Which Power Supply?


102 posts   Page 4 of 5   1, 2, 3, 4, 5
by Isceald Glede » Sat Mar 17, 2012 3:11 pm
I am going for power over ethernet. The switch below (from play.com) can power 4 ?'s, one splitter (from novatech) needed per ? and I have to find a jack plug to micro usb cable from somewhere. Play.com don't do splitters and novatech only have expensive PoE switches. After all the hassle needed to find those two distributors I am not shocked that the cable has to come from somewhere else.

TP-Link TL-SF1008P 8-port 10/100M PoE Switch

TP-Link TL-POE10R Power Over Ethernet Splitter

http://www.bnpcs.com have HDMI to VGA converters (Part number 466767-ZH1), but they cost about 2 ?'s.
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by milhouse » Tue Mar 27, 2012 1:37 am
Sorin said:


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



Just to say that for the UK, the equivalent Nokia charger (with 3-pins) is the AC-10X - same 1200mA output, and dirt cheap on Amazon or play.com for under £4 each.
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by RaTTuS » Tue Mar 27, 2012 7:18 am
Isceald Glede said:


I am going for power over ethernet. The switch below (from play.com) can power 4 ?'s, one splitter (from novatech) needed per ? and I have to find a jack plug to micro usb cable from somewhere. Play.com don't do splitters and novatech only have expensive PoE switches. After all the hassle needed to find those two distributors I am not shocked that the cable has to come from somewhere else.

TP-Link TL-SF1008P 8-port 10/100M PoE Switch

TP-Link TL-POE10R Power Over Ethernet Splitter

http://www.bnpcs.com have HDMI to VGA converters (Part number 466767-ZH1), but they cost about 2 ?'s.



http://www.play.com/PC/PCs/4-/.....oduct.html

but POE does not work on RPi - or does this do dsoemthing else
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by rurwin » Tue Mar 27, 2012 7:29 am
The RPi cannot take its power from the Ethernet socket, but power can be put on the CAT5 cable and then split off before it gets to the RPi. That means that the RPi does not need to be close to a power outlet and there is only one cable to be run.

However, there needs to be a power splitter and a regulator external to the RPi but alongside it.
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by daka » Tue Mar 27, 2012 9:29 am
Deedee said:


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......



I have a Huawei mobile modem power supply with a mini usb plug but the voltage is 5.3.  Does anyone know if this excess voltage would damage the unit?

cheers

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by john_wage » Tue Mar 27, 2012 10:31 am
daka said:


I have a Huawei mobile modem power supply with a mini usb plug but the voltage is 5.3.  Does anyone know if this excess voltage would damage the unit?


Generally speaking, no it won't directly damage the unit. I don't know exactly what kind of voltage regulators they use but even in the lack of any regulators (which is impossible) then 0.3V over voltage is not enough to damage any components, with some extreme bad luck you would get an unstable system or unpredictable behavior.
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by grondinm » Tue Mar 27, 2012 10:53 am
i purchased this USB hub to simply extend the usb ports of my pi.

http://dx.com/powered-7-port-u.....uded-18538

then i though maybe i can power the pi with it. I am trying to find out how much power each port outputs so far no luck. if it don't work then i will just use my cell phone charger.
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by john_wage » Tue Mar 27, 2012 11:22 am
grondinm said:


then i though maybe i can power the pi with it. I am trying to find out how much power each port outputs so far no luck. if it don"t work then i will just use my cell phone charger.


Generic USB hubs that have their own AC adapter will usually allow devices to draw as much current as they want right off-the-bat up to 1A or more.

So my guess is yes you can power the RPi from that USB hub.

USB power from a PC's USB jack will not work as those are by standard 100mA for all devices and maximum 500mA can be allowed after negotiation with the hardware..
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by alexeames » Tue Mar 27, 2012 11:40 am
Deedee said:


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......



The forum is being changed soon to a better system. If any more stickies are created before then it will cover almost the whole of the first page, rendering the forum practically unusable. What is really needs is separate sections. But there's no point doing any work on this one when it's going to be changed soon. :)
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by drgeoff » Tue Mar 27, 2012 11:55 am
grondinm said:


i purchased this USB hub to simply extend the usb ports of my pi.

http://dx.com/powered-7-port-u.....uded-18538

then i though maybe i can power the pi with it. I am trying to find out how much power each port outputs so far no luck. if it don"t work then i will just use my cell phone charger.



