The ultimate beginner's guide to PC FANS

[Matanuskan Flo]

Scrubninja,

first of all, awesome thread, for suuuure. + Rep. I was thinking the whole time I read this thread & imagined a different way to ensure Stealth in regards to the movement of air from fans causing noise. I immediately thought of my Jawbone 2 w/ noise canceling technologies. Before going further on the forum, I did some research. White noise generators/speakers have been around for a while & is a simple process. However, true noise cancellation has been an elusive notion that only recently has been successfully patented & demonstrated. I figured microphones & whatnot would be needed & only 1 particluar sound, space, or frequency would be possible to mask/cancel. This is now not the only method to, in essence, record the positive waves & send back exact negative waves to cancel out the sound. The following link is for a device specifically made to cancel out Fans' noise. It does so by digitally converting the sound waves with constant variable capabilities depending on fan speed/air flow.

http://www.freshpatents.com/-dt20090716ptan20090180637.php

I do not know the price of this device or whether it is even for sale yet. But, in time, there will be many of these devices. Perhaps, some computer savvy or tech savvy individual can make their own or already have. But, I would love to just use the most powerful fan necessary w/o worrying about noise for any situation. As long as everything is proportional, bigger & badder exhaust or intakes can be used. then more lights can be added, etc etc etc. this is something I am going to keep my eye on for suuure.

 

[le crunch]

Thank you ScrubNinja for this information. I found it very useful when fitting a fan to my cab. I too use these electrical connectors - they are a huge improvement over electrical tape.

 

[ScrubNinja]

Cheers crunch, yeah I use those for every electrical connection I make now. Really safe & secure. They may well get used for 4-pin Pl-l bases in my new setup too.

Woah thanks for the illuminating post, Flo!! I never really thought about noise cancellation. I have actually messed with phase cancellation before in a different context! Very interesting idea, man. This is from wikipedia:

Sound is a pressure wave, which consists of a compression phase and a rarefaction phase. A noise-cancellation speaker emits a sound wave with the same amplitude but with inverted phase (also known as antiphase) to the original sound. The waves combine to form a new wave, in a process called interference, and effectively cancel each other out - an effect which is called phase cancellation. Depending on the circumstances and the method used, the resulting soundwave may be so faint as to be inaudible to human ears.

A noise-cancellation speaker may be co-located with the sound source to be attenuated. In this case it must have the same audio power level as the source of the unwanted sound. Alternatively, the transducer emitting the cancellation signal may be located at the location where sound attenuation is wanted (e.g. the user's ear). This requires a much lower power level for cancellation but is effective only for a single user. Noise cancellation at other locations is more difficult as the three dimensional wavefronts of the unwanted sound and the cancellation signal could match and create alternating zones of constructive and destructive interference. In small enclosed spaces (eg the passenger compartment of a car) such global cancellation can be achieved via multiple speakers and feedback microphones, and measurement of the modal responses of the enclosure.

Modern active noise control is achieved through the use of a computer, which analyzes the waveform of the background aural or nonaural noise, then generates a signal reversed waveform to cancel it out by interference. This waveform has identical or directly proportional amplitude to the waveform of the original noise, but its signal is inverted. This creates the destructive interference that reduces the amplitude of the perceived noise.

The active methods (this) differs from passive noise control methods (soundproofing) in that a powered system is involved, rather than unpowered methods such as insulation, sound-absorbing ceiling tiles or muffler.

The advantages of active noise control methods compared to passive ones are that they are generally:

* More effective at low frequencies.
* Less bulky.
* Able to block noise selectively.

 

[Paranoid one]

Hey there! How's it going scrubbs? (guess who I am) lol no jk don't.
So i got my Pc back.. finally.. took ages for that. Ok, so i got a problem which I'm not to sure of but i have like 4 sources confusing me. I need to install my fans and than I'll be all set to take off.
Allow me to tell you the specs on the fans and which kind of ac>dc adapters i have.

Specs:
1st fan: 120 x 25mm intake fan with 3-speed control. (thinking of running this fan on slow or medium.

