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24v Fan @ 12v not working

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jadams

Member
Joined
Mar 27, 2002
Location
Burnaby, BC, Canada
This is not a cooling question so I didn't put it in the cooling section, but it is about a fan.

I have a 24v fan (Patriot DC, 1amp) and wanted to run it at 12v, but when I plug it in, the blades jerk but don't go around. I'm assuming it's just not getting enough juice. Am I correct?

I haven't tried it on it's own power cord yet, not sure if it will matter (400w Antec PSU).

So,

For all you electronic Know-It-Alls :) I was thinking of getting one of these:

http://www.allelectronics.com/cgi-bin/category.cgi?category=480&item=PS-104&type=store

http://www.allelectronics.com/cgi-bin/category.cgi?category=480&item=PS-459&type=store

to just run the fan. In all your knowledge do you think it would be very hard to set up? I would like it to turn on when I turn on the computer's power. (NOTE: When I get around to putting this in a system, It won't be using the Antec psu, not sure what kind I will get) I can use a soldering iron, and have no problems sticking my hands inside a psu. hehe assuming it's been discharged!!

Do I even need a 24v psu? Is there some way to get more volts from a regular computer psu?

Thanks for any help any of you can give. :)

Jeff.

EDIT: I know some of you would wonder why put it in..Because It's fun and would look cool. I'm thinking a very large tower case or a clear case, with the huge fan on the front bottom!
 

JimmyG

Member
Joined
Apr 21, 2001
Location
Michigan
There is no easy way to get more volts out of a 12v power supply. Some have adjustments, but it ony adjusts + or - 1/2 volt or so. Why use a 24volt fan? Fans are cheap. Even the most expensive ones are usually under $20.
 
OP
J

jadams

Member
Joined
Mar 27, 2002
Location
Burnaby, BC, Canada
Just because the fan would look cool in the front of the tower, thats the only reason, if I was just going for airflow and cooling I would just use a boring 12cm fan. ;) It's a 17cm diameter fan.

Jeff.
 

Breadfan

Inactive Moderator
Joined
Jan 4, 2001
Location
Northern VA
Ok this is a though I had late the other night, and it may be completely stupid and dangerous, but hey, why not tell it anyway!

My guess is that your fan will run on 12v, but will not start on 12v. It may need closer to 24v to start up, but once spinning could be toned down to 12v.

Now my question is whether or not this could work and be a good thing to do:

How about putting the fan on one line from the psu, and not putting anything else on it, and then wire in a 9v batter and a momentary switch on the 12v wire.

The theory would be that when you power up your system, you also hit the momentary switch which closes the circuit to the batter and pumps an additional 9v to the 12v line. That would give 21v that might be sufficent to start the fan.

Once the fan is started, let go of the momentary switch, the circuit to the battery is opened, and the line goes back to 12v to keep hte fan spinning.

Now, in theory, it sounds cool. But, i'm not sure if doing this would actually add the 9v to the 12v...my electrical theory is pretty rusty. And, I'm not sure if you'd risk pumping 12v through the battery and shorting it or anything...

But my thinking is that this would just add to the series and give you 21v...like having 3 1.5 volt batteries in a series would give 4.5...

Please someone correct me if I'm completely wrong.

Also, please someone comment on this becuase I don't believe you should try this without someone saying it'd be a good idea :)

It's just a thought I had...
Mike
 

dxiw

Disabled
Joined
Feb 7, 2002
or get a couple transformers.....
+ 12v->transformer->24vfan->transformer->12v -
 
OP
J

jadams

Member
Joined
Mar 27, 2002
Location
Burnaby, BC, Canada
Couple of Questions:

1. Would Breadfan's idea work?
2. Anyone know where I can find a 12v 17cm fan?
3. What does a transformer look like? And how do they work?

Thanks all!
 

Carnil

Member
Joined
May 29, 2002
Location
Spokane, USA
I wouldn't go with the transformer idea. Transformers only work with altenating current, so you'd need to add an inverter and a rectifier to the circuit in addition to the transformer. Breadfan's idea should work, or as an alternative, you could tap into either the -5v or -12v wires in the motherboard connector, for a total of either 17v or 24v between the wire you choose and the +12v wire.
 

Lt. Max

Member
Joined
Jan 28, 2002
Location
Seattle, but im Estonian
haha. well my friend had a 24v fan and we started it up by giving a push with our finger when the comp turned on.. it barely moved any air tho , it was 80mm too..

max
 

FunkDaMonkMan

Member
Joined
Dec 31, 2001
Connect the 12v to the positive and the -5v to the negative and that will give you 17v. see if that is enough juice.
 

Daemonfly

Member
Joined
Aug 18, 2002
Location
NW Pa
NO! That would completely short out +12v to the -5v !!! (hope you didn't do that yet!!)


+12v on the positive wire and the -5v on the negative wire.
 

Daemonfly

Member
Joined
Aug 18, 2002
Location
NW Pa
And the reason for the original try of a 24v on a 12v, is that many people have the 24v Comairs running on 12v just fine. They might be different models though...