s1ck
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power supply options for multiple PIs

Tue Jul 29, 2014 7:38 am

Hello,

I'd like to build a small demo cluster for some research and educational purpose using Raspberry or Banana Pis (mostly because of the processor and the 1GB RAM). I'm a computer scientist and not so familiar with electrical engineering. I was looking into different solutions like for example that one using Cubieboards: http://www.cubietruck.com/blogs/news/13 ... ubieboards or that one using Rasperry PIs: http://coen.boisestate.edu/ece/raspberry-pi/ I think what the first one uses is a Single Output PSU like that one: http://goo.gl/q0zO8P the latter uses a standard ATX PSU.
I ordered a Raspberry Pi and a Banana Pi for testing the software side (arch linux, java). If these tests are successful, I'd like to add more nodes without buying multiple USB power supplies, so a scalable solution is needed. What do you guys think about the Single Output PSU for powering maybe up to 20 Raspberry / Banana Pis, how could i get the power from the PSU to the PIs? Are there maybe other options I am not thinking of? Thanks for your time and help!

Regards, Martin

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RaTTuS
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Re: power supply options for multiple PIs

Tue Jul 29, 2014 8:13 am

something like

Code: Select all

http://www.ebay.co.uk/itm/DC-5V-12V-24V-Universal-Regulated-Switching-Power-Supply-For-LED-Strip-CCTV-UK-/271523830300?
5V 20A
will do >20 RPi's and cameras

or use that to power 4 USB hubs and power 4 RPI's from each hub
make sure you get a 5V version

get good quality micro USB leads
and get B+'s [for better power management]
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s1ck
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Re: power supply options for multiple PIs

Tue Jul 29, 2014 8:45 am

Thanks for the quick reply! What would be a good and safe way to connect that PSU to the PIs? What I can see from the picture is that there are just some screws to connect cables on the back side of the PSU. So I guess I just connect two cables (5V and mass) to a micro USB plug which goes into the PI? Sorry for my noob questions. Thanks again!

Edit: speaking of USB hubs .. this could also be an option? http://www.amazon.com/Anker-Aluminum-13 ... b+hub+2.5A

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Re: power supply options for multiple PIs

Tue Jul 29, 2014 8:57 am

You might be better off powering via the GPIO's in this case - easier to make up multiple cables etcs and may make cable routing easier.
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RaTTuS
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Re: power supply options for multiple PIs

Tue Jul 29, 2014 9:00 am

they usually come with
5 screw terminals

mains Live , Neural and Earth
then
V- and V+

wire a mains plug into the 1st 3
then wire the +V and -V to a easy distribution block [one input and several out's - to make it easy for you later]

then you have several choices
either wire micro usb leads [butcher a cable or two ] to power the RPI directly and wire +V to read an -V to black
or wire the input from the USB hubs to the block [ butcher their leads or get screw adapters like

Code: Select all

http://www.ebay.co.uk/itm/10x-DC-Power-Jack-Connector-Male-CCTV-12v-CABLE-ADAPTOR-PLUG-CCTV-DVR-Camera-/281162277470
depending on what the USB hubs need]
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RaTTuS
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Re: power supply options for multiple PIs

Tue Jul 29, 2014 9:03 am

[quote="s1ck".. http://www.amazon.com/Anker-Aluminum-13 ... b+hub+2.5A[/quote]
very expensive for that it is
if you have a 10A PSU and model B+ then you will have no real need for a USB hub - I mentioned them as you can use them to power several RPI's via the Micro usb leads

powering via the GPIO is possible also but you are bypassing the power protection on the RPI
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s1ck
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Re: power supply options for multiple PIs

Tue Jul 29, 2014 9:10 am

Thanks! The guy who built that cluster (http://goo.gl/F4nMHB) also used the GPIO, but according to my electrical experience this would result in burned houses I guess. Using the USB Hub as the only power supply is not an option, right? Because the total current (5A) would not be enough. So I'll look deeper into the PSU option RaTTuS described.

s1ck
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Re: power supply options for multiple PIs

Tue Jul 29, 2014 9:21 am

@RaTTuS the construction you described is similar to that one, right? http://binaryfury.wann.net/tinycluster/ except the ATX PSU. And he is using the GPIO port (can be seen in that picture https://flic.kr/p/dTQDqV).

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RaTTuS
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Re: power supply options for multiple PIs

Tue Jul 29, 2014 9:49 am

yeah It's easier to get GPIO leads to power the RPI's
but I don't have issues with micro USB [well apart from attempting to solder them up ....] so pre bought ones are better ;)
ATX PSU's are generally more expensive [unless you have one laying around], and can be nosier [YMMV] and come with extra leads and +12V as well as +5V - so may or may not be better...
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s1ck
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Re: power supply options for multiple PIs

Tue Aug 05, 2014 7:48 am

So this is the current state of my planning: https://www.dropbox.com/s/bheunvtr886gp ... v3_eng.png I ordered most of the parts and will update you with some pictures soon.

bullen
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Re: power supply options for multiple PIs

Sun Mar 29, 2015 7:11 pm

Isn't this solution simpler?

Imagex4
+
Image
+
Image
=12$
Last edited by bullen on Tue Mar 31, 2015 12:30 pm, edited 1 time in total.
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kusti8
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Re: power supply options for multiple PIs

Sun Mar 29, 2015 7:27 pm

1) you're replying to a topic that has been dead for about 6 months.

2) you could do that, but:
A) you're going to need a pay with more than 2.5 A to power 5 pis. To be safe use something like 5-7 A.
B) i doubt a quality 2.5 A pay costs less than $10 last time I checked.
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bullen
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Re: power supply options for multiple PIs

Sun Mar 29, 2015 9:36 pm

Actually I paid 12$ for everything including shipping. That's Chinese deflation for you!

RPi 2 draws <500mA at full speed (all cores 100%).

So 2.5A is ok for 4x RPi 2.
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bitdivine
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Re: power supply options for multiple PIs

Mon Sep 28, 2015 10:58 am

@bullen That does indeed look very clean. Can you post where you found the parts or the names of the parts? Knowing their names is most of the battle when it comes to searching for parts!

Regards, Bit.

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