In the past few weeks, I've done a lot of searching on this topic. As I look around me at the tangle of molex connectors, piles of ruined diodes and soldering iron burns in the carpet, I thought...perhaps I could spare someone else this pain. So, I've decided to compile a short guide on how to feed your fan something less than 12 V (use of the word "controller" is a little misleading for some of these). Most of these are quite simple, and hopefully one of these will meet your needs.
Why build your own fan controller?
- You're just looking to under-volt some fans, not control the universe.
- You just found SPCR today, and you want to do something NOW!!
- You're as cheap as they come. ("Hey, is that a penny??")
- It's fun to make stuff!!
The controller's we're going to cover fall into two basic categories...simple, and dangerous
. Well, perhaps not dangerous, but they might require using a soldering iron, or at LEAST use of a wire stripper. If using a wire stripper scares you, and your spouse won't let you use the other kind, then you'd better stick with the simple controllers.Simple Fan Controllers
Here's what you'll need:
- A molex connection. You'll often find a short section of wires connecting a male and female molex connector at the end of a fan connection, basically a power pass-through. These are great for modding.
- A molex pin remover. You can either buy one, or make one. Do a google on molex pin remover and you'll find info on both. I made mine using that guide and it worked great.
With those simple ingredients, we can make our simple fan controllers. There's two we'll try.
Slightly More Complex Fan Controllers
- The 7 Volt Mod
A little explanation on the PSU problem, since this is a common question. Essentially, when you create the 7 volt molex plug, you're taking current and feeding it back into the PSU. Normally, current only goes out the 12 V and 5 V lines of the PSU. To create the 7 V plug, you're taking current out the 12 V line, and putting it in the 5 V line. In theory, if the current is low enough, the PSU will be able to handle it. Just be aware that the PSU was not designed to do this, and there is anecdotal evidence that it can kill a PSU.
- The 5 Volt Mod
- Good: No danger to your power supply, and a really quiet fan.
- Bad: Not all fans start reliably at 5 volts, and you might not realize it until too late.
Both mods have virtually the same process, so refer to the following links for info on both mods.
cpemma's great guide
Mike C's guide
Bleedin Edge guide
Maybe the best guide (lots of pics!)
These controllers actually give you some measure of control. You'll be able to create a range of voltages your fan can use, and some let you switch easily between them.
For some of these, you WILL have to solder. Soldering is easy to do, and low risk (as long as you have good health and property insurance). If you're a newbie to soldering, such as I am, then these guides are REALLY helpful:A basic soldering guideNot only is this guide from NASA, but it is all movies!!!If PDF's are your thing...Another great guide, complete with a first aid section!
Now that you're fully armed with soldering knowledge...we'll start off with a controller that doesn't involve any of that!cmcquistion's Terminal Block controller
Mike C's fan speed switch
- Good: No soldering! And, gives you a wide variety of voltages to use.
- Bad: It's not very presentable, so you'll have to hide it in your PC. Also not very good for changing a fan's voltage "on the fly".
A PWM Controller
- Good: Allow for switching between two voltages. And no little magical electrical parts involved.
- Bad: Almost belongs in the simple controller section, except soldering is most likely involved here.
The well-known cpemma Diobus
- Good: PWM control adds some capabilities straight voltage controllers can't.
- Bad: Not all fans respond well to PWM, and this stuff makes the Diobus seem like childs-play.
Also shown here
, thanks to Alleycat
CPemma's site is excellent, by the way, for information, fan controlling ideas, etc. Highly recommended to read no matter which project you undertake.
- Good: Use a knob to switch between voltages while the fan is running. Add LED's for a visual indication.
- Bad: You should definitely understand wiring schematics for this one. And there will be soldering.
Well, I think this is a good start. I'll add other controller ideas as I hear about them. Also, this thread might be useful stickied in this forum for all the boneheads
out there who don't know how to gather information. Otherwise, if you don't feel this post is worth keeping in this forum, then don't reply to it and it will slowly sink to the bottom of the forum and die....along with my pride
Edit: Added PWM controller link, thanks to jamesm.