Idea for Goggles fan

[Pr1m3]

Hey, I don't know a lot of things about computer hardware, such as fans, so I'm lookin' for someone to help me out with this idea...

I was thinking, my goggles fog up a bunch, apparenty I'm a sufficient furnace to fog up after a bit of playing, so I was wondering about a small computer case/heatsink fan ontop of my goggles (they have little circles for airflow on top...)
Just a small setup ghetto rigged to my goggles...

I was wondering a few things though. Most fans are like a 3 or 4 pin connector, could two of those wires be connected to a battery to manually run it?

And, the fans run on 12V power... If I wired up a 9V to it, would the rpm drop proportionally... (The fan I was looking at is 5000rpm at 12v, would that drop to 3750rpm at 9v?)

I found a fan that supposedly puts out less than 21dba (sound of a completely quiet room i think)
If it was running at 3/4 rpm would it be quieter?
It wouldn't run all the time, just somehow hook up a switch or something so I can turn it on/off if I start to fog up...

Sorry for my poor organization of my thoughts, it all craps out of my brain onto my keyboard and this is what it looks like...

Any ideas suggestions? Flames telling me I should have searched better (cause a did a quick search)?

Let me know, thanks
-Pr1m3

Edit: Good example, inexpensive, decent, and quiet...
Newegg
40mm fans seem to be small enough to be light, and might just work enough to do the job

[Яoman]

A bit big don't you think?

[bigc]

I think 20mm or smaller is what you want. If you look at an electronics parts house you will find these fans that can infact run on one 9v. Back in the day I made one of these for my JT thermal face mask I used in paintball.

[Pr1m3]

Well I do have a removable visor thing that attaches to the goggles, I could fit a 40mm or even a 50mm (with a tiny bit of fileing) on it.
The fan would end up resting around an inch above the little holes for air...
If needed I could get some sheet metal and make a vent thing so the air goes straight into the goggles if need be...

The only question is will a fan made for 12v run off 9v (can't find anywhere around here that would even have a chance of selling a 9v fan)

That's all for now, thanks for the responses
-Pr1m3

[bigc]

I am sure it would however you would likely burn it out quickly.

[kdogg]

I have a semi low cost solution for obtaining a pair of goggles with a fan in them.

First, get on eBay and buy a used pair of ESS Land Ops Striker Military Tactical Goggles. There are a butt load of them on eBay because the military issues these and soldiers are always trying to sell used pairs. I've seen them go for as little as $10 dollars a pair. You find a lot of lots of 5, 6, 12 pair etc on eBay cheap too.

Then contact Smith Optics and, now this is important but lie to them and say you own a pair of Smith Optics snowboard goggles with the fan and the fan died recently. You need to lie because Smith Optics will not sell the fans unless it's as a replacement for a customers existing Smith Optic's brand goggles. They will refuse to sell them to you if you say you are going to install the fan into a pair of ESS goggles.

Anyway the fan Smith Optics uses in there snowboard goggles is the EXACT same unit ESS is putting into there goggles that sell for $130 plus dollars.

The cost of the replacement fan from Smith Optics is only $35 dollars and includes the fan, the wiring, the battery box/control unit.

The final step is to put it all together. The ESS goggles already have the markings in them there you need to cut to install the fan. Just cut it out with an X-Acto knife, pop in the fan and clip the control box on the side head strap.

You now have a pair of ESS Land Ops Striker Turbo Fan or whatever they are called goggles and you didn't pay $130+ dollars.

[Enkidu]

Any 12v computer fan will run just fine off 9 volts. It will run slower than the max speed, but not in any kind of linear relationship. This will not shorten the lifetime of the fan, either.

You will find that a 20mm fan running at 9v will do just fine as a defogger, but you may want to buy a switch so that the fan isn't running continuously and draining your battery.

[Pr1m3]

It would be either a switch, or just wire the battery into a an easily exchangable location, a switch would be best, but im on a very limited budget, unless I get some cash for christmas (limited like 10-15 dollars at most)

[Яoman]

Oh Noes! Not a whole 5cent to a $3 switch!
Radio shack has many electronic doodads and wutnots

{edit}

Here you go. All the switches you will need.
www.radioshack.com/search/index.jsp?kwCatId=&kw=switch&origkw=switch

[Pr1m3]

Talked to my dad, he said a mini/micro switch is good enough, since we are only using less than 1 amp and 9Vs... Better yet, he says he might have it all at home...

Oh, and a 30mm fan will fit, so I will get a higher flow if I need it

Edit: Forgot to mention a 30mm will fit only when i have it offset (since I have to wear full face in some events the clip thing where it clips in takes about 7mm of space, therefore a 30mm offset or 20mm centered... I think if I mount the fan on the right and batt. on the left of the goggles it will look semi-symmetrical...