My application needs a controlled heater fan situation, which means it 
should move a reasonable volume of air. I also need to control both 
speed and direction of fan.
Can anyone point me to information resource that preferably uses back 
emf for speed/direction sensing. Pref using 8051. Of course, have 
searched before asking.
Thanks,
Alistair.

Alistair George scrobe on the papyrus:

> My application needs a controlled heater fan situation, which means
> it should move a reasonable volume of air. I also need to control
> both speed and direction of fan.  Can anyone point me to information
> resource that preferably uses back emf for speed/direction sensing.
> Pref using 8051. Of course, have searched before asking.  Thanks,
> Alistair.

Brushless DC fans are generally not reversible. Internally they consist
of a three phase motor and a small driver circuit, usually comprising
three transistors forming an astable ring oscillator. Break one open
and have a look.

There's a good treatise on brushless fan speed control here:

 http://www.maxim-ic.com/appnotes.cfm/appnote_number/1784/

I built one recently using a MAX522 (DAC with an SPI interface), a
TL082 as a level translator and a TIP122. I'll let you have a schematic
it helps.

-- 
John B

John B wrote:
> Alistair George scrobe on the papyrus:
> 
>> My application needs a controlled heater fan situation, which means
>> it should move a reasonable volume of air. I also need to control
>> both speed and direction of fan.  Can anyone point me to information
>> resource that preferably uses back emf for speed/direction sensing.
>> Pref using 8051. Of course, have searched before asking.  Thanks,
>> Alistair.
> 
> Brushless DC fans are generally not reversible. Internally they consist
> of a three phase motor and a small driver circuit, usually comprising
> three transistors forming an astable ring oscillator. Break one open
> and have a look.
> 
> There's a good treatise on brushless fan speed control here:
> 
>  http://www.maxim-ic.com/appnotes.cfm/appnote_number/1784/
> 
> I built one recently using a MAX522 (DAC with an SPI interface), a
> TL082 as a level translator and a TIP122. I'll let you have a schematic
> it helps.
> 
Thanks John.
http://www.intel.com/design/mcs51/applnots/27062201.pdf
Reversible and more. I am pleased to have found this article, as it 
gives me a good insight as to hardware required. However, I need to 
sense temperature too and may use my trusty AT89C2051 with the a/d port.

Since you have already been down that track, can you recommend any 
company that supplies reliable, low cost dc motors suitable for the job, 
pref china or similar low cost area.?
Alistair.

Alistair George scrobe on the papyrus:

.
.
> Thanks John.
> http://www.intel.com/design/mcs51/applnots/27062201.pdf
> Reversible and more. I am pleased to have found this article, as it
> gives me a good insight as to hardware required. However, I need to
> sense temperature too and may use my trusty AT89C2051 with the a/d
> port.
> 
> Since you have already been down that track, can you recommend any
> company that supplies reliable, low cost dc motors suitable for the
> job, pref china or similar low cost area.?  Alistair.

Hi Alistair,

Yes reversible but you need to get access to the motor windings. That's
not generally possible in a COTS fan with a brushless DC motor, unless
you can find one with a removable impellor. The driver is generally
built into the fan hub and only has three wires, +, - and tacho output.

In my application the fan I used didn't need to be reversed as it was
in a small wind tunnel for testing RF mixer modules in a controlled
airflow. I just needed to provide a DC supply which was controllable
from 8V to 24V and used a standard brushless DC fan. Air velocity was
measured with a hot-wire transmitter and temperature with some NTC
thermistors. It all worked really well.

Sorry I'm not an 8051 man as I have used AVR's for many years now and
can't comment on the ADC. I would recommend that you look at the PWM
features of the ATmega32 for speed control and its 10-bit ADC is good
too.

-- 
John B

Alistair George wrote:
> My application needs a controlled heater fan situation, which means it
> should move a reasonable volume of air. I also need to control both
> speed and direction of fan.
> Can anyone point me to information resource that preferably uses back
> emf for speed/direction sensing. Pref using 8051. Of course, have
> searched before asking.
> Thanks,
> Alistair.

Hi Alistair,

you really want to have a look at the Infineon devices, this could be
the C868, C504 or similar.  They also have very good application Notes

They have all dynamic links (almost impossible to link to anything).
Hope it works:
http://www.infineon.com/cgi-bin/ifx/portal/ep/channelView.do?channelId=-64450&channelPage=%2Fep%2Fchannel%2FproductO
verview.jsp&pageTypeId=17099

