12v cooling fans
 

Can I run two 12v fans from one 12v/120 converter?

More than likely yes. You just have to check the current (amps) out put of the converter and then add up the current draw of the fans. That being said fans don't usually draw very much current, so you should be fine.

As long as your fans are 12 volts DC,

Yes, they are 12v DC fans. Your typical Princess auto fans. They say .25amps. Power supply is 120v AC 20w / 12v DC 12w.

Thanks

You need to know how many mA the power supply is. Fans are 250mA each so PS must be a minimum of 500 mA.

Should be able to run 4 of those then

Yep good to go!

Yup, can run 4 .25mA fans. If you want real power, get a old computer power supply. They can power a ton of fans. Plus, you have 12v and 5v and you can mix it to get 7v So, you can run a fan at 7v no problem, little slower, less flow but alot quieter :D used to do that in my overclocked computers all the time.

In case anyone cares, to turn on a computer Pwr supply, connect the Green wire to ANY black one.
Yellow to Black 12Vdc
Red to Black 5Vdc
Yellow to red, 7Vdc

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 ;)

Right on guys. Thanks

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....

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.

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.

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.

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

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

Yes they will run at approx half speed.

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:

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. :smile:

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.

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

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.

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

Ummmm...I have had a couple power supplies were you have had to take the green to ground to make them turn on!!!!

Now that its been running the duel fans, I notice the power supply is fairly warm to the touch. How much would be normal? Cant say as I ever noticed it before when running a single.
Thanks

It should be fine, Doug. Power supply's can get warm, as long as its not HOT. If you can hold it, its ok. They usually are designed to burn out before they cause a fire or anything anyways

Thanks Dan. I put a little cooling fan to cool the power supply for the cooling fans. :lol: