Will 5k Potentiometer Be Enough to Handle 5 PC Fans?

No.

Is it the resistance or watts?

No, you can't; these fans have an internal driver to create a rotating magnetic field.

In the cases that they are speed controlled, they are actually running at lower duty cycle but at the same voltage; so no, you can't just use a pot or you'll burn it, but wait, after smoking the pot, well, everything seems to be running slower doesn't it ?

I don't want it to burn while spinning slower. I saw this lad doing it with a potentiometer so i though i could do it too with 5 fans.

Check it again, the fan goes from 0 to full speed in a narrow spot, after 3 quarters of a turn have passed.

Not a good way to do it, but if you're ok with that, just make sure that the sum of all 5 fans rated watts won't exced the pot's wattage.

I don't understand about the pot wattage. What is the pot wattage? Maybe maximum wattage a single molex can handle? Because i do plan on connecting them all (or bottom 2 on one molex and upper 3 on another molex).

That is nice little thing, if all else fails i will do this.

Sorry Fred, we must have been posting at the same time with the same idea. I got interrupted with a phone call GA from me!

I'd love to know your reasoning how this kid used a 500 ohm multiple watt, chassis mounted rheostat to control a fan while you plan on using a half watt 5000 ohm potentiometer to control five fans.

If you try to do this, keep a fire extinguisher nearby.

Thanks for the tip, but as i said i clearly don't understand a thing about potentiometers or generally electronic engineering.

I doubt it, but you did not provide enough information to make that call.

You need to know what voltage that the fans operate and what current or wattage they draw.

Knowing that you can use the formulas I=E/R and Pw=I•V to solve your question.

You probably should also lookup parallel and series circuits to understand how to apply those formulas.

All this assumes that the fans run on DC voltage and the speed can be controlled by voltage.

Lastly, it can get a little more complicated than simple DC circuit analysis because you also have an inductive property to the motors that induces a slight surge in current upon startup.

The problem is that i still did not buy those fans, but they will most likely be generic ones, most cheapest ones that's why i would want them on lower voltage to reduce speed when full speed isn't needed. They will be definitely 12v as they are PC fans. What is pot? :D I do not know a single thing about electrical engineering except for a basic power circuit.

My recommendation would be to use a 50 ohm 10 watt rheostat to control your fans if you are looking to get by with only one component.

Or if you want them slower but still running sufficiently to cool things move them from the 12 volt source to the 5 volt power. That's what I have done on my computers to cut down on fan noise.

A rheostat is too big for a small PCB from what i can see on a picture.

Unfortunately the laws of physics say how big the resistive control device has to be not you.

The PC fans I have draw about .8 amps on 12 volts so five of them would draw about 4 amps total. Given a 12 volt input and a good 6 volt drop the potentiometer or rheostat will have to dissipate 6 x 2 = 12 watts being at half voltage the fans will draw about half the amps which puts my first estimates of using a 50 ohm 10 watt rheostat off a bit.

Given that what I would recomend is a ~5 ohm 15+ watt rheostat if your fans are of similar power as mine.

The second more efficient option would be to use a variable output DC - DC buck converter to give you the variable output voltage that would control your fans.

You said "A rheostat is too big for a small PCB from what i can see on a picture."

But due to the "cheap" way you want to do things, that will be the safest way....it was really good advice!

The pot YOU want to use (as many have already said), is far too small (power wise) to handle probably even one fan.

But also, you have neglected to find out the wattage of the fans and to tell us, so that is not a given!!

Furthermore, some fans do not like to be driven with a lower voltage, they will simply stall, get hot and melt/catch fire....so what you are trying to do is far from good EVEN if the total wattage of the fans is below that of the pot!!! Which I seriously doubt.

You even forgot to mention how many wires the fans have and what the color of those wires are.....

You are heading for an expensive to fix "accident" with your lack of knowledge and even understanding for all the help you have already been given by many others here, all good advice!

The best recommendation I an give you is to give up and go and do something useful that you both understand and are trained for and leave fans alone!!!

I don't know how much wattage or amps they require as i didn't buy them yet. I already said that. They will be 2 wire fans, if i buy 4 wire ones i wouldn't need controllers anyways if i connect it to a motherboard :D

I will leave this, because i don't want to fry something like you said, but instead i would try to make a fan splitter beacuse i need one. Like this http://www.pccasegear.com/images/PH-81097-thumb.jpg

I appreciate everyone's advices, you convinced me not to burn my PC into a crisp

Thanks :)

The splitter appears to need 3 pin fans......

Use one of these:

Router Speed Control Dial

Item #43060

Sale: $19.99

I'm sorry but that seems to be too big and expensive, as i said i'm going towards the least expensive method. Can a fan controller like this be done cheaper that it actually is?

Shirley you jest.

<unsubscribe>

Probably not. Those things are so cheap now why don't you buy one of those?

I think I have 2 or 3 of them sitting around my shop!