That hub is the same one as discussed at http://www.raspberrypi.org/for.....sb-hubs.  See posts 7, 8 and 9.  The PSU supplied with yours may be different.  The power input socket on the hub is wired directly to the 7 "extension" sockets and to the USB "input" socket which is a bit naughty.  I sent mine back.
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by john_wage » Tue Mar 27, 2012 12:11 pm
Yeah, it's unfortunate you can't really give the green light on a product that you can't physically test..

You can really only guarantee "it will work IF it does what it's supposed to do".. sadly that is not the case for many devices on the market.
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by daka » Tue Mar 27, 2012 3:06 pm
grondinm said:


i purchased this USB hub to simply extend the usb ports of my pi.

http://dx.com/powered-7-port-u.....uded-18538

then i though maybe i can power the pi with it. I am trying to find out how much power each port outputs so far no luck. if it don"t work then i will just use my cell phone charger.



Thanks for the reply grondinm

sean
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by JLB » Tue Apr 17, 2012 3:49 pm
Isceald Glede said:


I am going for power over ethernet. The switch below (from play.com) can power 4 ?'s, one splitter (from novatech) needed per ? and I have to find a jack plug to micro usb cable from somewhere.

TP-Link TL-SF1008P 8-port 10/100M PoE Switch

TP-Link TL-POE10R Power Over Ethernet Splitter


Did you find a DC jack to micro usb cable? If so, could you share the links?

Planning on going down the same route you have taken. Cheers
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by plugwash » Tue Apr 17, 2012 4:11 pm
I suspect you will have to get out the soldering iron and make the cable to connect the Pi to the splitter.
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by abishur » Tue Apr 17, 2012 4:21 pm
plugwash said:


I suspect you will have to get out the soldering iron and make the cable to connect the Pi to the splitter.



+1

If solder isn't an option for you, you can also twist cap, electrical tape, or even hot-glue the wires together as long as you make sure to connect the right wires together and you make sure to insulate them properly when you are done.  You'll need to look at your PSU, but generally speaking the center wire is insulated and positive, surrounding the center wire is a bunch of thin copper wires, twist all these together and *generally* you have your negative wire.  On the micro usb side pin 1 (usually red) is your positive wire, and pin 5 (usually black) is your ground wire (typically there are only 4 wires as pin 4 is typically connected to pin 5)
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by JLB » Tue Apr 17, 2012 4:51 pm
plugwash said:


I suspect you will have to get out the soldering iron and make the cable to connect the Pi to the splitter.



Don't mind getting the old soldering iron out, but think I have another solution

Tp-Link TL-POE10R PoE Splitter-> DC 3.5mm 5V Male to USB Male -> Micro USB female to Mini USB male adapter -> Raspberry Pi

Anyone have any reasons why this shouldn't work? The only reason I am doing this I wish to attach to a mounted TV in the kitchen which has one ethernet cable which has POE and no plugs available.

http://www.play.com/PC/PCs/4-/.....fer=search

http://www.amazon.co.uk/1211-Q.....B004BVOXTS

http://www.amazon.co.uk/Starte.....B002O1S8IE
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by selsinork » Tue Apr 17, 2012 5:15 pm
JLB said:



Tp-Link TL-POE10R PoE Splitter-> DC 3.5mm 5V Male to USB Male -> Micro USB female to Mini USB male adapter -> Raspberry Pi

Anyone have any reasons why this shouldn't work? The only reason I am doing this I wish to attach to a mounted TV in the kitchen which has one ethernet cable which has POE and no plugs available.


Only going by the pics, but the splitter looks like it's got a 2.1mm or 2.5mm power out socket. The 3.5 - USB cable doesn't look like it'll fit into that.

The cable also looks to have a normal USB A connector on the other end.

Your adapter appears to have a micro usb socket which a normal USB A isn't going to fit.

Also that adapter looks to be the opposite to what you need, the plug end is mini usb where you'd need it to be micro usb.

