zeeteex
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Raspberry Pi Cooling system? :D

Sat Jun 16, 2012 3:09 pm

Before I receive a barrage of messages telling me that it isn't necessary, it doesn't get hot enough blah blah... I am doing this because i want to! I want to try and connect a 5V 25mm fan to the GPIO headers and incorporate this into an acrylic/card case.

So, I just want to know your opinions on it and if you think it is even possible.

I plan to buy this 25mm 5V fan http://uk.rs-online.com/web/p/axial-fans/5440481/

And mount it just above the processor on a piece of acrylic with a hole in to fit the fan size. How can i connect it to the GPIO, or cant i? I know the GPIO is 3.3V but will that just mean it cannot spin as fast?

I just want to see if this will work because if it does, it would look very cool, just like a desktop pc with heatsink and all
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Re: Raspberry Pi Cooling system? :D

Sat Jun 16, 2012 3:27 pm

zeeteex wrote:Before I receive a barrage of messages telling me that it isn't necessary, it doesn't get hot enough blah blah... I am doing this because i want to! I want to try and connect a 5V 25mm fan to the GPIO headers and incorporate this into an acrylic/card case.

So, I just want to know your opinions on it and if you think it is even possible.

I plan to buy this 25mm 5V fan http://uk.rs-online.com/web/p/axial-fans/5440481/

And mount it just above the processor on a piece of acrylic with a hole in to fit the fan size. How can i connect it to the GPIO, or cant i? I know the GPIO is 3.3V but will that just mean it cannot spin as fast?

I just want to see if this will work because if it does, it would look very cool, just like a desktop pc with heatsink and all
You don't seem to realise that the GPIO port also carries a +5v supply... And the fact that you're asking how to connect it really suggests to me that you really shouldn't bother trying...

But if you do want to, then you'll need to get the GPIO pinout, terminate the fan leads in female connectors to push over the 2 relevant pins on the GPIO and off you go ...

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Re: Raspberry Pi Cooling system? :D

Sat Jun 16, 2012 3:54 pm

You see i was sure it did have 5V pins but the more i looked into it the less i was sure. Yeah i thought that would be the way to do it, just wanted clarification, so thankyou!!!
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Re: Raspberry Pi Cooling system? :D

Sat Jun 16, 2012 4:03 pm

What's the current draw of the fan at 5v? I see from the datasheet it's 110 mA.
Will the Pi cope with that? (Just asking the question - I don't know the answer).
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Re: Raspberry Pi Cooling system? :D

Sat Jun 16, 2012 4:07 pm

alexeames wrote:What's the current draw of the fan at 5v?
110mA, thats fine isnt it? I dont have massively populated usb ports either so...
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Re: Raspberry Pi Cooling system? :D

Sat Jun 16, 2012 4:08 pm

zeeteex wrote:
alexeames wrote:What's the current draw of the fan at 5v?
110mA, thats fine isnt it? I dont have massively populated usb ports either so...
You'd think so, but it's worth checking out the spec of the GPIO before you hook it up. :D
Don't want to see the magic white smoke come out. :mrgreen:
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Re: Raspberry Pi Cooling system? :D

Sat Jun 16, 2012 4:17 pm

alexeames wrote: You'd think so, but it's worth checking out the spec of the GPIO before you hook it up. :D
Don't want to see the magic white smoke come out. :mrgreen:
Haha fair enough... According to this post... http://www.raspberrypi.org/phpBB3/viewt ... raw#p91130 It is probably too high, but according to that, the GPIO headers only give out around 50mA.... It cant draw more than that can it?
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Re: Raspberry Pi Cooling system? :D

Sat Jun 16, 2012 4:41 pm

Current limit and current drawn are two different things

If the gpio is limited to 50mA then the fan will simply run slow and constantly hit the limiter how ever if the gpio doesn't have a limiter then the fan will over draw current and may cause damage to the PCB as the tracks feeding the gpio are normally only big enough to carry the desired current no one makes tracks for more currant than the circuitry can handle
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Re: Raspberry Pi Cooling system? :D

Sat Jun 16, 2012 4:45 pm

If you supply 5v to the fan. It will try to draw its full current. If the device can't provide it, something will have to give. The question is what? I don't know enough about the GPIO circuit to answer that. Someone else will be along in a minute, no doubt. :D
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Re: Raspberry Pi Cooling system? :D

Sat Jun 16, 2012 4:48 pm

thexman wrote:Current limit and current drawn are two different things

If the gpio is limited to 50mA then the fan will simply run slow and constantly hit the limiter how ever if the gpio doesn't have a limiter then the fan will over draw current and may cause damage to the PCB as the tracks feeding the gpio are normally only big enough to carry the desired current no one makes tracks for more currant than the circuitry can handle
Thanks for that :) that is what i had expected, i ordered the parts... Should recieve them on Monday, will report back with how it goes once its all done! Also on the specsheet it says the fan runs at 13000 rpm at full power, which is a lot of speed for such a small fan, desktop fans usually run happily at about 4000-5000rpm... so If there is only half the expected power draw will there be half the run speed? All this is based purely on assumptions and i have only just left school so have little/no experience with this! But i love the pi and what it can do!
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Re: Raspberry Pi Cooling system? :D

Sat Jun 16, 2012 7:32 pm

Several people have reported that they have powered their RPi through the 5v GPIO pin. If they can get 500mA in through this pin, you will easily be able to get 110mA out through this pin.