Your better off building multi- stage controller with thermistors with about a 3°F differential that turns each fan on and off as needed. It's a lot cheaper than replacing a power supply or the whole computer. Once the magic smoke appears, there's no putting it back in And you might even learn a few new things

Otherwise, your handle will fit your fate

You mean something like a temperature sensor? When a certain temperature is present fans start to spin? If so then how would i make it, any circuit schematics or diagram (or whatever it is called)?

Yup, and their fairly cheap to build. http://www.electroschematics.com/4788/temperature-controlled-dc-fan/ Or Google " fan temperature control schematic"

Since you want to spend practically no money, why do you want to control the fan speed anyway? Is it noise?

There is no simple, inexpensive solution that will meet your needs in this case, the fans cannot be controlled simply and safely with a variable resistor. Even adding switches to turn on and off fans is likely going to be too expensive an option.

My advice is to turn up the headphone volume and live with the extra noise. That costs nothing.

I don't use headphones. I will probably have to shove my PC into the closet if it gets too noisy.

What area / country do you live in?

Those PC fan controllers are super cheap. Why are you trying to re-invent the wheel?

Click here

Kingwin FPX-001 Four Channel Turn Knob Multi-Fan Controller

$16.99 In stockLED Indicator for Power On/Off. Control 4 Sets of Fans. Fit 3.5" Bay.Buy online from Fry's Electronics

I live in Bosnia and Herzegovina and cheapest one i could find online is from Akasa i think which is 80BAM (around $60 or so)

Okay 80BAM for the fan controller.

How much are you spending on the fans?

How much did/are you spending on the computer?

You may be acting, to use the British slang, 'Penny wise and Pound foolish,' risking the damage/destruction of a thousand BAM worth of computer equipment to save 80BAM in parts.

Well turn up the speakers then. I was under the assumption that you were trying to overclock an old PC for gaming, hence the game sound would cover up the fan noise.

Why all the extra fans anyway?

I will have 4 of them. 4 fans isn't something i would call extra, just i like to have a good airflow as i'm designing a PC case optimized for good airflow.

As I pointed out earlier running12 volt computer fans off the 5 volt power rails quiets them down considerably but still allows for reasonable air movement.

Zero cost involved.

I just pull the covers off and clean it out once and a while....

No, no, no, no. You're supposed to conspicuously consume by letting your hair, dead skin cells, clothing fibers and other debris pack up all of the moving parts and heat paths so the least expensive parts in your electronics fail before the newest software renders the whole design obsolete.

For that to happen, you need to scratch your scalp and skin all day long over the PC, but still chances are the new software appears before you clog it.

The cheapest possible controller for fans of any sort, that usually works, but needs to be tested before doing it, is to use for instance 12 volt fans, two at a time, with a double pole changeover switch to switch them between serial and parallel operation. Or simply wire them serially for low speed all the time, no switch needed.

You have 5 fans, you need a 6th one.....you can only do (try) this in pairs.

Some fans will not start at what is half voltage, cheap ones for example!!! Ball bearing fans may need some running at 12 volts, to run in, before being used at the lower voltage.

Some AC fans will start and run at a lower speed with a diode in series, one that you can bridge with a switch for full speed.

Many years ago I modified the mains plug for my simple soldering iron with a diode and a switch, so that I could have it partially warmed up, but not burning hot while working on PCBs, a flip of the switch, full voltage applied and it was melting hot in seconds instead of minutes....

Nowadays I have a fast temperature controlled one......but its not that much better really.....

why not just switch some of the fans with switches?

Perhaps I don't grasp what it is you are attempting, but if five fans running at full speed are too much then perhaps fewer fans?

Alternately, individual switching that turns on more fans as the temperature increases? Could be manual or thermostatically controlled. My graphics card has fans that do this.

In my experience these fans last longer and run better if left at full speed so again I am not sure what it is you wish to accomplish.

Are you adding these fans to a computer? And you don't want to spend the money on a proper speed controller for them?

Save yourself the trouble, take the computer on a boat trip, and then toss it in the deep ocean.

Your attempts to do things 'on the cheap' for an expensive piece of equipment will just destroy the equipment in the long run.

If you want to learn Electronics, start with simple circuits, like the old Heathkit or Radio Shack kits. I know those companies are long gone, but there are newer companies making 'beginner electronics kits' now, just too many for me to remember all the names. The point is to start with simple, inexpensive bits to learn the 'rules' about electronics and make your mistakes when they won't cost you a lot in ruined parts. Once you know more, then you can move up to more complex stuff, building on the knowledge gained from the simpler stuff.

Education is much like Mt. Fuji. Everyone can see the top, but it's meaningless to simply have someone fly you there in a helicopter. The only way to make the summit mean something is to climb the mountain yourself, find your Own Path. You bay follow someone else for part of it, your path may cross with others, or run parallel to them without meeting, but the path you take is the only one that matters, because it is Your Path. (For those who are wondering, I use the same analogy when talking abut success or failure with 5S/Six Sigma/Lean manufacturing. There's no cookie-cutter approach to any of those, no shortcuts, for a company to make them work, they have to 'climb the mountain' themselves, developing the 5S/6 Sig/Lean system that will work for them along the journey. The companies that fail are trying to take a helicopter to the top, or be carried up all the way by someone else. They didn't find Their Own Path, they took Someone Else's path, and didn't learn what they would have if they made their own journey, so the plan they use won't work for their company.)