Don't get me wrong, it's a perfectly valid idea to to something like this, I'd just check that all your adapters and cables fit together properly.  From those pics, it doesn't look like it to me.
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by JLB » Tue Apr 17, 2012 7:36 pm
Yes you are correct, a bit of googling, the jack is 2.5mm on the splitter and I posted the wrong link for the adapter, need USB -> Micro

Thanks for spotting my mistakes :)
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by ThePunisher1024 » Sat Apr 21, 2012 1:33 pm
So 700ma is the absolute maximum the Pi will draw with ethernet connected, and 2 USB devices drawing full power, and the Pi itself drawing the maximum amount of power it can?
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by gingbeard » Sat Apr 28, 2012 10:43 am
After reading that its not a good idea to power the pi from a USB hub/PC I have bought http://www.ebay.co.uk/itm/330717731492 ready for my pi to be delivered. Arrived next day
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by Eoin » Sun Jun 02, 2013 7:21 pm
Previously I used a generic 700mA USB PSU and was having a few issues when adding more peripherals.

I have had no such issues since replacing it with a Minwa MWUSB3UK, 2.1A costing £7.
http://cpc.farnell.com/jsp/search/productdetail.jsp?SKU=PW03050

Now running combined USB keyboard and touchpad, PiFace daughter board, and pendrive.
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by rurwin » Sun Jun 02, 2013 8:48 pm
ThePunisher1024 wrote:So 700ma is the absolute maximum the Pi will draw with ethernet connected, and 2 USB devices drawing full power, and the Pi itself drawing the maximum amount of power it can?

It's rather an old post, but since the thread has been resurrected...

Not quite. 2 USB devices drawing full power would be 1A (1000mA). The Pi was only designed to supply 100mA from each USB port. It is less limited now since the fuses have been removed on the rev2 boards, but full USB power would trigger the power input fuse. If you want to use thirsty devices a powered USB hub is required.

700mA was specified with the 100mA per USB port limit in mind.
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by kevinthefixer » Sun Jun 02, 2013 11:07 pm
Just ordered my model B. As someone else said, I plan to power it from a powered USB hub. Its output is well regulated, the wall-wart puts out 7.5V@2.1A but the USB 5V buss measures 4.96V at no load. My question is whether or not I will be able to take power down the data cable designed to run from the RPi to the root of the hub, or will I need to run another micro-USB cable from one of the other ports to the power jack on the RPi? Somewhere in the FAQs it mentions a board schematic to be released which should tell us that but maybe someone has already tried it?
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by plugwash » Mon Jun 03, 2013 1:54 am
kevinthefixer wrote:Just ordered my model B. As someone else said, I plan to power it from a powered USB hub. Its output is well regulated

How do you know?

, the wall-wart puts out 7.5V@2.1A but the USB 5V buss measures 4.96V at no load.

Measuring the no load voltage is not enough to test regulation, you also need to measure the full load voltage.

My question is whether or not I will be able to take power down the data cable designed to run from the RPi to the root of the hub, or will I need to run another micro-USB cable from one of the other ports to the power jack on the RPi?

Recent model Pis don't care which direction the 5V on it's power rail comes from. They are perfectly happy with it coming from the micro USB power port, one of the USB downstream ports or the GPIO header.

The question is do you have a cheap and cheerful hub that violates the USB spec and feeds power back to it's host connector (and hence can power the Pi that way) or do you have a compliant USB hub.
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by kevinthefixer » Mon Jun 03, 2013 2:50 am
Measuring the no load voltage is not enough to test regulation, you also need to measure the full load voltage.


True enough. I was only thinking of overvoltage and didn't think to come up with a load for it. Maybe next weekend.

Recent model Pis don't care which direction the 5V on it's power rail comes from. They are perfectly happy with it coming from the micro USB power port, one of the USB downstream ports or the GPIO header.


That was what I was wondering.

The question is do you have a cheap and cheerful hub that violates the USB spec and feeds power back to it's host connector (and hence can power the Pi that way) or do you have a compliant USB hub.


This old Belkin probably predates the standards. I couldn't find any data at all on it and I don't have a stub USB-B end to test it with. Once my shiny new RPi shows up it'll be easy enough to plug it in and see. I chose this one because (1) I had it and (2) it has a clear case like what I plan for the RPi and (3) looked like a more-than-adequate power supply, with a clearly-visible power FET to regulate it. It also has a switch labeled self--bus on it that should serve as an on-off switch for the system.

Thanks for the prompt and informative response!
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