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Help with a DIY adjustable speed fan setup

F

firebirdude

Member
I'm working on a little side project. I need to use three fans off one 12VDC power supply, but I need at least two of them on a speed controller. The third fan needs to run at full speed at all times. So can I just run all the fans in parallel, but put the potentiometer inline with the two fans needing controlling? Like this?:
fansl.jpg
 
firebirdude said:
How is that cheaper than a simple pot/variable resistor?

Shouldn't one of these work?
http://cgi.ebay.com/2-Port-3-Pin-CP...ltDomain_0?hash=item27ae9f5e65#ht_2343wt_1165

Thanks for your input btw 🙂
Click to expand...

Depending on the Amperage of fans your connecting those wont hold out.

Read how many amps they can handle on 1 channel.

Typical fans will run .25A -> .58A

So you really need to plan the Amps out when you build that channel.

The rheobus is tested @ Output current: up to 1.67 A
 
True. All three fans are rated at .37A

I may have an old 5.25" bay fan controller like that laying around somewhere.... lemme see if I can bastardize that into something workable for me.lol
 
firebirdude said:
True. All three fans are rated at .37A

I may have an old 5.25" bay fan controller like that laying around somewhere.... lemme see if I can bastardize that into something workable for me.lol
Click to expand...

that would be your best bet.
 
it's not working. 🙁
This is the one I have
SuperFlowerFanMasterSF609.JPG

It has inputs for +12VDC, +5VDC, and two grounds. I assumed the 5VDC line is for speed monitoring or the LCD display or... something. And that the 12VDC is the actual power set/regulated to the fans. So I attempted to connect just the 12VDC and the grounds up, but I get no power out to any of the fans.🙁
 
Well u could try dropping in a larger mosfet on that first link.

And then adding a sink.

Having a larger mosfet would allow more amps.

But as it stands, id be hard pressed to trust more then .5amps on that original controller you listed.
 
The 5.25" fan controller I pictured above just uses pots to regulate output fan voltage correct? All the rest of the components on this controller are more for the LCD screen/alarms/temp sensors/fan speed reading/etc?

I'm thinking about desoldering a couple of the pots from the circuit board and soldering my +12V wires right to the pins on it. Then trash the rest of the controller.

Also the PCI slot controller I first linked to says it can take up to 1 amp ???

As a side note, I'd just buy a high amperage pot from radio shack, but they want like $15 for one.
 
Thank you for all your input. But I think I'm just going to buy one of the cheap PCI slot fan controllers I have linked above. They are under 5 bucks shipped and say they're good up to 1 amp. Keep in mind that only two of my three fans will be on the controller. So even if the 1 amp rating is inflated, I'm still well below that.

The rheobus is nearly $22 after shipping and is still more physical bulk than I need. The pots linked to in the post above would likely work perfectly, but the minimum shipping charge is $7 bringing totals ~$16-$18.
 
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