# PC FAN ?'s



## lilredwuck (Jul 30, 2008)

looking to put some computer fans in my canopy. I know I will need an ac to dc adapter. How do I know what size to get? Said something about 100 ma should work (just example)
But on my fans it doesn't have the ma anywhere. There are markings on them 0.21A for small fan and 0.18A for the larger one. Umm is it a metric thing? is 1 A = ma and so forth. Explain for me please as this is what I am waiting on


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## KaiserSousay (Nov 2, 2008)

Umm is it a metric thing? is 1 A = ma and so forth. Explain for me please as this is what I am waiting on

1 amp = 1,000 milliamp
0.18 amp = 180 milliamp
0.21 amp = 210 milliamp
For the really lazy,
http://www.onlineconversion.com/electric_current.htm


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## mightyevil (Oct 23, 2008)

lilredwuck said:


> looking to put some computer fans in my canopy. I know I will need an ac to dc adapter. How do I know what size to get? Said something about 100 ma should work (just example)
> But on my fans it doesn't have the ma anywhere. There are markings on them 0.21A for small fan and 0.18A for the larger one. Umm is it a metric thing? is 1 A = ma and so forth. Explain for me please as this is what I am waiting on


You can just get something like this here...

http://www.svc.com/pa-ad-ul-12m-5v.html


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## KaiserSousay (Nov 2, 2008)

mightyevil said:


> You can just get something like this here...
> 
> http://www.svc.com/pa-ad-ul-12m-5v.html


*That shows a 500ma, 5 volt,DC power supply..most fans are 12vdc. *
Quick word about wall wart power supplies. 
The max available amps, as shown on the transformer, is for the length of wire attached. 
What I mean is if you add a longer wire to it, you add more resistance, lowering the max available amps at the end.


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## JALOOS (Sep 6, 2008)

Most computer fans will run anywhere from 5 to 12 volts depending on the speed you want thats a good way to adjust the speed and consiquently the noise they put out. So if you are looking for some air movement but not as much as it moves at 12 volt use a transformer with a lower voltage than 12 volts.

The longer the wire you use shouldn't affect the current of the transformer but the voltage. The longer the wire the more the voltage drop, fairly negligable however and for this purpose not even a factor.

You can also use a transformer with a much higher MA rating (milliamps, and no its not a metric thing) and the fan will only draw what is needed, trick is make sure you don't get one that is rated lower than the fan. A 7.5 volt will give you decent air movement and be fairly quiet as well. I would suggest a transformer that has adjustable voltages and you have the opportunity to adjust the speed/noise if need be.


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## lilredwuck (Jul 30, 2008)

WOW, that is all I can say. Dropped by RadioShack to look how much one was. Thinking under ten I would go ahead and get it. WOW 26.99, Needless to say I still don't have one yet. If I am right any transformer even for say, a cordless phone, would work as long as it pushes enough milliamps and voltage right? I should have a billion different things in the garage. I think I will check today.


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## jrh (Sep 4, 2007)

PMed you with a place I ordered fans from when I needed extra cooling on my aquapod. You can probably find what you want there.


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## fishEH (Sep 15, 2008)

Don't waste the money on one from Radio Shack. Try hitting up a garage sale for some old electronics. Cordless phones, scanners, chargers will all have power supplies that can be used. Just check the voltage. My work holds electronics collections and I pick up old PC fans and power supplies all the time. They work great.


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## KaiserSousay (Nov 2, 2008)

> The longer the wire you use shouldn't affect the current of the transformer but the voltage. The longer the wire the more the voltage drop, fairly negligable however and for this purpose not even a factor.


Wrong...volts would stay constant..amps are what would drop..amps "push" voltage. That is why a car battery is rated in cold cranking amps..ever had a "dead battery", not enough amps to spin the starter(big amp load) but the radio and some lights will still work..all are still 12vdc but there are not enough amps for the starter but enough for the other stuff.
I have another problem with your response. Operating some electronics at wrong voltages can cause serious issues. Fires have been started, and property destroyed.



> WOW 26.99,


You hit a poorly supplied RS..a 110vac to 12vdc transformer should not be more than$10- $15 tops.


