CPU Fan

[Jonathan]

Hey guys. The pastor let me take home the old PC at church, for parts.
I considered trying to build it up to working order but just don't have the
$ right now. Point being, I took out the CPU fan for a DIY project for my
'scope, and need to know: What are the three wires for? I got a yellow,
red, and black. Red and black for positive/negative? Whats the yellow?

Pretty much snipping the plug off the end and wire it around a 6v battery.
BTW, this came from a old 500, 600, or 700mhz PC, Compaq; I forget the
actual speed but its in that range Thanks,

[Andy]

The 3rd wire is for monitoring temps. of the CPU

[ChrisTech]

If its a Compaq Presario 5000 (pic attached) it should be 700Mhz - 1Ghz. (PIII/Celeron/AMD Athlon (K7))

Pretty big range on those. I see quite a few of those come in to be fixed @ work.

[dammitjanet]

The 3rd wire is for monitoring temps. of the CPU

actually its more than likely to be monitoring the fan speed not the temperature. Most motherbaords rely on surface mount sensors on the motherboard.

[Andy]

Oh ya..the fan speed...thats it

[Jonathan]

Nah but that looks like the family PC, almost
Its all white front... I wonder, do you guys think the
fan would still function if I removed the yellow wire
completely?

[Dan]

Sure it would Jonathan. It's just reporting speed back to the mobo.

Good luck on the DIY!

Nah but that looks like the family PC, almost
Its all white front... I wonder, do you guys think the
fan would still function if I removed the yellow wire
completely?

[dammitjanet]

yes it should, however you may need to turn off the sections in bios that deal with processor fan speed, like the temp/fanspeed modulation and fan speed alarms.

[Jonathan]

yes it should, however you may need to turn off the sections in bios that deal with processor fan speed, like the temp/fanspeed modulation and fan speed alarms.

Its going to be hooked up to a 6v battery (for now) and hanging off the
back of my 'scope, so the mobo going on bout alarms don't matter to me...

I'll let you guys know if it work.

[Dan]

Jonathan,

If I'm not mistaken the fans are usually 12V so you'll only be running it at half speed. Assuming that 6V is enough to get it started that is.

[Jonathan]

Jonathan,

If I'm not mistaken the fans are usually 12V so you'll only be running it at half speed. Assuming that 6V is enough to get it started that is.

Yea, it does say 12v on it. I've talked to a few who have done simular stuff,
and they all report it works fine. I just hope this works

Knowing my luck it won't work because of the
battery, or the fan will just out right die on me

[Dan]

hahahah!

Let me know if it does and I'll send you one, I have a few kicking around

Good luck!

[Buddha]

Yea, it does say 12v on it. I've talked to a few who have done simular stuff,
and they all report it works fine. I just hope this works

Knowing my luck it won't work because of the
battery, or the fan will just out right die on me

Not all 60mm fans (which I guess you mean by CPU fan) can run on 6 volts but some can.

If it's an 80mm then your probably out of luck.

Could always try putting together a voltage doubler with a couple diodes and a transformer.

Good luck.

[Jonathan]

Okay the other fan was waaaaaaaaaaaaaaaaay to small- didn't
move enough air. Another astro dude secured me a nice big fan
from his work, pretty dusty. Super short wires on it though

I got the 6v and stripped the ends off the wires and tested,
it works fine and pushes a good amount of air. I just need to
find some sort of wiring next time I go to the store and extend it,
so I can keep the fan hooked up for any angle the scope is at.