MarkJ62
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Location: Sydney, Australia
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PiFan - Fan on a case mod

Fri Feb 21, 2014 10:53 pm

I've tacked a fan on one of my Pi's and thought I would share it. The full details can be found on my blog markjatboinc

Here are a couple of pics
Image

Image

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cause4concern
Posts: 27
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Location: EU

Re: PiFan - Fan on a case mod

Sat Feb 22, 2014 3:07 am

No offense but why would one want to make a quiet thing noisy when it's unnecessary?

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rpdom
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Location: Chelmsford, Essex, UK

Re: PiFan - Fan on a case mod

Sat Feb 22, 2014 5:44 am

cause4concern wrote:No offense but why would one want to make a quiet thing noisy when it's unnecessary?
To cool down F3 to prevent it from "blowing" when trying to power a 290mA fan via the USB in addition to the power required by the Pi :lol:

MarkJ62
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Location: Sydney, Australia
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Re: PiFan - Fan on a case mod

Sat Feb 22, 2014 11:33 pm

cause4concern wrote:No offense but why would one want to make a quiet thing noisy when it's unnecessary?
Because its in a hot location, typically 30+ degrees.

With the top on the case only having a few small air holes they build up a fair bit of heat on their own when running at 100% load.

As for noise I don't notice it, the PC's in the room make much more noise.
Last edited by MarkJ62 on Sat Feb 22, 2014 11:44 pm, edited 1 time in total.

MarkJ62
Posts: 28
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Location: Sydney, Australia
Contact: Website

Re: PiFan - Fan on a case mod

Sat Feb 22, 2014 11:41 pm

rpdom wrote:
cause4concern wrote:No offense but why would one want to make a quiet thing noisy when it's unnecessary?
To cool down F3 to prevent it from "blowing" when trying to power a 290mA fan via the USB in addition to the power required by the Pi :lol:
290mA is well within the USB spec of 500mA.

I did consider running it directly off a USB power supply put that would mean longer cables and needing a dual USB power supply.

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rpdom
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Re: PiFan - Fan on a case mod

Sun Feb 23, 2014 8:34 am

MarkJ62 wrote:290mA is well within the USB spec of 500mA.
Yes, it is within the max current spec that a USB port might supply.

But the actual spec says that a USB port only needs to supply 100mA, which is what the Pi is designed to do.

Anyway, ambient temp of 30°C isn't very high. The important figure is how hot is the CPU/SoC running? If under 85°C then it is fine and needs no cooling. It is designed to work in enclosed spaces.

kyled2012
Posts: 17
Joined: Wed Feb 06, 2013 11:43 am

Re: PiFan - Fan on a case mod

Sun Feb 23, 2014 8:44 am

MarkJ62 wrote: 290mA is well within the USB spec of 500mA.
Just because a spec claims an Amperage does not mean every device will support that.
USB 2.0 Spec is 500mA and 3.0 is I believe 900mA, however the Rev1.0 Pi did not support current output that high, with a maximum output current of around 100mA across both ports. Rev 1.1 relieved this issue.
Doing your mod on a 1.0 board would have tripped the polyfuse on the USB ports.
Not arguing with you, just providing some background for anyone planning to do this mod!

On 2 of my Raspberry Pi projects I have switched to using 12V inputs and a 12V > 5V reg connected to the pi in order to use 12V fans for cooling. Obviously not suitable for your mod, but not bad for slightly bigger projects.

Nice work!
rpdom wrote:
MarkJ62 wrote:290mA is well within the USB spec of 500mA.
Yes, it is within the max current spec that a USB port might supply.

But the actual spec says that a USB port only needs to supply 100mA, which is what the Pi is designed to do.

