options, like this one: 5V,1.2A whit a usb/micro usb cable.


Or this one (5V, 1.2A, microUSB connector), which doesn't require a separate USB/micro-USB cable.


Be aware that if you are planning to use a 1A fused shaver adaptor to convert these and similar 2 pin PSUs to fit a UK 13A mains socket, sooner or later the inrush current may blow the 1A fuse.  Been there, done that.

plugwash
Forum Moderator
Forum Moderator
Posts: 3517
Joined: Wed Dec 28, 2011 11:45 pm

Re: Which Power Supply?

Mon Mar 05, 2012 7:20 pm

Abishur said:


That's kinda half my question, will an apple charger deliver the current without the device requesting for more?


I don't have one to hand to test but i'd be very surprised if it didn't.

jamieoliver22
Posts: 22
Joined: Sat Mar 03, 2012 2:19 am

Re: Which Power Supply?

Mon Mar 05, 2012 9:24 pm

I've bought one of these from Amazon - 5V 700mAh. I thought this would be good enough, but reading this thread I wish I had bought a slightly more powerful one. But nevermind, it will still work :p

http://www.amazon.co.uk/dp/B00.....B0028QHJSK

User avatar
abishur
Posts: 4477
Joined: Thu Jul 28, 2011 4:10 am
Location: USA
Contact: Website

Re: Which Power Supply?

Mon Mar 05, 2012 10:04 pm

plugwash said:


Abishur said:


That's kinda half my question, will an apple charger deliver the current without the device requesting for more?


I don't have one to hand to test but i'd be very surprised if it didn't.



I would be as well and most of this is just me thinking out loud.  It's rather annoying that with something with so many standards, there's still so much fluctuation both on how its implemented and how "smart" devices are in requesting and providing power
Dear forum: Play nice ;-)

drgeoff
Posts: 10205
Joined: Wed Jan 25, 2012 6:39 pm

Re: Which Power Supply?

Thu Mar 08, 2012 11:36 am

drgeoff said:


Sorin said:


Isn`t that usb hub delivering only 500 mAh per usb port ? Model B needs a minimum of 700 mAh to power it.


Even if it is only delivering 500 mA (NB NOT mAh) per port a swift attack with a soldering iron will soon sort that out.



That hub has now been delivered.  Good news and bad news!

The 5 volt input to the hub goes directly to all the 8 USB sockets - no current limiting devices of any kind.

The 8 USB sockets above include the "input" one. That means that 5 volts from the hub will go back towards the RP if this hub is used to extend one of the RP's USBs.  If the RP is not getting 5 volts on its micro-USB the RP will try to draw up to 700mA from the USB "output" socket.  There is thought to be a 140mA polyfuse in circuit so that fuse will open.  Ideally the hub should be modified - it needs two track cuts and a bypass wire to do that.

The power supply is only 1000mA so that doesn't leave much for other USB powered peripherals.

The hub's PCB has provision for 6 electrolytic capacitors across the 5 volt supply.  None are fitted.

Considering the price (£3.48 delivered in UK) it is OK for those who can work with its limitations but as general solution for keyboard junkies* I cannot recommend it.

(* my term for software gurus who know nothing about hardware.)

MattCook
Posts: 16
Joined: Tue Feb 21, 2012 1:46 pm
Location: S. Manchester

Re: Which Power Supply?

Thu Mar 08, 2012 11:55 am

<keyboard_junkie_mode>

I would not have known even to check such stuff, so thank you.  Would the best (safest) plan be to power the board from a phone charger, and then use something akin to a D-Link DUB-H7 to hook mouse/keyboard/usb disks/sticks/card readers etc into ?

</keyboard_junkie_mode>

Matt

User avatar
Tass
Posts: 535
Joined: Sat Jan 21, 2012 11:15 am

Re: Which Power Supply?

Thu Mar 08, 2012 12:00 pm

Agreed MattCook.

@drgeoff - thanks for all this info.  As this is all a little over my head I'll sit back and wait for you to test it all out, and once I know the end result won't be burnt Pi, I might do that.  For now, a separate mobile charge will do the trick for me.

Not that I don't believe you, but the idea of the Pi being powered by it's USB port doesn't seem to be widely sanctioned by the Foundation/community.  I might be way of the mark here, or just a little paranoid due to fear of the unknown.

texy
Forum Moderator
Forum Moderator
Posts: 5161
Joined: Sat Mar 03, 2012 10:59 am
Location: Berkshire, England

Re: Which Power Supply?

Thu Mar 08, 2012 12:35 pm

I didn't buy the hub to power the RPi, just to extend the USB connectivity,

as once the keyboard and mouse are connected, there is none spare

However, if the input could be utilised in conjunction with one of the outputs in order for the hub to also power the RPi, then it could be more useful in certain circumstances.

