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Discussion Starter · #1 ·
Hey, I'm interested in making my own fan controller and was looking for a little advice. I have a 92 in the back and an 80 in the front, both of which I plan on wiring up seperate. My question to you all is what I should use to control them. I'm trying to decide between using switches to change them from 12V - 7V - 5V (high, med, low), or a simply just using a rheostat. Can anyone point out any dis/advantages with each? Any suggestions to make this go easier? Thanks in advance!
 

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The 12-7-5v switch will be easier and able to handle more fans.

If you really want to build a controller, check this site out: http://www.cpemma.co.uk/
 

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The voltage switch is a great idea and is imployed on some common controllers. Now if you want to go ALL Next Gen. Make one with a 7volt 12volt 18volt and 24volt switch with reostats controlling the fan speed for TWEEK performance.
 

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you can acheve those Higher voltages by mixing the -5 Volt to the +12 for 17 vdc or the -12volt to the positive 12V for 24 vdc leads on the PSU
 

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Quote:


Originally Posted by Enigma8750
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you can acheve those Higher voltages by mixing the -5 Volt to the +12 for 17 vdc or the -12volt to the positive 12V for 24 vdc leads on the PSU

Modern PSUs don't have the -5v rail as it was dropped from the ATX years ago.

The -12v rail is only on the primary 20/24-pin plug. It will be a hassle to splice and wire to a controller.
 

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Discussion Starter · #7 ·
Thanks for the suggestions. Thinking the switches is probably the best idea. I can see two problems with the higher voltages idea though. In order to get at the -5V and the -12V wires I need to tap into the mobo 20/24 pin connector and I'd like to stick with modding the molex connector only. Also, I'm pretty sure the fans are rated for 12V and while they could probably handle higher voltages, I'm pretty sure they'll make them scream nice and loud, haha.
 

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Quote:


Originally Posted by floodx
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Didn't realize this, thanks for the info.

It was dropped as part of ATX12V v2.01 in June 2004.
 
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Thats for sure.. Just throwing Ideas around and thanks for the confirmation. I didn't know that the -5vdc had been eliminated from the newer PSUs.. thanks for the info. and BTW your right the fans will work with the higher voltages but your also right that your quiet quotant will drop dramatically.
 

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If you could find one on those old really small 200watt PSU and run it just for the fans that would give you the 17 and the 24 volts and not contaminate the voltage of the main PSU.
 

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You have the option of: +12v, +5v, and, +12V + (-5v) = 7v

I just built some thing like this not too long ago because I only wanted to control the Xigamtek BattleAxe on my video card, and wasn't going to buy a fan controller to control just that.

This is very simple, requires very little electronics knowledge, and is a good way to learn something about voltage regulation while you are at it. Very cheap to build too!

You need:
-1 LM317 voltage regulator (Good for 1 amp w/o heatsink)
-A 1k Ohm variable resistor
-*No filtering
-*No transient protection

*I mention specifically that you DONT need them, because the schematics I will provide, some will say you do. This is because often the LM317 is used to regulate voltage to much more sensitive devices than a simple fan. E.G. providing a voltage supply to generate a PWM, which needs to be PRECISE, and not have transients, and dirty waves.

Edit: Ok, I can't get Adobe to open on WIndows 7, sorry, give me a minute I will switch to Vista, so I can post schematics correctly.
 

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Quote:


Originally Posted by EntropyTTU
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You have the option of: +12v, +7, and, +12V + (-7v) = 5v

I just built some thing like this not too long ago because I only wanted to control the Xigamtek BattleAxe on my video card, and wasn't going to buy a fan controller to control just that.

This is very simple, requires very little electronics knowledge, and is a good way to learn something about voltage regulation while you are at it. Very cheap to build too!

You need:
-1 LM317 voltage regulator (Good for 1 amp w/o heatsink)
-A 1k Ohm variable resistor
-*No filtering
-*No transient protection

*I mention specifically that you DONT need them, because the schematics I will provide, some will say you do. This is because often the LM317 is used to regulate voltage to much more sensitive devices than a simple fan. E.G. providing a voltage supply to generate a PWM, which needs to be PRECISE, and not have transients, and dirty waves.

Edit: Ok, I can't get Adobe to open on WIndows 7, sorry, give me a minute I will switch to Vista, so I can post schematics correctly.


From a standard Molex plug.... you get:
+12v and GND = +12v
+5v and GND = +5v
+12v and +5v = +7v

All three voltages can be achieved by a simple 3 pole switch.
 

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Quote:


Originally Posted by DuckiHo

All three voltages can be achieved by a simple 3 pole switch.

Yep, that is exactly right.

This is just another way of doing that, and you are not stuck with three voltages, you can tweak it to what ever you want. Plus, this is lot more fun, and you actually learn a little about voltage regulation, and how to obtain a voltage that you need from a supply you are given at any time.

Either way, there is always more than one way of doing something and this is just another option.



BTW, one the link you provided DuckieHo, they have a walk through and schematics of exactly what I referring to:
Voltage Regulation

Although you can also use: 7812's, and nte956's which I have personally used a ton of. I would reccomend the LM317, as they have thermal shutdown, and over-current protection that has always seemed to work very well.
 

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Quote:


Originally Posted by EntropyTTU
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Yep, that is exactly right.

This is just another way of doing that, and you are not stuck with three voltages, you can tweak it to what ever you want. Plus, this is lot more fun, and you actually learn a little about voltage regulation, and how to obtain a voltage that you need from a supply you are given at any time.

Either way, there is always more than one way of doing something and this is just another option.



BTW, one the link you provided DuckieHo, they have a walk through and schematics of exactly what I referring to:
Voltage Regulation

Although you can also use: 7812's, and nte956's which I have personally used a ton of. I would reccomend the LM317, as they have thermal shutdown, and over-current protection that has always seemed to work very well.

True... Learing is a good way to get smrt.

The only downside to a voltage regulation is wasted energy. That being said... it's only a 1-3 watts.
 

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Quote:


Originally Posted by DuckiHo

From a standard Molex plug.... you get:
+12v and GND = +12v
+5v and GND = +5v
+12v and +5v = +7v

Yes, I just now realized what you were referring to and I totally switched those two voltages. Good point...edited...
 

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Discussion Starter · #20 ·
Thanks for all the replies. I think I have enough ideas to get started on a nice DIY fan controller. Something I'm trying to come up with now is a LED that will go out if the fan dies (messing with all these different voltages I see this being a good possibility). The most obvious would just be to wire a LED in series with the fan, but I highly doubt there's an LED that can handle as many amps as the fan will draw. So after some thinking the best I can come up with is to put a resistor in paralell with the LED, then put both in series with the fan. The resistor should take enough amps to keep the LED alive assuming I pick the right onel. The only flaw I see with this idea is will the resistor be able to handle the amps it's taking away from the LED without burning up (exploding) itself.

Most of my electrical knowledge comes from an engineering course I took during my first year before I went into my actual discipline (Nav Arch), while my practical knowledge is limited to playing around with LEDs, resistors, caps, etc on a bread board for fun. The one thing I do know though is things don't always work out in real life like they do on paper, so I'd like some input from someone who actually has some practical knowledge.

Thanks in advance!
 
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