Speed (RPM):high-2000, medium-1600, low-1200
Input Currentmax)high-0.24A, medium-0.2A, low-0.13A
Noise:===== high-30dBA, medium-28dBA, low-25dBA
Input power: high-2.9V, medium-1.4V, low-1.6V

2nd fan:140 x 140 x25.4mm exhaust fan with 3-speed control.(thinking of running this one at max or medium)

Speed (RPM):high-1500, medium-1100, low-700
Input Currentmax)high-0.28A, medium-0.20A, low-0.15A
Noise:===== high-31.8dBA, medium-21.4dBA, low-0.19.8dBA
Input power: high-3.36V, medium-2.4V, low-1.8V


Alrighty then, here is my big "Q".

What should the specs of my adapter be if i were to run these fans off one power source without burning out the fans/making them not as powerful (how much they blow/suck)?

I have:
12V 500mA
12V 300mA
Now i have added both amp'age for selected speeds, Intake-medium=0.2A and exhaust-high=0.28A

Now I've read if you use a 12v dc adapter the voltage gets cut in half... which makes the fan weaker, but quieter...

So can you help me out on this one?

Thanks for your time

and if not

than...

 

[maryjohn]

your fans together will overload either of those power supply. You would have to run them in a series, which you already don't want to do, since it will cut power in half. I am not sure if it is feasible, but both put together would do the job. Never tried that.

Get yourself to radio shack or whatever they have where you are, they have adjustable wall warts up to 1.5 amps. You'll get a controller and power all at once. Another option to go full time 12v is the adaptor from an old nintendo or such.

those are very low powered fans, how big is the case and how much wattage? cfl?

 

[ScrubNinja]

Gday Para! Thanks for letting me know who you are, and good to see you back. I'm afraid I gotta disagree Mj, the draw is .48A so the .5A is gonna cover both fans with a little bit of overhead.

You would want to remember not to accidentally switch the intake to full speed in summer of course. You may even want to hook the intake up to the 300ma, and the exhaust fan up to the 500ma. Then it's impossible to overload if switched wrong, and you have the added benefit of being able to turn your intake fan off at lights out, automatically via the timer. An easy level of stealth.

Good luck.

Edit which isn't actually an edit: Are these fans the Antec tricools? I haven't used them but I believe they get 12v all the time and the speed control is something in it's sytem. I notice on your specs the input voltages don't seem to make sense?

 

[maryjohn]

.24 plus .28 is what scrub? Am I reading this wrong? It's .52 amps. And it probably spikes higher.

My deltas are rated 2.45, but my 5 amp supply can't get them to 12v.

 

[ScrubNinja]

You are reading it wrong, yes. I think so anyway. The intake fan is running at medium speed, so it's .2 + .28 (the amps for different speeds are noted)

I gotta go to bed now but, say wut? So your 12v 5 amp supply won't run the Delta at 12v speed? Why not?

 

[maryjohn]

I gotta go to bed now but, say wut? So your 12v 5 amp supply won't run the Delta at 12v speed? Why not?

because the actual peak draw I need to get there is over 6 amps. The literature gives the constant draw - 2.45a, but the reality (and the number on the sticker) is higher. Some kind of safety catch kicks in, and even if I turn up the knob it won't budge.

I wonder how many other companies publish the peak, not the constant draw, and how much that usually differs from reality. In any case, I'm glad i got that PSU, it is teaching me things about current.

Paranoid I know you are "thinking about running slow or medium", but I think I will strongly advise having more options rather than fewer. I guess variable supply will not give you more options, but you need the amps for sure. I would go to a secondhand place, maybe buy an old video console, something like that.

 

[kcbudz31]

If you put a big capacitor across your output terminals, you'll be able to charge up the cap by turning on the PSU, then you connect the fan - it'll draw its spike current off the capacitor's charge, and then the PSU will power it stably from there.

No idea how big a cap you'd use - it depends on the actual current spike and how long it lasts.

Also, if you have compressed air handy you can spin the fan up and then turn on your PSU, that should remove most of that startup load spike.

 

[maryjohn]

If you put a big capacitor across your output terminals, you'll be able to charge up the cap by turning on the PSU, then you connect the fan - it'll draw its spike current off the capacitor's charge, and then the PSU will power it stably from there.

