Solder Fume Extractor

Soldering is one of the key activities in electronics, but are you soldering safely?

The fumes released by the solder are not healthy at all; therefore, one should always solder in a well ventilated area, or even better, while using a fume extractor. However, commercial fume extractors can be quite expensive. It's basically a fan that pulls the fumes through a carbon filter, so why not make our own?

It's a very simple and cheap build, and something that everyone should own. To make it even easier to use, we'll power it via USB. That means it could also be powered by a USB battery bank. Let's build it!

• Computer fan
• Fan grill x2
• Box/case (size depending on fan diameter)
• M4 screws & nuts OR M5 screws
• Active carbon filter (for aquariums)
• USB cable or 12V power adapter
• Boost converter (only when using USB)

The fan & fan grills can easily be taken from an old PC. The carbon filter can be found at a pet supply center or simply online. The boost converter can be bought on ebay, amazon, or even aliexpress; it steps up 5V to 12V.
The case I used is a simple hard plastic container, but it was of the perfect size.

Total cost < €10

Now onto building the fume extractor; we'll start by making the necessary modifications to the case.

Start by putting the fan grill on the lid of the box, and trace around it. Also mark where the holes need to be drilled.
Cut out the shape with a rotary tool (Dremel) or an X-acto knife and drill the 4 holes.
When that's done, draw a circle on the bottom of the container (the size of your fan) and cut it out.
Furthermore, drill a hole in the corner of the box, and feed the USB/power cable through. Also, tie a nut in the wire.

If you have a tap & die set, we need to make a little modification to the fan. Take an M5 tap, and tap the holes that are already present on the fan. Now the M5 screws can easily thread in the fan, and no nuts are needed. You could also try using the screws themselves to make the threads. Otherwise, use M4 screws and nuts.

Now, we'll solder the boost converter to the fan. Make sure the USB/power wire is fed through the case and solder the red and black USB wires to the 'IN' markings. Attach a multimeter to the 'OUT' pins, and turn the potentiometer (on the boost converter) until you get 12V. When you're sure the boost converter outputs 12V, solder the red and black fan wires from the fan to the 'OUT' markings. I glued the USB wire in place, because the wires were very fragile. If desired, a switch could be added. At this point, it's a good idea to test the fan.
For a nice explanation on how boost converters work, take a look here.

The final step is the assembly, which is quite straightforward.

Start by pushing the screws through the lid of the container. Next, add one fan grill, the carbon filter, and the other fan grill. Now, thread the screws into the fan, or secure with nuts.

The carbon filter should be thin enough, so the airflow is not too weak. Mine was about 3 cm thick, so I cut it in half with a knife. This is the part that adsorbs the fumes and should sometimes be replaced.

Finally, the case can be closed. When using a metal box, the boost converter should be isolated with a bit of tape. Otherwise, just push it in the case.

Plug in the USB cable, and the fan should start spinning. When soldering, the fumes will be dragged into the carbon filter and adsorbed, keeping the air fresh and clean!

Happy soldering!