PC cooling fans ...

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Rick Hughes

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Oct 27, 2008, 5:33:03 PM10/27/08
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Majority of these are low voltage DC units .... anybody know what type of
motors they are ?

I assume they are brushless units, are they switched commutator design?,
permanent magnet ?

Harry Bloomfield

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Oct 27, 2008, 5:39:36 PM10/27/08
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Rick Hughes presented the following explanation :

All the modern ones seem to be brushless types. Some have an extra
terminals which set their speed of rotation and provide feedback of
speed, but I'm not clear on just how this latter works.

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Kevin

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Oct 27, 2008, 5:54:35 PM10/27/08
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all the ones I have pulled apart are brushless with a static set of
windings and a rotating permanent magnet

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Kevin R
Reply address works

Bob Eager

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Oct 27, 2008, 5:59:07 PM10/27/08
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On Mon, 27 Oct 2008 21:39:36 UTC, Harry Bloomfield
<harry...@NOSPAM.tiscali.co.uk> wrote:

> Rick Hughes presented the following explanation :
> > Majority of these are low voltage DC units .... anybody know what type of
> > motors they are ?
> >
> > I assume they are brushless units, are they switched commutator design?,
> > permanent magnet ?
>
> All the modern ones seem to be brushless types. Some have an extra
> terminals which set their speed of rotation and provide feedback of
> speed, but I'm not clear on just how this latter works.

The three pin ones use two pins for power and common, and the third for
a rotation sensor that provides pulses.

The speed is controlled by pulse width modulation of the power feed.

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Michael Chare

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Oct 27, 2008, 7:39:59 PM10/27/08
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"Rick Hughes" <rick_...@btconnect.com> wrote in message
news:1_KdnYl0xtANrpvU...@bt.com...

See http://www.quietpc.com/gb-en-gbp/products

--
Michael Chare

Rod

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Oct 28, 2008, 5:42:49 AM10/28/08
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Description and photos of such a motor being disassembled.

<http://www.phys.unsw.edu.au/hsc/hsc/electric_motors6.html>

--
Rod

Hypothyroidism is a seriously debilitating condition with an insidious
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Although common it frequently goes undiagnosed.
<www.thyromind.info> <www.thyroiduk.org> <www.altsupportthyroid.org>

meow...@care2.com

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Oct 28, 2008, 10:13:26 AM10/28/08
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electronic commutation iirc


NT

Osprey

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Oct 28, 2008, 12:59:57 PM10/28/08
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OK ... seems consensus is t hat they are permanent magnet ... great so
far.

A few weeks back I detailed a project where I need to put air through
some pipes, don't need high pressure, or high flow .... anybody know
if I fitted a 4" ver of these fans into a box, if they would be able
to supply piped air 'out of the box' .... there could be for example
2 x 1'5" diam outlets.
If it makes sense I'm trying to make one of these items ...
http://home.earthlink.net/~toddclagett/NovaTech/drysuitdryer.htm

After initial idea I went to look at radial fans, and bathroom extract
duct fans ... all too expensive for this job.

There is a commercial product that uses a PC fan built into a coat
hanger, hence my thinking that PC fans may be an answer.
I'm guessing though t hat they are happy blowing into effectively a
big bag ... but won't be so happy if I try to pipe the air (back
pressure?)

Kevin

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Oct 28, 2008, 2:42:59 PM10/28/08
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I dont think 1 pc fan would work but try http://www.dorothybradbury.co.uk/
for a range of fans

andrew

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Oct 28, 2008, 2:49:11 PM10/28/08
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Osprey wrote:

> There is a commercial product that uses a PC fan built into a coat
> hanger, hence my thinking that PC fans may be an answer.
> I'm guessing though t hat they are happy blowing into effectively a
> big bag ... but won't be so happy if I try to pipe the air (back
> pressure?)


I think you'd be better off with a laptop centrifugal fan (or 2) with
possibly a pulse width modulated 12V supply.

I use ones that Dorothy on uk computers home built sells for about 7 quid,
for blowing small cookstoves. The small one NMB_MAT draws 0.38 A max.

AJH

meow...@care2.com

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Oct 29, 2008, 11:31:34 AM10/29/08
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On Oct 28, 4:59 pm, Osprey <rick_hug...@btconnect.com> wrote:
> On 27 Oct, 21:33, "Rick Hughes" <rick_hug...@btconnect.com> wrote:
>
> > Majority of these are low voltage DC units .... anybody know what type of
> > motors they are ?
>
> > I assume they are brushless units, are they switched commutator design?,
> > permanent magnet ?
>
> OK ... seems consensus is t hat they are permanent magnet ... great so
> far.
>
> A few weeks back I detailed a project where I need to put air through
> some pipes, don't need high pressure, or high flow  .... anybody know
> if I fitted a 4" ver of these fans into a box, if they would be able
> to supply piped air 'out of the box'  .... there could be for example
> 2 x 1'5" diam outlets.
> If it makes sense I'm trying to make one of these items ...http://home.earthlink.net/~toddclagett/NovaTech/drysuitdryer.htm

>
> After initial idea I went to look at radial fans, and bathroom extract
> duct fans ... all too expensive for this job.
>
> There is a commercial product that uses a PC fan built into a coat
> hanger, hence my thinking that PC fans may be an answer.
> I'm guessing though t hat they are happy blowing into effectively a
> big bag ... but won't be so happy if I try to pipe the air (back
> pressure?)

If youre not looking for fast drying, a standard pc fan would be fine.
I dont know why you'd want to pipe it anywhere.


NT

Osprey

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Oct 29, 2008, 11:41:08 AM10/29/08
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I looked at the site ... these appear (to me) to be radial fans, not
centrifugal ? ..... i.e air flows is on axis through the fan.
With centrifugal air comes in on axis and is pressurised off at a
tangent at 90 degress (i.e blower design)

Message has been deleted

Rick Hughes

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Oct 30, 2008, 11:58:27 AM10/30/08
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<meow...@care2.com> wrote in message

> 2 x 1'5" diam outlets.
> If it makes sense I'm trying to make one of these items
> ...http://home.earthlink.net/~toddclagett/NovaTech/drysuitdryer.htm
>
> After initial idea I went to look at radial fans, and bathroom extract
> duct fans ... all too expensive for this job.

If youre not looking for fast drying, a standard pc fan would be fine.
I dont know why you'd want to pipe it anywhere.


NT


If you look at the link I gave ... the guy had a neat idea that he built a
frame , suit goes over the frame ,,, and air is blown into frame, it comes
out at ends .. and thus air is pushed into far 'corners' of suit ..... low
volume low pressure air, but drys suit in a couple of hours instead of days.

meow...@care2.com

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Oct 30, 2008, 12:03:18 PM10/30/08
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On Oct 30, 3:58 pm, "Rick Hughes" <rick_hug...@btconnect.com> wrote:
> <meow2...@care2.com> wrote in message

Yes I did look. My point, perhaps not well enough explained, is that
you get better performance using a fan on a baffle than piping it
about. The suit acts as its own ducting.


NT

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