However, this is a really pointless thing to do. You already seem to understand that the RPi doesn't need any cooling. But you also lose the major advantage of using a SoC, the fact that it is a silent computer. Mounting a fan on acrylic may cause a lot of noise.

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Re: Raspberry Pi Cooling system? :D

Sat Jun 16, 2012 10:47 pm

bredman wrote:However, this is a really pointless thing to do. You already seem to understand that the RPi doesn't need any cooling. But you also lose the major advantage of using a SoC, the fact that it is a silent computer. Mounting a fan on acrylic may cause a lot of noise.
True, i definitely see your point, but this research alone has already helped me to understand hardware that i previously had no idea about, there are loads of things people are doing with their pi's that other people may deem completely pointless, but each person's interests may lead them to want to try new and different things, just for the sake of learning and widening their range of thoughts!

Just a point :D
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Re: Raspberry Pi Cooling system? :D

Sun Jun 17, 2012 6:11 am

Use a larger (more amperage) than necessary PSU and take your power from it before the RasPi. You should be able to find a way to do it at your local electronics parts house, "Y" the cable. Another option, power from a port on the USB powered hub if you plan on using one. And another option power it through a relay from the GPIO, again stealing the actual power from the PSU. Use a temperature sensor to control when it runs. Learn a little programming for the GPIO while you are at it.

Too many people look at the problems and ignore the options.

So the RasPi realy does not need cooling. Maybe not under normal use, but what about a automobile installation under the dash. Or abishur is using one near a heat source. A controller cabinet outside in the sun. No you cannot just say it will never be necessary. Of course JamesH disagrees with me. My opinion Cooler is always better. My HDD's will run fine in my server at at 125 degrees, but they will run just as good at their current 94 degrees and they will last longer. You want a fan plan it out and "Get'er Done"
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Re: Raspberry Pi Cooling system? :D

Sun Jun 17, 2012 8:35 am

I don't personally disagree with you, but all the Broadcom environmental testing (in ovens at higher tempos that almost anyone will encounter) does. These chips undergo a colossal amount of testing before they are released to the public - hot, cold, in between, to determine lifetimes, failures etc . If a chip fails in this testing we spend a huge amount of money finding out why and fixing it. There are millions of chips out there that are in equipment without fans. That's their whole point, the reason they were designed - to be capable of running at high performance without active cooling.
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Re: Raspberry Pi Cooling system? :D

Sun Jun 17, 2012 3:37 pm

I understand that the SoC was extensively environmentally tested, but was the same done for the currently shipping R-Pi circuit board? The USB/Eth chip, the polyfuses, and other things might also contribute their own reliability issues.

One thing to be aware of: fans can add a significant amount of electrical noise to a power supply. It might not matter- and then again, it might, especially if your onboard power supply level is marginal to begin with.

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Re: Raspberry Pi Cooling system? :D

Mon Jun 18, 2012 8:10 am

My RPi is OK as it is but just a thought, would a wind tunnel work lol? You could always make one of your own on a miniature scale. You might like to fasten the RPi down securely first though.... ;) ;) :lol:

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Raspberry Pi Cooling system? Successful!

Mon Jun 18, 2012 11:53 am

Thank you all for your responses. Today the fan arrived, along with a 12mm heatsink I ordered and some thermal tape. Placed the heatsink on easy with the tape, and wired up the + wire of the fan, to the 5V GPIO pin, and the - wire to the ground pin. Plugged in the pi and bingo, fan starts up and works like an absolute charm.

Havent yet built/found the case that i can mount it to, but if you want to have a look, here is the picture album.

https://plus.google.com/photos/11123183 ... 1860267489

Feel free to let me know what you think!

Jake
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Re: Raspberry Pi Cooling system? :D

Mon Jun 18, 2012 12:51 pm

zeeteex wrote:You see i was sure it did have 5V pins but the more i looked into it the less i was sure.
http://elinux.org/RPi_Low-level_peripherals (which also has info on max current draws)

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Re: Raspberry Pi Cooling system? Successful!

Mon Jun 18, 2012 12:56 pm

zeeteex wrote:https://plus.google.com/photos/11123183 ... 1860267489
Feel free to let me know what you think!
You really ought to be using proper female headers to connect to the GPIO connector :!:
With your current "loose wires" approach it's far too easy for e.g. the 5V to touch one of the other connectors, which would "burn out" that GPIO pin inside the CPU.

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Re: Raspberry Pi Cooling system? Successful!