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## lilredwuck (Jul 30, 2008)

um so does that mean use a 12volt transformer only? What about the length of cord? I know some people do get away with electrical faults, but only if I could be so lucky. Since it's not a big load would you really tell a difference. It's not like I am pulling 1 gauge wire 10 feet to power a sub. Even then it only dims down when it hit hard. I don't know that's why I ask! I hate always getting conflicting answers!


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## KaiserSousay (Nov 2, 2008)

> I hate always getting conflicting answers!


 :lol: 
Sorry to say, there is no conflict on this, just right and wrong.
I just put 2 strings of 48" led strip lights in my T5 light box. They are 12vdc. I had a [email protected] yard lighting transformer that worked just fine. Transformer was down in the cabinet, but it was rather large, took up too much available space..the hunt was on.
Found a [email protected](.8amps) wall wart, was a 10th of the size. When wired directly to the wart, the lights blaze just fine, but if I splice in 4 feet of wire to hide it in the stand, there are not enough available amps for the lights after it has pushed those 12 volts through the added wire. It would probably work if I went to a much larger gauge wire, less resistance=less amp loss.
Anyway, If I was you I would look for a [email protected] power supply. Would power your presant fans and leave you enough in reserve for additions(within reason).
Shoot, you live in KC, your fan power should only be a phone book away.


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## mightyevil (Oct 23, 2008)

KaiserSousay said:


> mightyevil said:
> 
> 
> > You can just get something like this here...
> ...


Well...I thought that PC fans, Cold cathodes and any of those small PC electronics would only take as much power as they needed and that was it. Guess it doesn't work that way huh?!?!?! I am starting to worry about my moonlights, I bought this to power some cold cathodes...


















Am I gonna burn?!?!?!? I sort of need to know before I burn my family to a crisp.

Amps, Ma, ma, Volts... It all equals alien language to me so I have no idea.

:lol: Sorry for recommending the earlier stuff, I thought it was made for stuff like this! :lol:


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## Rick_Lindsey (Aug 26, 2002)

MightyEvil, as long as the amperage rating of your power supply (which indicates the maximum amperage that power supply can push while still maintaining the voltage indicated) exceeds the amperage draw of your device, you're good to go.

If your cold cathodes are 12V (which I assume they are), and the sum total current draw of any cathodes you have hooked up in parallel (you did hook them in parallel, right?) is less than 2A, you're golden. Assuming of course that you don't splice a high-guage wire in to extend the power cord .

If the device tries to draw more current than the supply is rated for, typically the supply voltage will drop.

Also, if you insert resistance into the path, then as the current draw increases, the voltage on the far side of that resistance will be lower than it is/was at the supply.

Kaiser, I'd be interested to know the guage of the wire you spliced on, since with a reasonably heavy guage wire, I would not expect the extra resistance of 4' of wire to be significant. Oops, I just noticed that you mentioned the same thing in your post .

I suspect, however, that if you took a voltmeter to the end of your newly spliced wire, while it was plugged into the lights (which are blazing less fiercely than normal), that you'd find it was less than 12 volts.

Unfortunately most power supplies are not simple Voltage or Amperage sources once you start to approach their limits. If you are below the amperage limit, though, you can treat a typical power supply as a pure voltage source. The effective resistance of the circuit attached to it will determine the amount of current it draws (that's an oversimplification of course when it comes to active devices, but for the moment the mdoel suffices).

-Rick (the armchair aquarist)


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## boredatwork (Sep 14, 2007)

The idea was right - it was just the wrong product. Here is the correct one:

http://www.pctoys.com/840556029977.html


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## boredatwork (Sep 14, 2007)

And for the record, there is some bad electronics information in this thread so if you are reading through it don't believe any of it.


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## mightyevil (Oct 23, 2008)

So...

These are my cathodes









and like you have seen before, this is my Inverter...









So, if I splice 8' of speaker wire for each cathode I should be okay since speaker wire is a thicker gauge right? Or am I still not getting the point?

This is how my cold cathodes came prewired and I can't tell if they are in parallel or series...


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## aji1217 (Aug 22, 2009)

boredatwork said:


> And for the record, there is some bad electronics information in this thread so if you are reading through it don't believe any of it.


I second that motion. Do your research before trying to convert AC/DC. Not incredibly likely to burn your house down (but still very possible), but you will burn up a fan/light/fingertips real fast if it isn't right.


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## lilredwuck (Jul 30, 2008)

And this is the reason I am moving so slowly (Not really, but blaming others always works). Seriously, if I knew the information I would just be doing it, otherwise I have a billion other things that never get done.


