12v cooling fans

[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.

[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.

[Doug]

Originally Posted by 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.

Not sure but its a PA cheapie.

So could I just put some form of speed controller on them? Thats resistor based is it not?

I,m thinking I should just by another and have one come on with the halide and the other fan regulated by the RK2 temp controller.

[Skimmerking]

i would just get the multi power one that i have there doug that ones tha go from 3w 5w 7w 9w 10w 12 w

[mseepman]

That's what I did...I run a 1000mA variable power supply and connected them to 3 Princess auto fans...and run them at the voltage that makes the least noise while providing enough air.

Still ended up being too loud for me so I bought some good fans at www.ncix.com and they push 3x the air at half the noise. In my opinion, other than their tiny size, the PA fans are a temporary solution if noise or lack thereof is important to you.

[midgetwaiter]

Originally Posted by Doug

Not sure but its a PA cheapie.

So could I just put some form of speed controller on them? Thats resistor based is it not?

Yep, technical term is potentiometer but it's really a variable resistor.