How do I get around the 120mm Fan power issue?

I was wanting to make a laptop cooler and i have a few ideas; 1) Use a mains cable (12v jobby) and connect the 120mm fan to it 2) Battery pack (what batteries and is this feasible?) 3) USB (im pretty sure a 12v fan cannot be powered by a 5v usb socket) What are the requirements to power a 120mm fan i.e. which is the most feasible? Thanks :)

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anarchysk88 years ago
rich_moe8 years ago
120mm Fans are usually 12VDC, so a wall-wart plug-in transformer connected to the fan is more than likely your answer. Batteries wouldn't last long (and are rather expensive). A 12VDC fan will run on 5VDC, but the power draw and minimal air movement make it more trouble than it's worth.
Garbit (author)  rich_moe8 years ago
make sure the mA of power source you use is higher than the mA of the fan. most 120 mm fans take way more than 50 mA
Garbit (author)  110100101108 years ago
Quick question, if i wanted to extend the cable of the mains power adapter what wire would i need to use?
on the high volt side use cable made for sufficient voltage on the 12 V side any cable with plastic isolation is ok
Garbit (author)  110100101108 years ago
you guys are really helpful :) thanks alot!
rich_moe Garbit8 years ago
I would say that approximately the same type of wire would be safe. Solder the wires together, or use a crimp splace, and then insulate.
rich_moe Garbit8 years ago
Somewhere on that fan is a little sticker or some indication of voltage, power consumption, rpm/rate of flow. Find out how much the power draw is, and get a mains transformer that has the power output rating of at leat that much plus 10% to 20%. I'm going to guess that the fan came from a computer case, since most fans for case cooling are about 120mm in size. The little sticker is normally on the motor; sometimes on the case of the fan. If you find that the mains transformer that you had in mind can put out the power necessary, then stripping the wire off the power supply and matching them colour-wise will work just fine, but will run continuously when plugged in...