Pi 3 B+: Needs Cooling?

Hello Bernd!
Friday January 11 2019 10:36, you wrote to All:
Change case and fan/s to a 12 or 14" variable mode one or two placed left and right or front and back.
Have three in my primary system and very rarely hear any thing.
Vince
Reply to
Vince Coen
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Hi,
if I search for cases for my RasPi 3 B+, I found the most cases has
additional heat spreader and fan. It is fact that a RasPi 3 B+ needs
additional cooling? (Fans are noisy ...)
Bernd
Reply to
Bernd
Depends on what you're doing with it. IME if you're playing video that'll push the temperature up, but everything else is fine.
Reply to
Roger Bell_West
Thx,
I'll cut the fan cable ;-)
Bernd
Reply to
Bernd
Not sure. Even idling several parts in mine got too hot to touch. I have bought a set of stick-on heatsinks and feel better now. A fan seems overkill, but a closed case may keep the warmth in.
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Reply to
Axel Berger
Cheap passive cooling (and an open/half open case) is good enough for 99%
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Reply to
A. Dumas
Or, for a case with a ventilation hole on top, disable the fan and fit a cardboard tube of at least the diameter of the vent hole to use the chimney effect for cooling. Not sure what size the tube would need to be - 50cm @ 50mm diam - but its something you can try at zero cost and with almost no preparation.
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Martin    | martin at 
Gregorie  | gregorie dot org
Reply to
Martin Gregorie
And never forget that ventilation at the top is useless without corresponding openings at the bottom and vice versa. I say this this, because I've seen that kind of silliness. Often there are openings at the bottom, where you can't see them, but a nice, shiny, and totally closed top.
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Reply to
Axel Berger
Hi-speed fans are noisy, low-speed ones aren't.
Fit a 40mm 5V fan (eg CPC MF67761, lots of blade area, quoted 27 dBA) that'll be pretty quiet connected directly to 5V.
Want quieter feed it via transistor from a GPIO producing a PWM signal under software control. Can arrange for it to only run when required and only as fast as needs be. Note if going from stopped to moving it might need a brief full whack burst to get it going. Donno how easy getting the CPU temp is (or isn't).
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Cheers 
Dave.
Reply to
Dave Liquorice
Not always. I have a tiny fan on my 3B+ and it is just audible when run off 5V, but inaudible at 3V3. The lower voltage still gives sufficient airflow to prevent thermal throttling on any workload I give it, where as in a case without a fan, it quickly runs away.
---druck
Reply to
druck
Fair comment - and equally applicable to fans as well as chimneys.
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Martin    | martin at 
Gregorie  | gregorie dot org
Reply to
Martin Gregorie
Just how big is your Raspberry Pi case?
---druck
Reply to
druck
On Fri, 11 Jan 2019 21:39:28 +1300, snipped-for-privacy@f1.n50.z2.binkp.net (Vince Coen) declaimed the following:
Pardon? A 12 INCH fan for a board that is barely 3 inches on the long side?
I, for one, can't spare a microwave oven for a credit card computer.
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	Wulfraed                 Dennis Lee Bieber         AF6VN 
	wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/
Reply to
Dennis Lee Bieber
Am 11.01.19 um 10:36 schrieb Bernd:
Thx, for your comments. Meanwhile I have found how to measure the temp from the RasPi. This and the tip to use a 5V fan but connect to 3.3V does the trick.
Thx for the ideas!
Bernd
Reply to
Bernd
Bernd wrote, on 12-01-2019 09:20:
Readable output, not directly useful in scripts: $ vcgencmd measure_temp temp=46.2'C
Value in millidegrees: $ cat /sys/class/thermal/thermal_zone0/temp 47236
Value in degrees rounded down, so 47.9 becomes 47: $ echo $(($(cat /sys/class/thermal/thermal_zone0/temp)/1000)) 47
Value in degrees with one decimal, using bc: $ echo "scale=1;$(cat /sys/class/thermal/thermal_zone0/temp)/1000" | bc 46.5
The same thing without bc: $ vcgencmd measure_temp | cut -d= -f2 | cut -d' -f1 46.2
(The decimal separator is not localised for any of these.)
Reply to
A. Dumas
On a sunny day (Sat, 12 Jan 2019 10:13:49 +0100) it happened "A. Dumas" wrote in :
Degrees Kelvin?
Reply to
Jan Panteltje
Here's something new for you to learn: the unit symbol is K, the unit name is kelvin, the person is Kelvin.
Reply to
A. Dumas
[]
Celcius, with a power of 10 multiplier.
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Cheers, 
David 
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Reply to
David Taylor
Indeed. :-)
Reply to
Rob Morley
On a sunny day (Sat, 12 Jan 2019 11:21:13 +0000) it happened David Taylor wrote in :
Wrong
Just add 273.15 But can he do that ;-)
Reply to
Jan Panteltje

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