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-   -   12v cooling fans (http://www.canreef.com/vbulletin/showthread.php?t=53950)

banditpowdercoat 06-29-2009 01:21 PM

Quote:

Originally Posted by Binare (Post 431801)
Don't let bandit confuse ya here Doug, you can run 4 250mA fans, don't go searching for .25mA fans, doubt they exist and you'd be able to run 4000 of em if they did ;)


He allready SAID he had 2 25mA Fans So they are avail. My above post should have read 25mA not .25mA But that should be easy to figure out....

sphelps 06-29-2009 01:37 PM

If you find the fans are too noisy you can run them in series which will give each fan 6v. I do this quite often with those PA fans as they do tend to be a little noisy at 12V.

Binare 06-29-2009 01:55 PM

Quote:

Originally Posted by banditpowdercoat (Post 431804)
He allready SAID he had 2 25mA Fans So they are avail.

Gettin closer, 250mA, not 25mA still a huge difference. And I still doubt 25mA 12v fans can be had. Don't get upset, wrong information can lead people on wild goose chases to find stuff that don't exist, or won't work.

In Dougs case, we are talkin about a 12vdc 1a supply with 2 250mA loads. The supply is more then enough to handle the load.

Don't let your feelings get so hurt when information is corrected mate.

oilfieldsafety 06-29-2009 02:56 PM

Fans
 
If you are looking for quiet 12v fans I found some fantastic ones at Memmory Express, they had some as quiet as 7.8 db.

Doug 06-29-2009 05:24 PM

Quote:

Originally Posted by Binare (Post 431808)
Gettin closer, 250mA, not 25mA still a huge difference. And I still doubt 25mA 12v fans can be had. Don't get upset, wrong information can lead people on wild goose chases to find stuff that don't exist, or won't work.

In Dougs case, we are talkin about a 12vdc 1a supply with 2 250mA loads. The supply is more then enough to handle the load.

Don't let your feelings get so hurt when information is corrected mate.


They say 0.25 A. Whatever that is. :lol:

Doug 06-29-2009 05:25 PM

Quote:

Originally Posted by sphelps (Post 431806)
If you find the fans are too noisy you can run them in series which will give each fan 6v. I do this quite often with those PA fans as they do tend to be a little noisy at 12V.

Thanks Steve. May try that. Will they then run slower also?

sphelps 06-29-2009 05:28 PM

Quote:

Originally Posted by Doug (Post 431858)
Thanks Steve. May try that. Will they then run slower also?

Yes they will run at approx half speed.

mike31154 06-29-2009 05:42 PM

Quote:

Originally Posted by Doug (Post 431856)
They say 0.25 A. Whatever that is. :lol:

That is 250 milliamps. 0.250, take it to 3 decimal places for milli which means thousandths, which is what the 3rd decimal place designates.... or a quarter of an amp, if you wish. Never a bad idea to get a power supply that has a good buffer of extra capacity (within reason). More efficient and less heat produced by a larger supply running at less than full capacity, than a small one trying to put out its max power. Not to mention, safer.

subman 06-29-2009 05:51 PM

Quote:

Originally Posted by mike31154 (Post 431866)
That is 250 milliamps. 0.250, take it to 3 decimal places for milli which means thousandths, which is what the 3rd decimal place designates.... or a quarter of an amp, if you wish. Never a bad idea to get a power supply that has a good buffer of extra capacity (within reason). More efficient and less heat produced by a larger supply running at less than full capacity, than a small one trying to put out its max power. Not to mention, safer.

He only wants to run 2 so thats a 50% buffer thats pretty good:mrgreen:

midgetwaiter 06-29-2009 07:15 PM

Do you know if that is a regulated power supply Doug?

A regulated power supply will deliver 12v at anything up to it's rated current. An unregulated power supply, which most cheap ones are, will only deliver 12v at exactly it's rated current. If you are drawing a smaller amount of current the voltage goes up.

In your situation I would expect your power supply to deliver something more like 14v at half it's rated current. This is not a big deal from a safety POV but I've noticed that it tends to make the fans noisy if they are driven too hard. You can just add a resistor to the circuit if you need to match the current draw.


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