No idea how big a cap you'd use - it depends on the actual current spike and how long it lasts.

Also, if you have compressed air handy you can spin the fan up and then turn on your PSU, that should remove most of that startup load spike.

Oh sweet! thanks man!

 

[Paranoid one]

Hi MJ and Scrubs! Thanks for the input!
MJ: I have a mid tower case. I also have four 23watt cfl's. but was planning on using 3 (maybe 4 if temps don't skyrocket.)

Scrubs: yes these are the antec tri-cool fans. So yeah i'll take your advise on this one. I don't have room for error. And I just don't have time to go out and all+ radio shack is like 60 minute drive from my house.
Just a little "q".
On the chart it says the fans have a max amp usage. As I've read, fans only draw the amps they need.
Or does the adapter give out that "x" amount of amps to the fan? I think the 1st one is correct but I'm not sure about this.

You may even want to hook the intake up to the 300ma, and the exhaust fan up to the 500ma. Then it's impossible to overload if switched wrong, and you have the added benefit of being able to turn your intake fan off at lights out, automatically via the timer. An easy level of stealth.

Edit which isn't actually an edit: Are these fans the Antec tricools? I haven't used them but I believe they get 12v all the time and the speed control is something in it's sytem. I notice on your specs the input voltages don't seem to make sense?

About that last part... No clue what that is about. I just copied the little specs table from the users guide.

 

[maryjohn]

my adjustable psu has a digital readout, and I can adjust both amps and volts.

Even if I turn the amps all the way up, the devices only ever take what they want, and the number on the readout stays the same. So just don't turn them up to max, and they should draw less than .5a. If you find you need to turn them up, you will need a stronger power source.

are you going to be scrubbing with the exhaust fan?

 

[Paranoid one]

are you going to be scrubbing with the exhaust fan?

Yes I'm. I've made my own scrubber with superior air flow/ stops (atleast 85-95% of the smell). If you ever seen the Bose commercial on what's makes a Bose speakers superior to all the other ones on the market. But mine is in a cup shape rather than a speaker shape.
Once I get a decent digital camara I'll make a diy thread on it. And I'm sure it has superior air flow because I've been working on it for 2months now perfecting it.

 

[ScrubNinja]

KC, thanks although wouldn't that be tricky to implement in a system we want to be automatic?

Mj, I'm so confused - at least I'm honest. I have no idea but I suspect your issues are related to your particular supply. Most people have the opposite problem in that their underamped supply runs their fans, but it's not safe.

Both my Deltas seem to be stickered with the max/peak - higher amps than the website (and other pics of the stickers) lists. If Delta lists you as 2.45a and a 5a supply doesn't start it up, then that means the peak draw figure on your sticker is >5a?

Para, cool, I like round grows if that's what you mean. Let us know how you go.

 

[maryjohn]

oh sorry scrub, I forgot to remind I have two of those deltas hooked up. And they will start, but then the limiter or whatever on the psu kicks in, keeping the voltage below 12, or to be exact, at exactly the level at which it can still supply sufficient amps. Delta lists them at 2.45, but the sticker says otherwise.

Remember, I was able to fry a single delta with this psu.

I would not quite call this a problem. I am running at 5 volts. I may turn it up to 9 on a very hot day.

 

[ScrubNinja]

Wow, and that's with 500w? I would love to get one but I think it's just a bit too loud for what I want at minimum. You said it's like a desktop computer volume on 5v right?

 

[maryjohn]

Wow, and that's with 500w? I would love to get one but I think it's just a bit too loud for what I want at minimum. You said it's like a desktop computer volume on 5v right?

It's with a 5 amp psu. I would have to get off my ass to get the watts, and then you would get them at 120v AC.

about like a computer, yeah. But some comps are noisier than others. This would be on the noisy end. Like my old alienware was.

It makes me more comfortable to know I can crank it up to jet engine levels on a hot day. But at the highest i can crank it, these babies sound like a vacuum cleaner.

 

[ScrubNinja]

Sorry dude, I meant 500w of CFLs. I think you said you weren't using all 500w yet or something?

 

[Paranoid one]

No clue on what you mean with a "round grow" but I was talking about the scrubber earlier being cup shaped.