DIY USB Powered Fume Extractor From an Old Computer

If you're anything like me, you might have a rather large supply of old electronics that you just can't bring yourself to throw away because, "It might come in handy someday..." Well, today might just be that day. It was for me, at least. After being told by my wife (repeatedly) that I needed to do something about all the fumes from soldering, I decided to heed her advice and get a fume extractor. Fortunately, with my stockpile of old, semi-functioning electronics, I had the materials I needed to build one myself.

For this project, all you'll need is:

• An old computer (or just a computer case fan)
• An old USB cord (bonus points if only the USB Type-A end of the cord is functioning)
• A screwdriver
• A soldering iron
• Solder
• Heat shrink or electrical tape

First, make sure the computer has been powered off for a good 24 hours, just to ensure it has had plenty of time to discharge. Then, open it up. Usually, you can just remove a couple of the screws on the back and slide one of the panels on the side of the computer back.

Lay the computer on its side, and locate a fan. Usually, there is an easily accessible fan attached to the back of the case. Go ahead and follow the wires from fan back to the motherboard, and pull the wires from the motherboard.

Remove the screws holding the fan to the chassis of the computer. Occasionally, there will be clips or something similar that are holding the fan in place even when all the screws are gone. In that case, squeeze the clips together or break them off.

Cut the fan wires and the USB cable. Try and cut it so as to leave yourself as much wire as you can (or care to have). On the fan, this means cutting as far from the actual fan itself as possible. On the USB cable, this means cutting as far from the USB Type-A end as possible (The larger, more rectangular end of the cable that you'll want to plug into your computer).

In case you're unfamiliar with how to splice wires together, you might watch this video from Make. While we don't need to solder this connector to NASA specifications (and my soldering job certainly doesn't fit to them exactly), it is a rather informative video that will teach you how to splice the wires well enough to hold together over time.

In any case, the red wire on the fan is typically power, the black is ground, and the yellow is usually feedback. For splicing the wires, red goes to red and black goes to black. In this guide, we won't be using the feedback, so you can leave it cut or solder it with one of the other wires. If you're using heat shrink, don't forget to slide it on BEFORE you start soldering the wires together. Definitely haven't made that mistake before...

NOTE: Occasionally, you'll find a 4-pin fan or a fan with differently colored wires. For a four pin fan, you'll also have to solder the PWM/Control wire (usually the blue wire) to the power wire. For a fan with different colored wires, you'll want to look up a pinout or a wiring guide in order to try and figure out which is power and which is ground.

If using heat shrink, now is the time to slide the heat shrink over your solder joint. If you have a heat gun, you can use that and it will work best. If you don't, you can take your soldering iron, clean the solder off it, and lightly run it up and down the heat shrink to get it to close around the solder joint.

If using electrical tape, carefully wrap each wire in electrical tape so that the power and ground will not touch.

Plug it in and test it!

If you want, there are several potential extensions of this project. For example, you can add a switch to turn it off without unplugging it from your power source. You could also 3D print an enclosure for it to make it a little more presentable or a little more flexible. You could also add a potentiometer to one of the 4-wire fans to add speed control! There are plenty of things you can do, so make it your own project!