How to make a USB powered desktop fan

Make a USB-Powered Desktop Fan

A case fan from an unused PC, repurposed as a personal cooling device

On a hot summer day, a cool breeze blowing on your face can feel refreshing, rejuvenating. But heck, the office ceiling fan is on the other side of the room... as is the window. What to do?

If you (or the IT guy) have got an old computer case lying in a closet, you can salvage the case fan and turn it into a personal USB-powered desk fan. When it's not blowing air onto your face, you can use it to cool your mad-hot typing fingers.

And if you don't have any old PC cases, you can pick up a case fan for as cheap as $6. As for the other parts -- you've probably got them all lying around your house or the office, too.

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Contents  [hide] 1 What you'll need 2 Cutting the Cable 3 Make the Connection 4 Plug it In 5 Tweaks and Adjustments

What you'll need

• An old (or new) case fan, preferably 5V or 9V, but 12V can work too
• USB cable
• Soldering iron
• Solder
• Wire cutters
• Electrical tape
• Scissors (optional)

Cutting the Cable

Near one end of the USB (the one you intend to plug into the fan, not the computer), cut the cord. You can toss the end you just cut off. If you want to make the USB cable shorter so it better fits on your desk, you can trim some of the cable from the middle.

Strip the plastic insulation off (about an inch or more) to reveal the wires within. Isolate or cut off any white or green wires -- we don't need those. Strip the red and black wires.

Your finished cable should look like this. We tinned the wires, you don't have to do that

Make the Connection

If your case fan is new, it may have a three-pin connector at the end of its wires. You can tin the ledes from the USB cable (coat the bare wire with a thin layer of solder, which aids connectivity) and then connect black wire to black wire, red wire to red wire, through the connector. Don't worry about the ground wire on the fan (it's usually yellow). In fact, you can just snip it off.

If you salvaged your case fan from an old computer or don't have a connector, just solder the USB cable directly to the fan's power wires -- solder the black wires together and the red wires together. You can cover the exposed solder points with electrical tape.

This is what the wires look like just soldered together

Plug it In

Just plug the USB cable into any computer USB port to turn it on.

Tweaks and Adjustments

USB cables deliver 5V, so a 5V fan is best. But 5V fans are uncommon in modern PCs, and you'll probably only find one if you're salvaging a fan from an ancient desktop. You can sometimes find lower-voltage fans in laptop PCs, but otherwise, you're probably stuck with a 9V or, most commonly, a 12V fan.

If you're using a 12V fan, it will still work, but the fan will just spin with a very low RPM. Ours worked, but blew only gently (probably not at its full 4500 RPM potential).

You can fix that by adding a switching regulator to your setup, a pretty simple circuit that will boost the voltage from 5 to 12V. This is a component that you'll have to solder together yourself, but it's a simple circuit and you can find everything you need in your local electronics supply store.

If you'd like your fan to blow at an angle (up at your gorgeous face, perhaps?), you can also use a coat hanger or similar thick wire to create a stand for your fan.

This page was last modified 19:38, 27 July 2011 by howto_admin.