12v cooling fans

[banditpowdercoat]

Originally Posted by Binare

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]

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]

Originally Posted by banditpowdercoat

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]

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]

Originally Posted by Binare

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.

[Doug]

Originally Posted by sphelps

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]

Originally Posted by Doug

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

Yes they will run at approx half speed.

[mike31154]

Originally Posted by Doug

They say 0.25 A. Whatever that is.

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]

Originally Posted by mike31154

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

[midgetwaiter]

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.