Quantcast

Maximum PC

It is currently Tue Sep 30, 2014 3:01 pm

All times are UTC - 8 hours




Post new topic Reply to topic  [ 9 posts ] 
Author Message
 Post subject: Voltages on a Molex
PostPosted: Wed Mar 09, 2005 3:53 pm 
Team Member
Team Member

Joined: Wed Mar 02, 2005 9:12 pm
Posts: 270
Location: ill give you a hint. Potatoes
i just made my 1st test psu wich i plan on using for cooling my case. I need to no what wires are 12v 5v and ground on the molex connectors. also if i hooked my fan from the current wire its on now(yellow) to another wire could i get the fan to spin faster. wut i want to do is make a swich between the 5 v and the 12v to make my fan a 2 speed fan that i could change at the flick of a switch. if anyone knows how i mite go about this or if its even reasonable to do please tell me.


Top
  Profile  
 
 Post subject:
PostPosted: Wed Mar 09, 2005 3:59 pm 
King of All Voodoo2 Cards
King of All Voodoo2 Cards
User avatar

Joined: Tue Jun 22, 2004 10:41 am
Posts: 9316
I actually built one of those back in 1999.

The Yellow is the +12v, the Red is the +5v, and the black wire next to the colored wire are their respective grounds.

When I put it together a few years ago I used the 12v ground for both the +12v and the +5v lines and it worked fine. I had a low/high switching system. I even wired in a 12v red LED for fun.


Top
  Profile  
 
 Post subject:
PostPosted: Wed Mar 09, 2005 4:01 pm 
Team Member
Team Member

Joined: Wed Mar 02, 2005 9:12 pm
Posts: 270
Location: ill give you a hint. Potatoes
thanks for the quick response. ill be tryin that right now.


Top
  Profile  
 
 Post subject:
PostPosted: Wed Mar 09, 2005 4:29 pm 
Boy in Black
Boy in Black
User avatar

Joined: Thu Jun 24, 2004 1:40 pm
Posts: 24339
Location: South of heaven
Image

Electricity works on "potential", or actually...the difference in potential. It's really easy once you just get the simple addition and subtraction going. If you hook up to the red (5v) and the ground (0v), you get a 5v supply. If you hook up to the red (5v) and the yellow (12v), you get a 7V supply because it's the difference between the two. And, of course, the yellow and black give you 12v. See the simple math in there?

Take note that 5v may or may not be high enough to buzz your fan for a low setting, and 7v may be prefered. Either way...

To get 7v with a three way switch, you hook the neutral (reference) lead to the yellow. Then one side has the red, and one side has the black. This will have a switch position give you 12v (high), off, and 7v (low). It reads to that middle pole (12vv)as a reference. When you close a pair of contacts, it then supplies the differential. Just pay attention to your internal wiring in the switch.
Image
To get the conventional wiring with 5v low and 12v high, you change two wires around on the switch:
Image


Top
  Profile  
 
 Post subject:
PostPosted: Wed Mar 09, 2005 5:13 pm 
Team Member
Team Member

Joined: Wed Mar 02, 2005 9:12 pm
Posts: 270
Location: ill give you a hint. Potatoes
the 5v was enough to get it spinning but it didnt really move alot of air so ill skip that idea. would i be able to wire the fan into multiple 12v lines to get a 16v or a 24v on the fan. or would this probly kill the fan.


Top
  Profile  
 
 Post subject:
PostPosted: Wed Mar 09, 2005 6:42 pm 
Thoroughbred
Thoroughbred
User avatar

Joined: Sun Dec 26, 2004 7:10 am
Posts: 1839
Location: Left Coast
What you are attempting to do is somewhat dangerous because you could end up burning up your fan... so check out the fan specs first. What you want to do is connect the fan between two PSU outputs that gives you the desired voltage which is the difference between two PSU outputs (as Chumly posted):
Orange wire (+3.3v) to black wire (0v) = 3.3v
Red wire (+5v) to black wire (0v) = 5v
Yellow wire (+12v) to red wire (+5v) = 7v
Yellow wire (+12v) to orange wire (+3.3v) = 8.7v
Oarnge wire (+3.3v) to white wire (-5v) = 8.8v
Red wire (+5v) to white wire (-5v) = 10v
Yellow wire (+12v) to black wire (0v) = 12v


Top
  Profile  
 
 Post subject:
PostPosted: Wed Mar 09, 2005 6:47 pm 
Thoroughbred
Thoroughbred
User avatar

Joined: Sun Dec 26, 2004 7:10 am
Posts: 1839
Location: Left Coast
Anonsix wrote:
the 5v was enough to get it spinning but it didnt really move alot of air so ill skip that idea. would i be able to wire the fan into multiple 12v lines to get a 16v or a 24v on the fan. or would this probly kill the fan.


You could probably wire a 12vdc fan to 17vdc ( between the yellow and white wires is 17 volts, or red and blue wires is also 17 volts)... and probably shorten it's life. 24 volts will probably burn out the fan. I t would be best to look for a better fan.


Top
  Profile  
 
 Post subject:
PostPosted: Thu Mar 10, 2005 11:51 am 
Boy in Black
Boy in Black
User avatar

Joined: Thu Jun 24, 2004 1:40 pm
Posts: 24339
Location: South of heaven
That 17v was the most I've felt safe with. I hadn't done it in a while, but did it on a pair of Y.S. Tech 80mm's on an a past Alpha cooler for a P3 500. But that was very loud, but for some reason thought it was cool back then to be loud.

It's still a great option to have something adjustable via a fanbus. Something that could spin up using 17v at max, but can throttle it back to something more reasonable when you really don't need it (most of the time). Since you're thinking of making a switch, then 17v could be a nice "high". But if you just use the yellow and white, the low will be...5v? That's way low, so you may throw in a more complicated circuit to get a 7v low. Or...just run "low" as a normal 12v.

Or...find a real 3 position switch with all poles being used (no "off"). You don't really want an O-F-F position anyway. 17v up top as a "boost", 12v middle as normal, and 7v as "low". That sounds like a good setup actually. Then you can fiddle around later and add some multi-colored LED's to act as indicators. Red/Green is pretty common and can be made to indicate the "low" and "normal", then an additional blue could show "high". Something like that.

Great list there dude. I think that has all of the viable options one could use.


Top
  Profile  
 
 Post subject:
PostPosted: Fri Mar 11, 2005 5:10 pm 
Team Member
Team Member

Joined: Wed Mar 02, 2005 9:12 pm
Posts: 270
Location: ill give you a hint. Potatoes
thanks for all this but i decided to leave it at 12v. got a sumwhat small overclock like i wanted and improved my airflow by cuttin a hole in the front of my case and through an 80mm fan from an old PSU i had in there. case is pretty cool and not a bit louder.


Top
  Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 9 posts ] 

All times are UTC - 8 hours


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group

© 2014 Future US, Inc. All rights reserved.