Mon Jun 18, 2012 1:27 pm

zeeteex wrote:Thank you all for your responses. Today the fan arrived, along with a 12mm heatsink I ordered and some thermal tape. Placed the heatsink on easy with the tape, and wired up the + wire of the fan, to the 5V GPIO pin, and the - wire to the ground pin. Plugged in the pi and bingo, fan starts up and works like an absolute charm.

Havent yet built/found the case that i can mount it to, but if you want to have a look, here is the picture album.

https://plus.google.com/photos/11123183 ... 1860267489

Feel free to let me know what you think!

Jake
I think you're bonkers and I think the Broadcom people are right, don't bother with a fan &| heatsinks...

However, in the vein of "if ye canny beat them, join them", I have gone one step further and constructed the ultimate fan for the Pi. I have used an LM35 temperature sensor (identified as the little chip with the blue, green and red wires connected to it on-top of the SoC/Memory unit) and connected this back to an ATmega chip and this then talks to the Pi via the serial port which then talks to a motor speed controller and to the motorised fan via the Pi's own PWM output. The breadboad I'm using is purely a prototype and is all patent-pending, (as well as being a quickly cobbled together mess!) so is under wraps for now.

However it works well, as you can see in the 2nd photo when I overclockd the Pi to 2GHz and run hello_triangle - which was nothing but a blur on the screen, the fan automatically sped up, keeping the Pi nice and cool.

I'll be selling this as a fully functioning and tested kit later on, but meanwhile, you can register interest by emailling me and making a donation to my bank account - minimum of £1023.00 though.

Enjoy!

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Re: Raspberry Pi Cooling system? :D

Mon Jun 18, 2012 1:37 pm

I think you might have started something here zeeteex :lol:
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Re: Raspberry Pi Cooling system? Successful!

Mon Jun 18, 2012 1:44 pm

[email protected] wrote: I think you're bonkers and I think the Broadcom people are right, don't bother with a fan &| heatsinks...
Oh come on. I did this for the sole purpose of learning how the GPIO pins work, picking up some general knowledge, and because i wanted to play an (admittedly tiny) role in finding out the different things people can do with the pi. So please stop saying that things that people come up with are useless, because i have just left school, and have a rather limited outlook on how things work, and so, i am trying to learn. Is that not the original purpose for the raspi? To teach? And so, thats what i have done :) I cant create complex electrical circuits with transistors and relays yet, but it will eventually all add up. We all start somewhere right? Show a little sympathy for those who are complete novices and have a desire to learn.

On the other hand, that lego fan is very cool!
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Re: Raspberry Pi Cooling system? :D

Mon Jun 18, 2012 2:04 pm

Also I have just ordered a few female connectors to use rather than the bare wires. I think i will make a lego case for now. :)
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Re: Raspberry Pi Cooling system? :D

Mon Jun 18, 2012 2:05 pm

jbeale wrote:...One thing to be aware of: fans can add a significant amount of electrical noise to a power supply.....
+1 ... any fan circuit should be isolated from the GPIO's

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Re: Raspberry Pi Cooling system? Successful!

Mon Jun 18, 2012 2:12 pm

zeeteex wrote:
[email protected] wrote: I think you're bonkers and I think the Broadcom people are right, don't bother with a fan &| heatsinks...
Oh come on. I did this for the sole purpose of learning how the GPIO pins work, picking up some general knowledge, and because i wanted to play an (admittedly tiny) role in finding out the different things people can do with the pi. So please stop saying that things that people come up with are useless, because i have just left school, and have a rather limited outlook on how things work, and so, i am trying to learn. Is that not the original purpose for the raspi? To teach? And so, thats what i have done :) I cant create complex electrical circuits with transistors and relays yet, but it will eventually all add up. We all start somewhere right? Show a little sympathy for those who are complete novices and have a desire to learn.
Oh come on. I think you need to take everything in context - so just presenting this as a post without the rest of what I did is very misleading indeed. Maybe I missed a ;-) on the end of the line though. It's hard to fully get context and meaning in electronic messaging though, but it should have been pretty obvious that I was just taking the mickey.

Anyway, I said you were bonkers, not that your project was useless. MY project is useless and people probably think I'm bonkers for doing it, but it was good fun...

And that's what counts.
zeeteex wrote:On the other hand, that lego fan is very cool!
Yes indeed. And it really is being controlled by the Pi, and the Pi realy is reading the temperature sensor via an Arduino type device.

However back to your project. It's fine - but hooking wires up like that and one day you'll accdentally short the +5V pin to the +3.3v pin (they are next to each other!) and that will ruin your entire day.

Get some female to female connectors and some female to male and use those. Get a soldering iron and some basic tools and learn to use them. Heatshrink sleeving (which is what's on the LM35 sensor I used) is always good too. A little bit of ivestment now will serve you for a long time. My Weller temperature controlled soldering iron cost me a small arm and leg 35 years ago (and it was 2nd hand then), but it's still going strong...

Have fun, but not at the expense of the Pi!

-Gordon
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