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## JALOOS (Sep 6, 2008)

KaiserSousay said:


> > The longer the wire you use shouldn't affect the current of the transformer but the voltage. The longer the wire the more the voltage drop, fairly negligable however and for this purpose not even a factor.
> 
> 
> Wrong...volts would stay constant..amps are what would drop..amps "push" voltage. That is why a car battery is rated in cold cranking amps..ever had a "dead battery", not enough amps to spin the starter(big amp load) but the radio and some lights will still work..all are still 12vdc but there are not enough amps for the starter but enough for the other stuff.
> ...


I have several problems with your response!

Having taken several electrical course I can say with definate certainty that VOLTAGE drops along the length of a long run of wire. Current is constant and is controlled by the device you are trying to power. Ever run a mini grinder or drill off a 100 foot extension cord for any length of time and wonder why they burn out ? You are forcing them to run on a lower voltage, they bog down, get hot and die. More often because the laquer coating on the wire melts and you suffer a short in the armature windings and arcing brushes. Ever measure the voltage of a dead car battery under load? Think it still reads 12 volts but has no amperage? No the voltage is low enough that the battery cannot push enough current to start the car, but the lower draw items have higher tolerances as far as operating voltages are concerned and thus being low amp draw will still function at that voltage.

A little reading on the subject http://www.altronix.com/index.php?pid=4&note=1

As far as your "...volts would stay constant..amps are what would drop..amps "push" voltage "
DEAD WRONG. Voltage is the measure of "PUSH" as you called it and current is the measure of FLOW, specifically the exchange of free electrons along the wire. Even my kid was taught this in grade 8 shop class. Look up OHM's LAW sometime.

An exerpt from a paper on voltage:
"Voltage is not a characteristic of electric current. It's a common mistake to believe that a current "has a voltage" (and this mistake is probably associated with the 'current electricity' misconception, where people believe that 'current' is a kind of substance that flows). Voltage and current are two independent things. It is easy to create a current which lacks a voltage: just short out an electromagnet coil. It is also easy to create a voltage without a current: flashlight batteries maintain their voltage even when they are sitting on the shelf in the store. Water analogy: Think of water pressure without a flow. That's like voltage alone. Now think of water that's coasting along; a water flow without a pressure. That's like electric current alone."
http://www.eskimo.com/~billb/miscon/voltage.html

As for your statement "Operating some electronics at wrong voltages can cause serious issues." We are talking DC Inductance Fans here, most fan manufactures are giving you the option of pluging in to the 12 volt (yellow wire in comp power supply) or the 5 volt (red wire in comp power supply). Have you ever seen a computer fan control panel ? What do you think they do for adjusting the speed of the fans ? Electronic clutch system ? NO they use reostats or fet based circuits to control the voltage to the fan. Even thermal controllers for these fans do the adjusting of the speeds by reducing the voltage using thermistors, which are a resistor that changes resistance with the temperature.

A little reading on the subject http://www.blackfiveservices.co.uk/fanspeed.shtml


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## lilredwuck (Jul 30, 2008)

Hey, I don't feel like thinking. Can you "dumb" that down to a sentence for me? Like what to buy, lol.


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## JALOOS (Sep 6, 2008)

mightyevil said:


> So...
> 
> These are my cathodes
> 
> ...


I have used several of these in my computers and cars. You can adjust the length of the wires feeding the inverter box the 12 volt but absolutly do not mess with the white wires feeding the tubes themselves. Any attempt at making them any longer will result in the bulbs not firing up at all. These wires carry the equivilant to about 20 thousand volts but very little to no current is drawn thats why the inverters can be as small as they are.

You can add length to the supply line and if it is a larger guage then I wouldn't worry about it at all. These cathodes will let you get away with some voltage drop to the inverter and all it will affect is the brightness of your lights until the drop is too much and they won't light up at all, would take much more than the 8 feet you are adding. In fact there are those that also use reostats to control the voltage to control the brightness.

Once again though DO NOT alter the WHITE wires in any way or the lights will not work at all and soldering them back together will in itself cause a voltage drop (keep in mind we are talking 20,000 volts so a drop is usually substantial) that it will dim the tubes.

Other than that these things are very safe and I have them in 4 computers and all over the place in my car no problems what so ever.

