5v source?

[blk03MitsuES]

had a laptop, keyword "had".......among the many pieces that i kept, there's a couple of really slim fans. they actually push quite a bit of air. figured i'd find a way to put it on the back of the case. there's a gap big enough to put the fan in there. i saw on a magazine once that this one guy put a shield on the mobo. He's theory was that the small gap between the shield and the mobo cause the air from a fan to move more efficiently across the mobo. so that's what i'm planning on doing. but i came to a little problem. the fan runs on 5 volts. i know all the molex conectors are 12v. i had planned on slicing the 3 pins of the fan and conecting them to a molex conector. but will the 12v source do anything to the little 5 volts fan? how about the connector for the floppy disk, how many volts is that?

[Redundant]

On a molex connector there are 4 wires:
+5v
ground (Black)
ground (Black)
+12v


Just connect the fan to the 5 volt line (I think it's red; test it with a muitimeter to be sure) and a ground and you shouldn't have any problems.

As for the 'shield' across the mobo, search for Defyant's work logs (on this website) as he uses that often and most have a small fan built into the shield.

Sorry for the voltage mixup, I could've sworn there was a 3v somewhere... At least I got the colors right lol

[tybrenis]

On a molex connector there are 4 wires:
+3v
+5v
+12v
ground (Black)

Just connect the fan to the 5 volt line (I think it's red; test it with a muitimeter to be sure) and ground and you shouldn't have any problems.

As for the 'shield' across the mobo, search for Defyant's work logs (on this website) as he uses that often and most have a small fan built into the shield.

Are you sure? I'm pretty sure that the wires are the following:

RED: 5v+
BLACK: 5v-
BLACK: 12v-
YELLOW: 12v+

I have been using computer power supplies in another project and thats what I have been pulling with my multimeter...

[LiTHiUM0XiD3]

u would be very much correct tybrenis...... have no idea where u got ur information redundant lolz

[blk03MitsuES]

oooh nice, so it's just a matter of pulling out the meter to check the volts on the molex. will look into Defyant's logs

[tybrenis]

Yep. if you look at a four pin molex the voltages will always be the same. If you want 5 volts then hook up your positive to the red cable and then your negative to the black one right next to it and you're good to go. =D

[DaveW]

RED: 5v+
BLACK: 5v-
BLACK: 12v-
YELLOW: 12v+

There is occasionally mix-up here. Voltage is a measure of 'pottential difference'.

Here is the actual voltages:

Power Supply plug 5.25-inch 4-pin Molex

Pin# Color Function
1 Yellow +12V DC
2 Black Ground
3 Black Ground
4 Red +5V DC

Power supply plug 3.5-inch

Pin# Color Function
1 Yellow +12V DC
2 Black Ground
3 Black Ground
4 Red +5V DC

If what you were saying was correct, then the voltage between the +12v and the -12volt would be 24 volts, and 10 volts across the -5 and +5 lines. This would also mean that the -5 volts and the -12volt lines were, for some reason, both the same colour.

This is a very commonly made mistake, but don't worry about it. It makes a difference mathematically, but most Americans will consider the voltage over -12volts and +12volts as 12volts, mentally equating -12volts to ground. This is probably because it took a long time for Electricians to actually standardise the terminology, in which time America decided to make their own. Some of the old American system survives in things like this.

Hope that helps.

-Dave

[Redundant]

Yes, you guys are right. As you can see, I'm still a noob. lol. I'm so embarrassed.
Edited and fixed.

EDIT: This Defyant thread has some pics of the mobo cover and fan.