If not www.infineon.com/microcontrollers then XC800 family

An Schwob

An Schwob in the USA wrote:
> Alistair George wrote:
>> My application needs a controlled heater fan situation, which means it
>> should move a reasonable volume of air. I also need to control both
>> speed and direction of fan.
>> Can anyone point me to information resource that preferably uses back
>> emf for speed/direction sensing. Pref using 8051. Of course, have
>> searched before asking.
>> Thanks,
>> Alistair.
> 
> Hi Alistair,
> 
> you really want to have a look at the Infineon devices, this could be
> the C868, C504 or similar.  They also have very good application Notes
> 
> They have all dynamic links (almost impossible to link to anything).
> Hope it works:
>
http://www.infineon.com/cgi-bin/ifx/portal/ep/channelView.do?channelId=-64450&channelPage=%2Fep%2Fchannel%2FproductO
verview.jsp&pageTypeId=17099
> 
> If not www.infineon.com/microcontrollers then XC800 family
> 
> An Schwob
> 
Hi, I started off with the idea of using a DC brushless motor, but found 
that they are too expensive (at least I have not found any motors low 
cost/Chinese suitable for household fan).
An Schwob, the infineon solution looks really good, and appreciate your 
pointer. I will follow that up more. But I still have a problem with 
sourcing a cheap typical household heater fan, that can reverse as well 
as alter speed. So I guess it must be 3-phase motor, low power are 
common and cheap, so it seems that I need to get the info relating to 
motor type, and driver informations. From there I can work out logic 
methods needed for the application.
All tips appreciated.
Alistair.

On Thursday, in article <4...@news.orcon.net.nz>
     n...@xtra.co.nz "Alistair George" wrote:
>An Schwob in the USA wrote:
>> Alistair George wrote:
>>> My application needs a controlled heater fan situation, which means it
>>> should move a reasonable volume of air. I also need to control both
>>> speed and direction of fan.
>>> Can anyone point me to information resource that preferably uses back
>>> emf for speed/direction sensing. Pref using 8051. Of course, have
>>> searched before asking.
>>> Thanks,
>>> Alistair.
>> 
>> Hi Alistair,
>> 
>> you really want to have a look at the Infineon devices, this could be
>> the C868, C504 or similar.  They also have very good application Notes
>> 
...
>> If not www.infineon.com/microcontrollers then XC800 family
>> 
>> An Schwob
>> 
>Hi, I started off with the idea of using a DC brushless motor, but found 
>that they are too expensive (at least I have not found any motors low 
>cost/Chinese suitable for household fan).
>An Schwob, the infineon solution looks really good, and appreciate your 
>pointer. I will follow that up more. But I still have a problem with 
>sourcing a cheap typical household heater fan, that can reverse as well 
>as alter speed. So I guess it must be 3-phase motor, low power are 
>common and cheap, so it seems that I need to get the info relating to 
>motor type, and driver informations. From there I can work out logic 
>methods needed for the application.
>All tips appreciated.

I suggest you also do a search on the mechanical aspects of fans/pumps
and propellers, as to get a reversible fan requires special shaping of
the blades, some will hardly work at all in reverse direction. The blades
are shaped for air/fluid flow in one direction only. The efficiency in some
cases is very small in reverse direction.

You may end up with a different shape to what you were expecting.

-- 
Paul Carpenter          | p...@pcserviceselectronics.co.uk
<http://www.pcserviceselectronics.co.uk/>;    PC Services
<http://www.gnuh8.org.uk/>;              GNU H8 & mailing list info
<http://www.badweb.org.uk/>;             For those web sites you hate

[snip]
>
> I suggest you also do a search on the mechanical aspects of fans/pumps
> and propellers, as to get a reversible fan requires special shaping of
> the blades, some will hardly work at all in reverse direction. The blades
> are shaped for air/fluid flow in one direction only. The efficiency in 
> some
> cases is very small in reverse direction.
>
> You may end up with a different shape to what you were expecting.
>
A pair of fans pointing in opposite directions would be a lot simpler. Just 
power one at a time to get the direction that you want.
Peter 

Peter wrote:
> [snip]
>> I suggest you also do a search on the mechanical aspects of fans/pumps
>> and propellers, as to get a reversible fan requires special shaping of
>> the blades, some will hardly work at all in reverse direction. The blades
>> are shaped for air/fluid flow in one direction only. The efficiency in 
>> some
>> cases is very small in reverse direction.
>>
>> You may end up with a different shape to what you were expecting.
>>
> A pair of fans pointing in opposite directions would be a lot simpler. Just 
> power one at a time to get the direction that you want.
> Peter 
> 
> 
One of the reverse directions is not so important about fan throughput. 
Typically, the fan operates as per a household summer cooling fan eg fan 
blade diameter of 400-500mm, with variable speed, reverse.
 From what I have read so far, the Permanent Split Capacitor (PSC) motor 
is the most price effective and still provides those features. Can 
anyone comment about speed and reverse control of these motors using eg 
split windings or whatever?
Info I have found so far is here which is useful:
http://www.designnews.com/article/ca486922.html
Thanks,
Alistair.