# Ways to power a 3-pin "case fan"



## Matt-Matt

G'day

Not too sure if this is the best place for this, but I figured it would be seeing as it's to do with voltage modifications.

Basically a friends modem/router is getting too hot to run so it will drop packets and cut out, after checking this I noticed that mine runs quite warm, now my idea was to get a smallish fan and stick it on one side of the modem/router and blow the air through it and vent it out the other side. This would probably work rather well, the only problem being is powering the fan.

I had an idea about Power over Ethernet (PoE) but that came to a halt very quickly, I am now trying to find other ways to power a "Case Fan" as to cool down my modem/router combo. The only idea I have is to get a powerpoint-USB adapter and modify a USB cable, I'd have to half the amperage in doing so and I'm not too sure how I'd go about doing that.

Any ideas are appreciated! Cheers


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## compuman145

Yeaaaah,

PoE is an interesting thing however you would need to have a PoE switch which I find is highly unlikely since a 24 port PoE switch retails for around £1000. Even the 8 ports are selling at a few hundred quid.

The likelihood that he's got a PoE switch is slim, your idea I'm afraid, won't work.

Comps


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## Matt-Matt

Quote:


> Originally Posted by *compuman145*
> 
> Yeaaaah,
> PoE is an interesting thing however you would need to have a PoE switch which I find is highly unlikely since a 24 port PoE switch retails for around £1000. Even the 8 ports are selling at a few hundred quid.
> The likelihood that he's got a PoE switch is slim, your idea I'm afraid, won't work.
> Comps


Yeah, just read up more on it.. Wow,

Thanks for that though, +rep

Has anyone else got any ideas on how to power a 3 pin 40mm fan that needs 12v and 0.25A other then a USB adapter?

EDIT: And yes, PoE is rather interesting.


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## kevmatic

What do you mean by a usb adapter? If your router has a USB port, you could just wire up a plug and run the fan off of the 5V from it. Of course, the fan would spin pretty slow, then.

I would take a look at the router's power supply. If its 12v or less, you can just splice into the power lead going into the router; I doubt the power draw from a 40mm fan would overload it. Otherwise, a 12V power brick you have laying around would do the trick.


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## Matt-Matt

Quote:


> Originally Posted by *kevmatic*
> 
> What do you mean by a usb adapter? If your router has a USB port, you could just wire up a plug and run the fan off of the 5V from it. Of course, the fan would spin pretty slow, then.
> I would take a look at the router's power supply. If its 12v or less, you can just splice into the power lead going into the router; I doubt the power draw from a 40mm fan would overload it. Otherwise, a 12V power brick you have laying around would do the trick.


Ah nice, yeah not too keen on modding the power supply cable for the router. What I mean about a USB adapter is something similar to this, they are really cheap and I can get a small USB cable for cheap too. I could also get a Antec Spotcool for it but that wouldn't be as safe and it'd be hard to make a shroud for it.


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## animal0307

You could make a an "adapter" that plugs in between the Power brick and modem. Find a male plug and female plug of the same size and shape as the one for the modem and then wire them together and splice in your fan there.


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## NoiseTemper

You can try this guide http://howto.wired.com/wiki/Make_a_USB-Powered_Desktop_Fan , but it says it'll run really slow. So you'd have to find a fan that when running at 5v volts, pulls out a decent amount of air.

Otherwise get lots of ' 30cm 3 pin fan extension cables' connecting it from your PC to wherever the router is









....I dunno.


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## Juggalo23451

You could get one of these. I have one to power my fans on my receiver.
http://www.newegg.com/Product/Product.aspx?Item=N82E16812123309


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## Matt-Matt

Quote:


> Originally Posted by *Juggalo23451*
> 
> You could get one of these. I have one to power my fans on my receiver.
> http://www.newegg.com/Product/Product.aspx?Item=N82E16812123309


Nice, shame I can't order from the egg though. I'm sure there is something in Australia like that for a decent price and I'll have a look around.
Quote:


> Originally Posted by *NoiseTemper*
> 
> You can try this guide http://howto.wired.com/wiki/Make_a_USB-Powered_Desktop_Fan , but it says it'll run really slow. So you'd have to find a fan that when running at 5v volts, pulls out a decent amount of air.
> Otherwise get lots of ' 30cm 3 pin fan extension cables' connecting it from your PC to wherever the router is
> 
> 
> 
> 
> 
> 
> 
> 
> ....I dunno.


