How do I quiet down a 48v fan?

[Calderwood]

I have a 48v 19w 200cfm fan on my cnc that I use to exhaust the electronics box. This thing is WAY too loud. Can I use a resistor to quite this thing down? If so, what resistor do I need? Is the a better idea than the resistor? I went overboard when I bought it and I don't really need this much air flow so I'm not worried about it not moving as much air after.

 

[EeePee]

47 volts?

46?

...

:mrgreen:

 

[puddin]

I'd stick some plastic over the intake and it should take care of it's self........... does it sound like a bearing went out?

 

[The Violator]

I'd stick some plastic over the intake and it should take care of it's self........... does it sound like a bearing went out?

All that would do is increase the sound by adding a restriction.

 

[greenjk]

What about a variable resistor so you can dial it up or down.

 

[puddin]

All that would do is increase the sound by adding a restriction.

Won't make noise if it won't turn on.

 

[wings_of_fire]

Turbulent flow of air causes noise.
Laminar flow of air does not cause noise.

The air getting inside the fan is somewhat laminar, but the air getting outside the fan is turbulent. Fabricate some directional fins(like those in our car cabin,ac outlet) that will straighten the airflow out of the fan. The distance of fin body should be as close as possible to the fan body. That will reduce considerable noise.

 

[Duuuuuuuude]

 

[EeePee]

The fan will just knick those, so no point.

Knick and fling. Watch out!

 

[The Violator]

What about a variable resistor so you can dial it up or down.

Some kind of potentiometer/rheostat might work.

 

[EeePee]

You mean a pot?

 

[Duuuuuuuude]

Or, have some fun and make it sound like a race car.

and

 

[EeePee]

I just read something about killswitch getting had on ebay about a baseball card.

See that?

 

[Duuuuuuuude]

You mean a pot?

Like this?

 

[Duuuuuuuude]

I just read something about killswitch getting had on ebay about a baseball card.

See that?

Aye. I seen that.

 

[Calderwood]

47 volts?

46?

...

:mrgreen:

Yeah but what resistor do I need to drop the voltage down an appropriate amount?

I'd stick some plastic over the intake and it should take care of it's self........... does it sound like a bearing went out?

It's brand new. The bearings are quiet but at 4000rpm the rush of air is louder than I want to deal with.

Turbulent flow of air causes noise.
Laminar flow of air does not cause noise.

The air getting inside the fan is somewhat laminar, but the air getting outside the fan is turbulent. Fabricate some directional fins(like those in our car cabin,ac outlet) that will straighten the airflow out of the fan. The distance of fin body should be as close as possible to the fan body. That will reduce considerable noise.

When I fired it up for the first time I though the grill I had in front of it was causing cavitation but it is every bit as loud out of the box. There really isn't any room to make fins in front or after the fan.

 

[EeePee]

You can't drop voltage? Why 48 volts?

Transformer over resistor unless you might want a space heater.

 

[csb510]

As mentioned earlier, a rheostat/potentiometer is what you need. When I was heavily into computer modding/overclocking I had a gang of fans moving lots of air in the computer case, thats before I went liquid cooled. Then came RCs.

 

[JohnRobHolmes]

What type of fan motor? AC or DC power?

 

[C*H*U*D]

48v is a lot to drop with just a resistor or pot. I would use a pot with a voltage regulator, but I would also have an electronics guy take a look at what I was planning to make sure it's a good idea. Luckily I know someone much smarter than me in that area, and he works for beer "thumbsup"