Anyway, ambient temp of 30°C isn't very high. The important figure is how hot is the CPU/SoC running? If under 85°C then it is fine and needs no cooling. It is designed to work in enclosed spaces.
Rev 1.1 and later Pi B models will supply your input aperage less about 500mA. so for a 2A supply you could use roughly 1.5A off the USB ports.
Even if it doesn't strictly need cooling doesn't mean it's useless to have cooling. I prefer my devices not to reach 80°C+ temps, and in keeping the temps low you actually can extend the lifetime of some components.

Edit: I may present a slight bias as my main work with Pi is automotive installations, which can involve high temperatures, even under minimal load.

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rpdom
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Re: PiFan - Fan on a case mod

Sun Feb 23, 2014 8:56 am

kyled2012 wrote:USB 2.0 Spec is 500mA and 3.0 is I believe 900mA, however the Rev1.0 Pi did not support current output that high, with a maximum output current of around 100mA across both ports. Rev 1.1 relieved this issue.
Doing your mod on a 1.0 board would have tripped the polyfuse on the USB ports.
Not arguing with you, just providing some background for anyone planning to do this mod!

Rev 1.1 and later Pi models will supply your input aperage less about 500mA. so for a 2A supply you could use roughly 1.5A off the USB ports
Sorry, but that is totally wrong.

Unless you are supplying power via the GPIO pins or back-powering via USB, and therefore bypassing the input polyfuse F3, you will "blow" that polyfuse if you try to take more than about 250mA total from the USB ports.

The F1 and F2 fuses were removed because they dropped a tenth of a volt or so and meant the USB devices didn't get the 4.75 to 5.25V they required. Not because of the current limits.
rpdom wrote:Anyway, ambient temp of 30°C isn't very high. The important figure is how hot is the CPU/SoC running? If under 85°C then it is fine and needs no cooling. It is designed to work in enclosed spaces.
.
Even if it doesn't strictly need cooling doesn't mean it's useless to have cooling. I prefer my devices not to reach 80°C+ temps, and in keeping the temps low you actually can extend the lifetime of some components.
So your Pi will last 30 years, while mine will only last 28? Oh noes! :lol:

The default shutdown temp for some of the CPUs in my PCs is 120°C. 85°C is "slightly warm" for them.

kyled2012
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Re: PiFan - Fan on a case mod

Mon Feb 24, 2014 2:10 pm

rpdom wrote: Sorry, but that is totally wrong.

Unless you are supplying power via the GPIO pins or back-powering via USB, and therefore bypassing the input polyfuse F3, you will "blow" that polyfuse if you try to take more than about 250mA total from the USB ports.
You are correct, the F3 input polyfuse does support a peak of around 1100mA but will cause significant voltage drops. I was using figures of a modified unit with a higher level input fuse.
The F1 and F2 fuses were removed because they dropped a tenth of a volt or so and meant the USB devices didn't get the 4.75 to 5.25V they required. Not because of the current limits.
If you read my post, you would see I did not suggest that current was the reason for the polyfuse removal, I simply noted their removal and the removal of the 140mA limit. You clearly misinterpreted.
rpdom wrote: So your Pi will last 30 years, while mine will only last 28? Oh noes! :lol:

The default shutdown temp for some of the CPUs in my PCs is 120°C. 85°C is "slightly warm" for them.
Sarcasm aside, the lifetime of the components was only an additional pro of proper cooling.
While those kind of temps may be fine for your home PC, installations in confined spaces, or in spaces with high ambient temperatures (my installations tend to be both) are greatly assisted by a cooling system generating more airflow.

badrobot
Posts: 15
Joined: Tue Aug 06, 2013 4:33 pm

Re: PiFan - Fan on a case mod

Sat Mar 01, 2014 9:17 pm

cause4concern wrote:No offense but why would one want to make a quiet thing noisy when it's unnecessary?
That fan looks power hungry. I got the same but the fans came with a USB plug. It used to be a laptop cooler I got for $4.99 (on sale). I just tore it apart. It looks cool too (actually looks like block of ice). :)






Here's a bigger shot: https://mir6vw.dm1.livefilestore.com/y2 ... jpg?psid=1
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