The modem/router is in the loungeroom.. I'm in my bedroom. That's not really possible though, I did think of that








I'm trying to find a way to make it 12v, I know you can get 12v adapters for phones or at least 9v so if I could find one of those.
Quote:


> Originally Posted by *animal0307*
> 
> You could make a an "adapter" that plugs in between the Power brick and modem. Find a male plug and female plug of the same size and shape as the one for the modem and then wire them together and splice in your fan there.


This is a really good idea! I shall investigate this in the next week or so,









+Rep to everyone that can take it,


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## just_nuke_em

Quote:


> Originally Posted by *Matt-Matt*
> 
> Nice, shame I can't order from the egg though. I'm sure there is something in Australia like that for a decent price and I'll have a look around.


1. Find one of these wall transformers/wall warts/AC adapters (whatever you want to call them) that has the correct DC output and amperage. They should be easy to come by at thrift stores or similar places that sell junk.

2. Cut off the plug at the end of the wire.

3. Wire fan directly to it. (the wire with the white stripe is the ground wire)

4. ????

5. Profit!


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## richie_2010

9v battery and box. Or wire it to a 12v line inside the router.


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## Matt-Matt

Quote:


> Originally Posted by *richie_2010*
> 
> 9v battery and box. Or wire it to a 12v line inside the router.


This could be Interesting, I'd have to replace a fair few 9v batteries which aren't cheap however. I was thinking of batteries earlier to be honest,
Quote:


> Originally Posted by *just_nuke_em*
> 
> 1. Find one of these wall transformers/wall warts/AC adapters (whatever you want to call them) that has the correct DC output and amperage. They should be easy to come by at thrift stores or similar places that sell junk.
> 2. Cut off the plug at the end of the wire.
> 3. Wire fan directly to it. (the wire with the white stripe is the ground wire)
> 4. ????
> 5. Profit!


Great idea.. I'm sure to have one sitting around here, would it hurt the fan if the adapter had too many amps/volts? I could use a resistor to lower the voltage but I don't know how to lower amperage.


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## kevmatic

Quote:


> Originally Posted by *Matt-Matt*
> 
> Great idea.. I'm sure to have one sitting around here, would it hurt the fan if the adapter had too many amps/volts? I could use a resistor to lower the voltage but I don't know how to lower amperage.


Haw. I suggest reading up on Ohm's Law. Everyone who works on anything involving wires should.

In short, the things being powered only 'draw' amperage - as much as they need, and no more. You could hook up tiny 12v fan to a 1000-amp car battery and it won't hurt it.

As for the voltage - a resistor would (mostly) work, but may cause problems with the fan starting. I'd just look around till I found an adapter in the 9-12v range and not worry about it. If its a big, older wall wart, though, stay towards 9v, as they have a tendency to produce more voltage than what's on the label.


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## Matt-Matt

Quote:


> Originally Posted by *kevmatic*
> 
> Haw. I suggest reading up on Ohm's Law. Everyone who works on anything involving wires should.
> In short, the things being powered only 'draw' amperage - as much as they need, and no more. You could hook up tiny 12v fan to a 1000-amp car battery and it won't hurt it.
> As for the voltage - a resistor would (mostly) work, but may cause problems with the fan starting. I'd just look around till I found an adapter in the 9-12v range and not worry about it. If its a big, *older wall wart, though, stay towards 9v, as they have a tendency to produce more voltage than what's on the label.*


Cheers, I actually did study electronics 2 years ago I just can't remember much. I'm sure if I read up on it i'd be fine!


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## Fieldsweeper

you could probably use eithernet cable.

strip it for the pos and neg cables and ad a variable resistor (for speed control)

should be enough to run a small PC fan, at least enough for your intended use


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## wochuiniubi

I doubt the power draw from a 40mm fan would overload it. Otherwise, a 12V power brick you have laying around would do the trick


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