I would also recomend adding a 2 amp fuse in line with that power supply for extra protection in the event that what you intend to draw is more than the rated 2 amps and that the supply doesn't have its own protection. A simple auto style 12 volt 2 amp fuse will do fine.


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## JALOOS (Sep 6, 2008)

lilredwuck said:


> Hey, I don't feel like thinking. Can you "dumb" that down to a sentence for me? Like what to buy, lol.


Dig around in your old transformers. Find a 7.5 to 12 volt dc power supply with a 750ma (milliamp) to 1 Amp output. Get your 2 fans, they are cheap and can be gotten relatively inexpensive or gut them from old computers. Hook 2 up in parrallel (all positive together and all negative together) and your golden. If your fans have a 3rd yellow wire cut it off and don't use it. It is the speed sensor wire for monitoring the fan speed on the computer.

It is not critical to you whether they run full out or slightly slower right? You probably wouldn't notice it anyway. Right? So voltage drop yada yada isn't going to be an issue. I only pointed out that the volume level of these things can be controllled by reducing voltage and if you didn't want to hear them use a lower voltage for them, we all know our tanks put out enough noise anyway right.

Thats it simple as pie.


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## lilredwuck (Jul 30, 2008)

I dug around earlier, but couldn't find exactly what I was looking for. Let me see what I have. I know it says one for in and one for out. Out would be to the fans right. Let me look I'll be back


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## JALOOS (Sep 6, 2008)

lilredwuck said:


> I dug around earlier, but couldn't find exactly what I was looking for. Let me see what I have. I know it says one for in and one for out. Out would be to the fans right. Let me look I'll be back


Right


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## lilredwuck (Jul 30, 2008)

ok here is what I have In- 120v ac 60hz
out-9v ac 200ma
'
In-ac 120v 60hz 4w
out-dc9v200ma

In-ac 120v 60hz 6.5w
out-Dc9v 400ma

in-120v 60hz 55ma
out-dc10v 100ma

In-ac120 v 60 hz 6.5w
out-dc9v 210 ma

In- ac120v 60hz 6w
out-dc 9v 350ma

In-ac 120v 60hz 6.5w
out-dc9v210ma


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## JALOOS (Sep 6, 2008)

Probably run one with

In-ac 120v 60hz 6.5w 
out-Dc9v 400ma

at a reduced speed. Will proably be just right noise wise as well.

Hooker up on the table and give it a whirl.


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## fox (Jun 11, 2009)

I think some of the stuff posted is totally irrevelant to what was asked and causes more confusion than insight to a simple question. Simple translation more volts = spins faster less volts = spins slower and most PC fans will work fine with just .2A. Just read the specs on the fan. A 1600 RPM fan moving ~64CFM of air with a low noise level of 28dBA can be had for under 15 bucks at any micro center.

As long as the fans are not PWM then most PC fans will work flawlessly between 5 - 12V.


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## lilredwuck (Jul 30, 2008)

These are the fans I ripped out of an old emachines t2260 that had the blue screen of death. I took the processor fan and the case fan out. Any use for the heatsink that was attatched to the processor fan? I'll have to hook them up later tonight. 
As for the confusion it's more of a "Am I going to catch something on fire?" more than, "Is this hooked up right, do I have the right equipment?"


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## PfunMo (Jul 30, 2009)

I found after years of reading /responding to electronics questions on rail forums that it is nearly impossible to pass information along on a forum.  One could say the wire is red and start a debate! :lol: I suggest that if you get a fan out of an old PC, the simple thing is to use the power supply also. PC's are getting so cheap that blowing a fan is not going to hurt you much anyway so make it a learning project but just don't try to depend on internet forum info. :roll: It's good for conversation but not much good for your sanity. opcorn:


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## boredatwork (Sep 14, 2007)

You don't need to build anything or know anything about electronics. If you buy a 12V computer fan this is the power supply you want. Its cheap and easy.

http://www.pctoys.com/840556029977.html

I use that power supply with these fans, they are very quiet:

http://www.endpcnoise.com/cgi-bin/e/std ... mm_bw.html

Done.


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## boredatwork (Sep 14, 2007)

Oops, bad link for the fans:

Quiet Case Fans - Nexus 120 mm Real Silent Computer Fan - Black & White with Fan Mounts
http://www.endpcnoise.com/cgi-bin/e/std ... r_fan.html


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