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R.Rabbit

Member
Joined
Jul 19, 2002
Location
okinawa, japan

WyrmMaster

I'm a little teapot Senior
Joined
Dec 17, 2000
Location
Montana, USA
Yah, that shoud work. I havent seen an on-in-all-3 position switch before, but yah, it should work. You will have to wire straight 12v to one, straight 5v to one, and a combo of 12 and 5 to the middle one to give you 7v. For more detail see www.fanbus.com

And no, its not a problem for the psu, lots of people, myself included do this, and i have never heard of hurting a psu doing it. I DO like that 3 position switch though, good find.
 

Crazy Jayhawk

Member
Joined
Jul 14, 2001
Location
Hutchinson, KS
There's a rotary switch you can get at Radio Shack that's DP6T. Two poles, six positions. I tried to build a fanbus using those once, but I screwed up the wiring. They don't mark which posts match with which switch position, so it's good to have a multitester with you.

For this chart, the first column is for pole 1, the "high" wire, and the second is for pole 2, the "low" wire. Column three is the resulting voltage.

Code:
High   Low  Result
[color=yellow]12V[/color]    [color=black]0V[/color]   12V
[color=yellow]12V[/color]    [color=orange]3.3V[/color] 8.7V
[color=yellow]12V[/color]    [color=red]5V[/color]   7V
[color=red]5V[/color]     [color=black]0V[/color]   5V
[color=orange]3.3V[/color]   [color=black]0V [/color]  3.3V
[color=black]0V[/color]     [color=black]0V[/color]   0V
The second to last setting would be just about useless. :p You wouldn't get much airflow and some fans won't turn at that voltage.

The 8.7V setting is very nice. You get more airflow than at 7V while still keeping noise levels down.
 
Last edited:
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R.Rabbit

Member
Joined
Jul 19, 2002
Location
okinawa, japan
yeah that would be great but theres not too many radio shacks in japan, i have to order every thing on the internet
:(
 

WyrmMaster

I'm a little teapot Senior
Joined
Dec 17, 2000
Location
Montana, USA
I think that that would be nice, but to hard to use easily. What you could do though is get that 3 position switch and set it up with any voltages you want, 12, 8.7,7 12,7,5 ect. Thats what i would recommend.
 

Crazy Jayhawk

Member
Joined
Jul 14, 2001
Location
Hutchinson, KS
WyrmMaster said:
I think that that would be nice, but to hard to use easily. What you could do though is get that 3 position switch and set it up with any voltages you want, 12, 8.7,7 12,7,5 ect. Thats what i would recommend.
Time consuming to wire, easy to use. It's just a matter of dialing in the speed you want.

Also, the page said that supplies of the 3-position switch were limited. Not so with the rotary switch.
 

altoids1

Registered
Joined
Feb 13, 2002
Location
PA
I have a little different idea if you are an industrial person. How about a voltage divider for your fan. I am not that good w/ electronics but i found a page that might help out. A voltage divider is 2 or more resistors in series that give different voltages depending on where you tap in to it from.

here is a page that might help on wiring them

http://www.tpub.com/neets/book1/chapter3/1-39.htm


and here is a picture of how i was thinking this could be done.


circuit.bmp


trev
 

JDXNC

Member
Joined
Jan 16, 2002
Why not just wire a pot right to the 12V line then you can have any voltage from 0 - 12, its very easy, I did it in less than an hour. PM me if you want some details on it.
 

Crazy Jayhawk

Member
Joined
Jul 14, 2001
Location
Hutchinson, KS
JDXNC said:
Why not just wire a pot right to the 12V line then you can have any voltage from 0 - 12, its very easy, I did it in less than an hour. PM me if you want some details on it.
They're not usually rated for very high current loads.

A voltage regulator circuit would be best.
 

JDXNC

Member
Joined
Jan 16, 2002
Crazy Jayhawk said:

They're not usually rated for very high current loads.

A voltage regulator circuit would be best.

True, but a case fan or 2 doesn't draw a lot of current anyway. I used a 500 Ohm pot and its been working fine for the past few months with an 80mm LED fan on it.