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So I just ordered a pile of Delta fans, and they draw 48 watts each at 12 volts DC. I need a fan controller that will run these, and it's gotta have balls. I will be wanting a minimum of 8 channels, and up to 32 maximum.

I don't need each channel to be individually controllable, although that would be a perk. As few as 2 channels could be controlled together (100 watts per channel), or up to 8 all controlled all at once. What I want to do is run the exhaust fans at 5-10% less than the intake fans, and the exhaust and intake will be paired together. PWM/Tach would be useful because then if either an exhaust or an intake fan would fail, the controller could speed up the one that hadn't failed in order to take up the slack.

I have no clue what something like this would cost. Experts, please let me know! Ideally I would be spending less than $200...? If you can provide PWM/Tach and possibly a cheap microcontroller to interface with the host system, that would be worth more. Perhaps integration with cgminer...? (Probably getting into fairyland wishes here...)

Hardware designers, hit me up! Post your spec and a quote on a single quantity here in the thread, or by PM if you wish.

EDIT: The fans that I bought have 4-pin PWM control. Not sure how this will affect the design, but it may make it so that no power transistors etc may be needed? Just a special square wave signal of varying duty cycle, and constant 12vdc to the fan, I think.

EDIT EDIT: Minimum is 6 ports, max is 24 now.

maybe just get a few of these?   :)

http://www.newegg.com/Product/Product.aspx?Item=N82E16811992009

Interesting, I hadn't seen those. Although they are strictly manual control though. I just edited the OP to show that the fans that I got have PWM control, which if I understand correctly will make it so that only a special signal needs to be sent to the fan instead of the fan controller actually needing to "dim" the voltage (which would require high powered transistors).

If the fans work as you describe, I could do that for 22btc and walk away with a nice profit.
All I'd do is program an arduino to output those signals, and be commanded via USB, which I could make an application for.
This all would be fairly easy, so I'd recommend doing it yourself. But if you really want to give me money I'd be happy to do it!

If you don't require actually switching the fans (ie, you have 4pin PWM fans) the difference between 50W and 1W is pretty minimal. A 64 or 100 pin uC would be plenty to run all the channels individually. If you require being able to PWM 32 channels at 4A, that's a more expensive (for hardware) project. Either way, development cost would be similar.

If all you need is to PWM fans manually with basically one setpoint (intake %, with exhaust being set a couple % lower), that would be a little simpler, especially if you're running PWN fans. That you could run with a few FETs, but you'd have less control.

Really, what you're asking for would probably require a custom PCB for 32 channels if you want to individual control. I'm an EE and I've done computer controlled fan controllers, but honestly it's completely not worth my time unless there would be a bunch of people interested in something like this. PCBs have a huge setup cost, so buying 50 units might only cost twice what buying 1 would cost. Likewise, even for a simple one $200 would be minimum wage once you actually get into how much time it would take to develop.

I'd take the 22 BTC offer. It'd be a great deal, you're really not be paying that much more than the hardware cost.

6x 50W channels with only one molex? Wow. Utopia.

Garr255, how many channels would that be, and would they be individually controlled? It would include some kind of PCB to plug into?

Here are the specs for the fans, can an Arduino handle multiple 25khz outputs? http://media.digikey.com/pdf/Data%20Sheets/Delta%20PDFs/PFC1212DE-F00.pdf
In addition, I am not 100% sure if that is exactly how it works, but that is what I inferred from the datasheet. It would of course need a powerful bus that could handle from 400 (8 fans) to 1600 (32 fans) watts, but at least the bus can be static and doesn't need to be power switched.

MrTeal, yeah that was my thinking, so I brought it here in hopes that an EE student might take up the challenge to provide something like it.

The idea is to start with 4 fans on the intake and 4 on the exhaust, and eventually move to as many as 16 on each side. The fans are rather expensive though  :-\

Looks like that one actually has 2 molexes, but I still think that is a little low (75 watts each, right?)

No, 30 watt max. Too low.

By molex specs it's a 11A per pin, so 12V*11A=132W. But usually molex connectors can handle around 30W, not more. It's HDD / CDROM connector, not designed for big current - as a consequence that it's has more thin cables and connectors than meant by specs.

BTW - What's the model of the fan? 32 channels of 48W is quite insane, that's more than two horsepower. The explosion proof exhaust fan I'm looking at for the paint booth I'm building in my garage is only 1/2HP, and it's rated to move over 4000CFM.

Delta PFC1212DE-F00. 252 CFM each, 32 mmH²O static pressure, 66 dBA.

:o I hope you got a great price. Those aren't cheap fans.

I assume this is for controlling fans for a large mining farm? Did you look into using larger fans? Something like this decent box fan (http://www.amazon.com/Air-King-20-Inch-3-Speed-9723/dp/B0007Q3RMA) could give you over 2000CFM on 170W. Ducting would be more of an issue than with individual fans, and static pressure would likely be worse, but if depending on your application that might not be a problem. Control wouldn't really be any tougher than controlling a 12V fan, though you wouldn't get a tach output. You'd use half as much electricity, and the capital costs would be much, much lower.

Check out my sig - that's what this is for. ;D

They are 120mm each, so I can make a wall of fans 2 high and 4 wide fit into a rack formfactor, and the additional channels are if I want to stack them 2 deep for server-grade redundancy.

EDIT: I just realized that in a standard 19" width, I can only have three 120mm fans next to each other, not 4. So that makes my minimum number of channels 6, and my maximum number of channels 24, not 8 and 32.

With a bit of custom code, the arduino is fully capable of a 25khz pwm signal. I'd prefer sending out a tested product, so if you do plan on purchasing more fans, could you send one or two to me, then I'll send them to you with the finished product? Also, what kind of enclosure would you want for this? I could also do manual controls if you'd like, which could override computer controls with the flip of a switch, or just act as a fallback. The arduino has six pwm channels, but if I am correct, I think the rest could be hackable for this purpose. Keep in mind this will be my first project for someone else, and I'm not an EE student (yet), just a high school one.

-Garrett

Sure I could send you a fan or 2. I wouldn't need any special enclosure, as long as the PCB has some kind of mounting holes. The PCB is what worries me most, actually, since it will still need a large amount of power going through it, even though it will just be a DC bus. I haven't gotten the fans yet, so I don't know whether they have a mating connector on them or whether they are bare wires. If they are bare wires, then I would just solder the PWM signal wires onto your board, and connect the rest of the stuff to my massive 12v bus.

As for manual controls, if something fails you shouldn't need to do anything. With no PWM signal at all, the fans ramp up to full blast. I'll let you know when the fans arrive.

Okay, I just thought that might be a nice feature. Let me know when you get the fans and I'll get started. This rig is going to be awesome!

I got the fans in yesterday, and they came with a connector that doesn't fit anything I have ever seen, so I chopped them off. The wires are also very thin, but they spin up fine. PM me your shipping address and I'll send you a couple of them to develop with.

I'm figuring the easiest way to do this would be to have several open solder points that I could hook up the PWM wires to, and I'll take care of the power wires on my main 12v bus. Would this have tach reading capability, or would it just do PWM? These fans take PWM for speed control, as well as providing a tach output to read the current speed.

Yeah, that's what I'll do

I don't know whether I'll be able to read the tach data. I'll give it a shot though.