Can I make an LED fan spin the other way?

[Slatter]

Will reversing the power input polarity make Thermaltake's LED fans trun the other way?

[mtekk]

Probably not if there is any built in power regulation in the motor part, if you want a fan to blow instead of suck just flip it (the entire fan). Also most fans are designed to spin in only one direction for maximum efficiency (air flow).

[jbaldwinroberts]

You probably can get it to spin the opposite way if you really wanted but it would decrese airflow as the blades are designed to only work one way. Like mtekk said just flip the whole fan. It should have arrows on that tell you which way the fan spins and which way the airflow is.

-Joe

[xmastree]

You can't get it to run the other way. Reversing the power will not work.
The reason is that the motor contains electronics, which creates a spinning field and this field pulls the magnetised rotor round.
You could maybe hack the electronics, or rewind the poles, but as has already been noted, the blades are designed to move air one way. It would be less efficient turning the other way.

[Ichbin]

Baldwin says it best.

Just flip the fan. On all fans theres a total of 8 mounting screw holes. 4 each side.

[Xpirate]

The LED's might cause the fan to not run if you reverse the polarity. Diodes won't allow the current to flow the other way. Light Emitting Diodes are not an exception. But most fans probably will run backwards if you reverse polarity.

The other guys are right though. The blades are usually curved to be more effective turning the correct way. So you're better off just flipping the fan.

[xmastree]

But most fans probably will run backwards if you reverse polarity.
No they won't. They use brushless motors with built-in electronic controllers.

http://en.wikipedia.org/wiki/Electric_motor#Brushless_DC_motors
Midway between ordinary DC motors and stepper motors lies the realm of the brushless DC motor. Built in a fashion very similar to stepper motors, these often use a permanent magnet external rotor, three phases of driving coils, one or more Hall effect sensors to sense the position of the rotor, and the associated drive electronics. The coils are activated, one phase after the other, by the drive electronics as cued by the signals from the Hall effect sensors. In effect, they act as three-phase synchronous motors containing their own variable-frequency drive electronics

You think that's going to run with a reversed supply? :down:

[Xpirate]

No they won't. They use brushless motors with built-in electronic controllers.

http://en.wikipedia.org/wiki/Electric_motor#Brushless_DC_motors


You are right xmastree. I have at least one cheap fan that will run backwards, but it is not labeled as "brushless." I did some more reading on brushless DC motors. You could destroy it if you reverse polarity. I trashed a cheap brushless fan this morning just to see for myself.

[Slatter]

thanks alot to everyone for for the info. i could flip the fan but it would kill the look of the front bezel of the case. i will doing a lian li style case with just a clean mesh face with 3 blue fans in the front and nothing else. this is because i want the fans to work as exhausts and not intakes. the intake will be a 25 cm toyota air filter ( there is a lot of dust around where i'm at ). i have noticed the curves on the blade and had the exact same thought. may be i can some how cover up the fans with non-fan-grill-looking fan grills. :P

thanks again to everyone for their input, i will run some experiments regarding the design and get back to you guys.

[Slatter]

You are right xmastree. I have at least one cheap fan that will run backwards, but it is not labeled as "brushless." I did some more reading on brushless DC motors. You could destroy it if you reverse polarity. I trashed a cheap brushless fan this morning just to see for myself.

hahaha, dude sorry about your fan. its nice of you do the experiment for me. but the thermaltake fans are brushless, so....

I could also take the coil and flip that, that might work, but then we come to the problem of the blades being curved... :think:

[NightrainSrt4]

Are you talking about the Thermaltake fan that has like the ring of el wire around it?

I think thats why he just wants to reverse it so the lights will be facing the way he wants them. Hmmm... don't really know how to fix that.

If I am thinking correctly...

[Xpirate]

hahaha, dude sorry about your fan. its nice of you do the experiment for me.

It's not a big deal. I have a bunch of fans that I harvested from broken power supplies. My wife wants me to get rid of a lot of the computer junk.

[Slatter]

i will take some pics to show you what i mean...

[calumc]

I have an exhaust fan that I just filpped.
To improve the look I removed the sticker and stuck on a piece of some thin clear plastic

[Slatter]

I have an exhaust fan that I just filpped.
To improve the look I removed the sticker and stuck on a piece of some thin clear plastic

any chance we could see a pic of it?

[calumc]

Not much to show really:
http://farm3.static.flickr.com/2342/2178725668_be6e6b4205_o.jpg
It sits nicely atop my case coz it wont fit inside :p

[FuzzyPlushroom]

this is because i want the fans to work as exhausts and not intakes. ... ( there is a lot of dust around where i'm at )

With your PSU and all the case fans exhausting air, you'll end up with negative pressure inside your case. Believe me, the dust WILL crawl in through every available opening; I recently cleaned half a cat out of my Ultra Aluminus (which had, at the time, a ~100 CFM exhaust, plus the PSU, with no intake) and the animals don't even come into this room...

As odd as it sounds, balanced (or positive) airflow is the way to go. Make sure your intake fans suck in at least as much air as your exhausts blow.