120mm PSU with a 12v burst fan start-up?

Bluefront · Post by **Bluefront** » Thu Oct 28, 2004 4:03 pm

Is there such a thing? I'm looking for such a PSU with a manual speed control knob, that gives a 12v burst to start the fan spinning.

Sounds pretty easy...

sthayashi · Post by **sthayashi** » Thu Oct 28, 2004 8:23 pm

Sounds almost easy enough to make yourself if you have any electronic skills (and knowing Bluefront, if you don't have said skills, I bet you could pick it up in a flash).

I'd test it out first, but a capacitor with one of the leads tied to 12V and the other lead on your Fan input might do the trick.

Caveat: I had to finish off a Champagne bottle tonight and I'm starting to feel it. My EE skills may not be as sound right now.

mathias · Post by **mathias** » Thu Oct 28, 2004 8:54 pm

Should be very easy to make if you were willing to manually give it the kick start every time by connecting an on off switch and the manual control in parrallel.

DryFire · Post by **DryFire** » Fri Oct 29, 2004 12:46 pm

could you make a stiwch that you'd pull back and it would apply 12v then when you let go it would switch to a resistor taht would apply the proper voltage?

I know some electrical engineers i could talk to if you can't think of anything.

Bluefront · Post by **Bluefront** » Fri Oct 29, 2004 3:02 pm

Well yeah....there are ways this could be wired up to manually do the trick. But I may as well just attach the fan to a manual fan controller. I'm really looking for a PSU to do this on full auto w/o any input on my part.

larrymoencurly · Post by **larrymoencurly** » Sat Oct 30, 2004 12:14 am

You could attach a capacitor across a resistor (or one of leg of a potentiometer) to cause a temporarily short at start-up. I do this across thermistors of fan speed-temperature controllers.

nbac · Post by **nbac** » Sat Oct 30, 2004 1:15 am

I used a 4700uF (or was it 6800?) cap from an old amp.
and connected it in parallel with a variable resistor (not a fanmate)
('+' on the psu side, '-' on the fan side). It works great and gives
my 4412FGL 2 seconds to speed up. Then the resisitor limits
the fan-voltage to 4V.

Skylined · Post by **Skylined** » Sat Oct 30, 2004 4:13 am

Do you really need that 12V startup?

I have a 120x38 fan and it's working just with 5V.

About the controller for the PSU, make your own.

http://members.lycos.co.uk/herdkilling/PSUC/

mshan · Post by **mshan** » Sat Oct 30, 2004 7:31 am

Doesn't the stock FSP350-60PN do that and have a manual speed controller knob? (http://www.newegg.com/app/ViewProductDe ... 966&depa=0)

I believe the primary complaint is that it has a linear fan controller that may spin up too fast.

It also seems that some people with very good airflow / low case temps are quite happy with the stock power supply (because, I believe, it doesn't spin up beyond it's minimum levels).

Edwood · Post by **Edwood** » Sat Oct 30, 2004 10:47 am

This little unit does just that.

http://www.siliconacoustics.com/noisema ... oller.html

But its not a reostat. Just a thermal controller, but it works really well. You can desolder the thermistor diode and extend it with wires and move it to a further location, like the PSU heatsinks, for example.

It's pretty small, you should be able to fit it inside the PSU case.

-Ed

Bluefront · Post by **Bluefront** » Sat Oct 30, 2004 3:14 pm

Edwood....I've seen that thing before, and it should do the trick if it works as advertised. You say you have one? If so, can it be under-volted? Its' lowest voltage is still slightly too high for my setup. Thanks for any info about this controller.

Putz · Post by **Putz** » Sat Oct 30, 2004 4:19 pm

Bluefront, I bet you could achieve the results you're seeking by attaching a variable resistor to the NMT-3 mentioned above, in place of the thermistor.

Post by **MikeC** » Sat Oct 30, 2004 4:21 pm

AFAIK, all the Fortron (and Fortron-sourced) 120mm fan PSUs that have a manual speed knob work this way. I am sure many others do. The 12V needs only to be the briefest pulse; just enough to overcome intertia, and then the voltage can be dropped right down almost instantly.

Putz · Post by **Putz** » Sat Oct 30, 2004 4:24 pm

I lied. After browsing the manufacturer's specs, I notice that the min. voltage on the output side is 5V, regardless of the temperature reported. But I also bet that a resistor on the output will reduce the min. (and max.) voltage further. The unfortunate compromise would be that the initial burst wouldn't be quite 12V anymore.

So, to recap, a variable resistor in place of the thermistor and a resistor on the output lead would combine to achieve something close to the results you are seeking.

Bluefront · Post by **Bluefront** » Sun Oct 31, 2004 2:34 am

MikeC's info about the Fortron's ability to kick-start it's fan is surprising to me since I'm running a Fortron Auhora, which has a manual control knob, but you'd never know about the 12v burst. There is absolutely no audible indication this is happening.

The two fan controllers I have that give a 12v burst, let the fans run at 12v for a few seconds....so that feature is quite obvious.

Nice to know and seconds my good opinions about Fortron.