Texy
Various male/female 40- and 26-way GPIO header for sale here ( IDEAL FOR YOUR PiZero ):
https://www.raspberrypi.org/forums/viewtopic.php?f=93&t=147682#p971555

Witchdoctor
Posts: 1
Joined: Thu Mar 08, 2012 7:14 pm

Re: Which Power Supply?

Thu Mar 08, 2012 7:23 pm

wifiuk said:


its not "too much" is it?



If a device requires 750 ma then you need to provide at least that amount.  Providing more current is not a problem.  The device will only draw what it needs.  Providing less than that amount will result in erratic performance.

However the same is not true of the voltage.  This device requires 5 volts.  Providing more than 5 volts would burn out your device and providing less will result in the device behaving erratically.

WD

Deedee
Posts: 4
Joined: Wed Jan 11, 2012 10:57 am

Re: Which Power Supply?

Thu Mar 08, 2012 8:08 pm

May i please make a suggestion about both Power Supplies and SD cards.

There are so many threads about these and postings it can be awkward enough for some one with a little knowledge to follow.

Would it not be better to have a section pinned on the forum where simple information such as what, where and how much a suitable psu can be posted, and as important, what NOT to buy?

The same goes double for SD cards i think some of the experienced people in here are still scratching their heads over, and so again this information on what to buy and what Not to buy. I know nothing will be clear until we really have the device in our hands, but im sure there and some clear good and bad candidates already known of.

This would at least give people now and in the future a first place to go and look, and lets face it, out side a display, these are the two remaining things you need to run this device and the info should be more or less clearly available at your finger tips without having to read a hundred posts for some thing so critical to function.

With a VERY patient simle......

User avatar
abishur
Posts: 4477
Joined: Thu Jul 28, 2011 4:10 am
Location: USA
Contact: Website

Re: Which Power Supply?

Thu Mar 08, 2012 10:52 pm

Well there is the wiki which pretty much does just that
Dear forum: Play nice ;-)

Kernel
Posts: 395
Joined: Sat Mar 03, 2012 12:53 pm

Re: Which Power Supply?

Fri Mar 16, 2012 7:18 pm

how about this as a portable supply? https://www.amazon.co.uk/Belkin-F8M160c ... 005HALE7Q/

or this to power in the car: https://www.amazon.co.uk/Belkin-Micro-U ... pd_cp_ce_2

though one reviewer says:


Update: Did some research on this issue. It turn out there is an international standard for delivering charge to a mobile device via USB. This requires the device to ask the power source for permision to draw power if the device is a dumb device (such as this one) then it should "short out pin's 2 and 3 (D+ & D-) with a resistance of no more than 200 ohms". This device does not do this, hence won't work with a device that complies with the standard. Nokia devices appear to comply with the standard and Apple devices don't.


User avatar
Montala
Posts: 675
Joined: Mon Mar 05, 2012 11:54 pm
Location: Herefordshire (U.K.)

Re: Which Power Supply?

Fri Mar 16, 2012 7:40 pm

Kernel said:


how about this as a portable supply? https://www.amazon.co.uk/Belkin-F8M160c ... 005HALE7Q/


It is nearly £60 though!

nicknml
Posts: 200
Joined: Thu Mar 15, 2012 8:44 pm

Re: Which Power Supply?

Fri Mar 16, 2012 7:58 pm

I plan to use my bluetooth headset charger for model b which outputs 700mA.  I'm thinking that it should be enough power as the keyboard and mouse that I plan to use consume 150mA combined.

Kernel
Posts: 395
Joined: Sat Mar 03, 2012 12:53 pm

Re: Which Power Supply?

Fri Mar 16, 2012 8:49 pm

Montala said:


Kernel said:


how about this as a portable supply? https://www.amazon.co.uk/Belkin-F8M160c ... 005HALE7Q/


It is nearly £60 though!



Yes expensive but so are quite a few of the other things mentioned in the forum such as screens - though something like this wouldn't be something that 99% of people would buy anyway - only for someone who needs a truly portable supply such as this

SvenP
Posts: 8
Joined: Sat Feb 11, 2012 8:48 pm

Re: Which Power Supply?

Fri Mar 16, 2012 9:25 pm

Guided by Sorin's posting above I picked up some Nokia AC-10E locally for SEK 19.00 (= £1.78) each.

Thank you very much for the tip Sorin!

arm2
Posts: 253
Joined: Thu Dec 15, 2011 3:46 pm

Re: Which Power Supply?

Sat Mar 17, 2012 8:38 am

RussIT said:


I got the micro usb cable from here

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



If that works reliable at 700mA I'll eat my hat!

Generally you get what you pay for 99p inc VAT & Postage!!!

robleady
Posts: 34
Joined: Thu Jan 12, 2012 10:24 pm

Re: Which Power Supply?

Sat Mar 17, 2012 9:00 am

I've been thinking about this one:

http://www.usbnow.co.uk/Hubs-7....._info.html

Not particularly cheap, but looks pretty nice...

Regards,

Rob

Return to “General discussion”