Automatic Cooling Fan

hernanstafe · 15th March 2007, 04:12 AM

Anyone has an idea of the circuit for an automatic cooling fan? i mean that it turns on automatically when a sensor reaches certain temp...and i heard there are some that even change speed according to the temp, but i can't find schematics! i found something using tl88, but the datasheet doesn't say much.

head_spaz · 15th March 2007, 06:10 AM

http://www.cpemma.co.uk/thermal.html

blip1882 · 15th March 2007, 06:20 AM

Another option is to use a PIC (or PICAXE or Basic STAMP) which provides you with a lot of control options etc. The code and circuit would be pretty trivial if you have any programing skills.

jan.didden · 15th March 2007, 09:17 AM

Quote:

Originally posted by hernanstafe
Anyone has an idea of the circuit for an automatic cooling fan? i mean that it turns on automatically when a sensor reaches certain temp...and i heard there are some that even change speed according to the temp, but i can't find schematics! i found something using tl88, but the datasheet doesn't say much.

I published an article with a 4-speed temp fan control in Audio Amateur, I think early 80-ies. You may want to look it up at www.audioxpress.com .

Jan Didden

pinkmouse · 15th March 2007, 10:12 AM

Just about as simple as you can get.

http://www.diyaudio.com/forums/showt...993#post652993

edit: I just noticed you want one that turns off, mine is a variable speed one that never actually turns off.

jan.didden · 15th March 2007, 10:25 AM

Much simpler & more elegant than mine!

Jan Didden

pinkmouse · 15th March 2007, 10:33 AM

Basically, I'm not clever enough to do proper designs!

AMV8 · 15th March 2007, 12:41 PM

Hi hernanstafe

I use 12v cooling fans that operate from a 7812 voltage regulator. Or, if you want it to go slower use a 7809 regulator. I connect a temperature sensor into the fan supply circuit and set the sensor on the heatsink set at around 55 degrees.

I normally use one fan - at least - per heatsink.

I do not think you can get much simpler.

Don

jackinnj · 15th March 2007, 01:00 PM

I used the SG3525 PWM chip -- you can use the error amplifier to control the speed (Nat Semi had an application note on this) -- the SG3525 will source or sink 500mA so there's no need of a switching transistor.

hernanstafe · 15th March 2007, 02:11 PM

first of all, thanks everyone for your replies, and pink mouse, what's the ic used in your circuit?

EDIT: LM317!! sorry!

15th March 2007, 04:12 AM	#1
hernanstafe diyAudio Member Join Date: Feb 2007 Location: Argentina	Automatic Cooling Fan Anyone has an idea of the circuit for an automatic cooling fan? i mean that it turns on automatically when a sensor reaches certain temp...and i heard there are some that even change speed according to the temp, but i can't find schematics! i found something using tl88, but the datasheet doesn't say much.

15th March 2007, 06:10 AM	#2
head_spaz diyAudio Member Join Date: Mar 2004 Location: Arkansas	http://www.cpemma.co.uk/thermal.html __________________ Writing is good exercize for the texticles!

15th March 2007, 10:12 AM	#5
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	Just about as simple as you can get. http://www.diyaudio.com/forums/showt...993#post652993 edit: I just noticed you want one that turns off, mine is a variable speed one that never actually turns off. __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

15th March 2007, 10:25 AM	#6
jan.didden diyAudio Member Join Date: May 2002 Location: Great City of Turnhout, Belgium Blog Entries: 6	Much simpler & more elegant than mine! Jan Didden __________________ /Yes! Its out: Linear Audio Vol 5! I'm not an "accademic", just a plodder who loves a challenge - Ian Hegglun

15th March 2007, 10:33 AM	#7
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	Basically, I'm not clever enough to do proper designs! __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort


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15th March 2007, 06:20 AM	#3
blip1882 diyAudio Member Join Date: Sep 2005	Another option is to use a PIC (or PICAXE or Basic STAMP) which provides you with a lot of control options etc. The code and circuit would be pretty trivial if you have any programing skills.

15th March 2007, 12:41 PM	#8
AMV8 diyAudio Member Join Date: Jan 2005 Location: near london	Hi hernanstafe I use 12v cooling fans that operate from a 7812 voltage regulator. Or, if you want it to go slower use a 7809 regulator. I connect a temperature sensor into the fan supply circuit and set the sensor on the heatsink set at around 55 degrees. I normally use one fan - at least - per heatsink. I do not think you can get much simpler. Don

15th March 2007, 01:00 PM	#9
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	I used the SG3525 PWM chip -- you can use the error amplifier to control the speed (Nat Semi had an application note on this) -- the SG3525 will source or sink 500mA so there's no need of a switching transistor.

15th March 2007, 02:11 PM	#10
hernanstafe diyAudio Member Join Date: Feb 2007 Location: Argentina	first of all, thanks everyone for your replies, and pink mouse, what's the ic used in your circuit? EDIT: LM317!! sorry!

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