Computer Power Supply and Switch Wiring Questions

[rawfuls]

Originally Posted by BrianG

Ok, if you have a controller, why do you need any kind of switch?

Yes, assuming the controller is not using a switching buck/boost circuit, then the output can only be as high as the input. But, you tried running the fans from 5v before and they didn't want to start. So, if that's the case, then the controller must be outputting more than 5v.

Trying to get it a bit quieter

This is my "silent" build, and I feel getting it down to ~7V would be perfect when all I'm doing is writing up an essay..

The airflow is very powerful on low on 12V.

Well, when I mean I ran the fan on 5V, I meant through the controller.
I guess next time I'll try fan directly on 5V to settle this debate!

[What's_nitro?]

I have an idea...

1: Take ALL of the fans out of the computer.
2: Get a plastic tub large enough to put the computer in it.
3: Put the computer in it.
4: Fill the plastic tub with mineral oil.*

Voila! Your computer is now completely silent and you don't have to worry about dust!













*Submerging your computer in mineral oil may necessitate the use of an external CD drive.

[rawfuls]

Originally Posted by What's_nitro?

I have an idea...

1: Take ALL of the fans out of the computer.
2: Get a plastic tub large enough to put the computer in it.
3: Put the computer in it.
4: Fill the plastic tub with mineral oil.

Voila! Your computer is now completely silent and you don't have to worry about dust!

But..
Then it's all gooey... like linc.

[rawfuls]

Hey guys, finally gonna get started on this little project.

Would these work?
http://cgi.ebay.com/1N4001-Diodes-US...ht_3593wt_1102

also, how much more complicated would it be to add a small LED to determine if it's on/off (mostly just for cosmetic reasons, if it's easy, then maybe I should, but if it complicates stuff even more, I'll skip)...

Thanks,

[What's_nitro?]

1) Yes those will work. All of the 1N400X diodes have a 0.7V drop.* The last digit determines the max working voltage.

2) Most motherboards have a header for connecting indicator LEDs. "Power on" being one of them... Do you have the user manual for your mobo?

*See later post....

[rawfuls]

1) sweet, thanks, is there any diodes with a larger voltage drop?

2) I have those hooked up, I was thinking more along the lines of the fans.
If they're on, I guess a voltage regulator or a bunch of diodes (again) to drop the voltage + current down to the LEd.

[What's_nitro?]

1) 0o my bad... Vdrop on those diodes is actually about 1V*. That makes things easier.

2) Oh, the fans...... -_- You can just put the LED in parallel with the fan power leads with a resistor appropriate for the highest voltage it will see. It will just be a bit dimmer when the fan is running on a lower voltage.

* See BG's next post...

[rawfuls]

Originally Posted by What's_nitro?

0o my bad... Vdrop on those diodes is actually about 1V. That makes things easier.

Wait, I thought the 1N4001 had a .7V drop, or are they 1v..
You're confusing me!

[What's_nitro?]

I went and looked up the datasheet.....actually multiple datasheets from different manufacturers....they all said ~1V drop.

[BrianG]

It actually depends on the current flowing through them. Look at the curve near the bottom of the datasheet.

[rawfuls]

Originally Posted by What's_nitro?

I went and looked up the datasheet.....actually multiple datasheets from different manufacturers....they all said ~1V drop.

Oh giddy, now I only need 5 per switch, and not the 7 I was thinking of!

[BrianG]

Originally Posted by rawfuls

Oh giddy, now I only need 5 per switch, and not the 7 I was thinking of!

Again, it's not a certain fixed value. The higher the current flow, the higher the voltage drop. The 1n4001 will drop 0.8v @ ~.2A. Other resistors, such as 3A diodes (which are larger to handle V*I power losses) will drop less voltage at that same current.

[rawfuls]

Originally Posted by BrianG

Again, it's not a certain fixed value. The higher the current flow, the higher the voltage drop. The 1n4001 will drop 0.8v @ ~.2A. Other resistors, such as 3A diodes (which are larger to handle V*I power losses) will drop less voltage at that same current.

Okay, so I should just be using 7 diodes if I'm dropping 12V to 7V?

[What's_nitro?]

Yeah 7 will work fine.

[rawfuls]

Originally Posted by What's_nitro?

Yeah 7 will work fine.

Sweet, thanks.
Looks like no more gold star for you!