maxtothemax
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Re: Cooling/ventilation requirements for R-Pi Model B

Fri Dec 09, 2011 10:52 pm

I\'m planning to build an enclosure for the Raspberry Pi model B. What are the cooling and ventilation requirements? How much clearance is needed? Do I need vents and fans? Heatsinks? Does it depend on how much external hardware is drawing power from the device?

To give an idea of the scale of the enclosure, my plan is to rip out the numpad on my Model M keyboard and fit the enclosure into the hole where it used to be, to make one of those old-school keyboard/PC combos. The enclosure will likely be made of some combination of wood, PLA, and/or acryllic, so it\'s not going to have particularly good thermal dispersion properties.

obarthelemy
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Re: Cooling/ventilation requirements for R-Pi Model B

Fri Dec 09, 2011 10:56 pm

No ventilation nor cooling required, the thing uses 1.5W.
As for clearances and connectors, we\'re still waiting for details. Highest point is dual USB (stacked), t plus board and then SD card under it.

maxtothemax
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Re: Cooling/ventilation requirements for R-Pi Model B

Fri Dec 09, 2011 10:59 pm

What if I\'m powering, say, an external hard drive off it? Would the extra electricity drive up heat output significantly?

ProDigit
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Re: Cooling/ventilation requirements for R-Pi Model B

Fri Dec 09, 2011 11:07 pm

I doubt it, though I would advise against using heat insulating materials like wood, or wool; especially when they are touching the chip; and no dipping the device in liquid plastic to coat it with a layer that just fits like a jacket!
If the housing is large enough (eg more than 2mm away from the chip) there\'s no real fear for overheating!

maxtothemax
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Re: Cooling/ventilation requirements for R-Pi Model B

Fri Dec 09, 2011 11:12 pm

The enclosure is probably going to have quite a lot more room than 2mm of clearance, just so I can fit in a USB hub, toggle switch, \"blue cube\" for the keyboard, etc.

I\'m not too worried, honestly. If it fries, I\'m only down $35.

Thanks for the advice, everyone!

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johnbeetem
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Re: Cooling/ventilation requirements for R-Pi Model B

Fri Dec 09, 2011 11:55 pm

[quote]Quote from maxtothemax on December 9, 2011, 22:59
What if I\'m powering, say, an external hard drive off it? Would the extra electricity drive up heat output significantly? [/quote]

If you\'re powering an external hard drive through a RasPi USB port, the +5V current is going through the RasPi PC board from the power input (micro USB). There\'s not much voltage drop across the board, though I\'d worry about the voltage drop across the micro USB cable. You also might trip the RasPi\'s resettable fuse... don\'t know what the rating is. So you\'re probably better off providing a more direct power source to your hard drive.

Regarding the RasPi itself, even if the Model B board is only drawing 500 mA by itself, at 5V that\'s still 2.5W. I hear that the SoC gets pretty warm when it\'s working hard, e.g., lots of graphics and/or video. It\'s a small package for that much power. As long as there\'s some air flow 2.5W is not a problem, but if the case is sealed I\'d worry about it overheating. I tend to be overly cautious about electronics overheating because it can really shorten its lifetime. I\'m probably the only Beagler to put a heat sink on his BeagleBoard\'s SoC.

maxtothemax
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Re: Cooling/ventilation requirements for R-Pi Model B

Sat Dec 10, 2011 12:17 am

Yeah, that was a lapse of memory on my part-- most external HDDs have their own power supplies.

The keyboard itself draws half a watt (which is kind of ludicrous if you think about it.) Now that I think about it, everything else I might need to connect (external hard drive, printers, and sometimes a monitor) will have its own power supply.

As luck would have it, the Model M keyboard has an unused speaker grille right underneath the numpad. I can stick a small fan there.

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johnbeetem
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Re: Cooling/ventilation requirements for R-Pi Model B

Sat Dec 10, 2011 8:50 pm

Probably won\'t need a fan. Just some slots for passive air flow so heat doesn\'t accumulate around the SoC.

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Gert van Loo
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Re: Cooling/ventilation requirements for R-Pi Model B

Sat Dec 10, 2011 11:06 pm

The PCB alone will act as a heat spreader. We tried to heat a BCM2835 on a board in our lab.
We could not get it above 45C. But that was a board without the power supplies.
So unless you wrap it up in extreme layers of insulation I would not worry about it.

gladoscc
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Re: Cooling/ventilation requirements for R-Pi Model B

Sun Dec 11, 2011 12:31 am

Agreed. No fans needed. If you put it inside the speaker grille then it will be alright. (correct direction, of course)

ProDigit
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Re: Cooling/ventilation requirements for R-Pi Model B

Thu Mar 29, 2012 7:55 am

make the housing out of metal and you won't even need air ducts.

mole125
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Re: Cooling/ventilation requirements for R-Pi Model B

Thu Mar 29, 2012 8:08 am

I don't think it even needs to be metal - mobile phones don't tend to have air ducts/airflow and the cheaper ones have very cheap plastic cases.

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