I wonder if that is a good course of action.

I have no idea how old or passionate this person may be, but if they have a sincere innate curiosity to try to solve a problem that is outside their domain of knowledge and an honest interest in learning something new, why would you stand in their way?

I would rather try pointing out the path to wisdom and see if they are willing to follow it before I would deep six their aspirations.

Well said! GA from me.

Sorry if i offended you somehow but that is why i came here to post a question, so i can get some help.

Thank you for the apology but one was not needed.

Next time that you ask for help, pay close attention to the questions you are asked to answer. How you answer the questions usually determines how and if somebody can help you.

I know that you didn't know any better but the control of a motor, even a simple PC fan, is more complicated than one would think. As such it is a bad choice to start learning about electricity.

LOL!!

GA

The OP is REALLY difficult to help!!! HIS PROBLEM!!

I'm sorry, did I fail to point to the path of wisdom? Did I not tell the OP about 'making the journey up Mt. Fuji?Did I not suggest the OP start with simpler, less expensive, less risky projects, such as the modern equivalent of Heathkits?

At the risk of pointing out flaws in others, I believe you may have stopped reading my post after my hyperbolic comment about how his idea would damage the equipment he was going to test it on. You might have noticed I tend to use hyperbole a lot, I only exaggerate a million times a post, but every single time is to drive home a point I feel is too important for subtlety.

I know we're all busy as hack, except for those members who are among the retired, and we don't always have time to read whole posts, however, I suggest you at least skim through my 'wall of text' posts before responding, the second paragraph may show a tonal change to indicate the first paragraph was the 'attention getter' joke or the 'Stop! don't do it *THAT* way.' warning before the real 'meat' of the message.

Point taken. I apologize.

Apology accepted, but not required. We're all here to help, and we each do so in our own way. Okay, we're here to help AND to pick on Anonymous Poster #1 when he tosses out a REALLY stupid question as the start of a thread.

Although, to be fair, our comments are nothing compared to when Anonymous Poster #2 steps up and SERIOUSLY rips into AP#1. You'd think AP#2 has an agenda against AP#1, or else AP#2 is just a malicious sociopath with Multiple Personality Disorder.

And why does it seem like I can never look either of those two up on the member index to see where else they've posted on the forum, it's like they're hiding from me somehow.

(It feels like I've stretched that joke out to Seinfeldian proportions, I'm actively fighting the urge to type "And what's the deal with airline food?" ...and so much for trying to fight the urge....)

"Apology accepted, but not required."

What do you mean not required? I'm going to argue that one! ;-)

Not required because I did not take offense at your reply, so from where I stand (sit?) there was nothing to apologize for.

Or was my refusal to take offense somehow offensive to you? If so, then I apologize, if not, then you can go take a flying leap. ;)

I'm working on a flight control right now. Does that count? ;)

No, this is what i liked to do as a small kid, make boats, lights etc. Now i do it sometimes for hobby and you are right i shouldn't do anything risky such as blowing my components up and causing fire. I'm 18 years old but i won't go to electrical engineering school, i'm going for IT. Still a lot to learn. Thanks for commenting.

Just because you're going into IT does not mean you have to stop with the 'electronics tinkering.' while a computer that needs five fans for cooling would be in trouble if the fans malfunctioned, you could make a small 'desk fan' that drew its power from a USB port to cool yourself off on hot days, or more likely, to blow that important scrap of paper off your desk RIGHT when you needed to read it⁽¹⁾, and you'd learn something fun and important from the experience⁽²⁾. Most computer building these days is assembling pre-built components and loading pre-made drivers, but don't let the label of 'IT person' limit you to just hooking up and maintaining networks. Learn a little about everything, and you'll find you're not only a more interesting person at parties, but you'll have a better self-appreciation when you see something new and realize that you already know how the parts that make it up work, and from that, you understand how it works as a whole.

And in closing, welcome to CR4, and you can drop that 'noob' title, a 'noop' would have continued with the poorly planned project despite advice to the contrary. You've already shown wisdom in realizing a mistake before it became an expensive mistake. To continue my 'climbing Mt. Fuji' analogy, I would be happy to point out which paths I feel would be more helpful or more pleasing for you, all you need to do is ask. I cannot climb your path for you, but I can help guide you away from some cliffs and pitfalls as you continue your Journey.

Notes:

1. You're familiar with Murphy's Law, right? 'Anything that can go wrong, will.'
2. In that particular case, you'd learn that paperweights are your friend when there's a fan on the desk.
   

If someone could close the thread because i have given up on making this without any knowledge of electronics. Thanks to all for advising me how noob i am at this field :D
Greetings.