Absolutely Fuming

Dion Smith

Issue 9, March 2018

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Fume extraction is an important safety consideration when soldering - second only to “don’t touch the hot bits”. Dion came up with an ingenious solution to this problem, and we wanted to know more!

Many of us have used leaded solder for years. It’s probably what makes our Editor-In-Chief a little (some would say...) strange. Even with the increase in lead-free soldering, there’s still fumes from rosin and such, which are still better sucked away than inhaled.

This is an excellent project! How long have you been tinkering with electronics, Dion?

I’ve been doing electronics for about nine months now. I started with a Freetronics Experimenter’s Kit for Arduino with my eight-year-old daughter and my seven-year-old son. Since then we have done a few electronics kits, like the Sparkfun Weevil Eye, and the Jaycar Arduino Game Machine, and I am currently working through “Electronic Circuits for the Evil Genius” book and projects by Dave Cutcher, which I highly recommend for anyone else who’s starting out.

That’s fantastic. You’re never too old or too young to start playing with electronics, and it’s great that you’ve found a mutual love for it with your kids! This fume extractor is an awesome creation. Was your first idea to build it into an ATX PSU case, or was that a secondary consideration after deciding to build the extractor?

My original idea was just to use something to get the smoke away while soldering. I had a bit of a look around to see what was available and found a few extraction fans, but I thought I could build something similar using an old computer case fan I had. So I wired it up using a small solderless breadboard, jumper wires, and a universal multi-voltage charger.

I used it like that for a few weeks, and it worked okay but the fan needed to be very close to whatever I was soldering in order for it to work effectively. So I put a message out to my friends on Facebook to see what I could find. I ended up with about four non-working computers and some extra PSUs. One of the PSUs no longer worked as a power supply, but the fan worked great, so I took everything out except the fan, picked up a pack of extractor fan filters from Jaycar, and that was it.

Until a few weeks later, while working on a night light for my daughter, which runs off a 9V adaptor. I found myself constantly swapping the extraction fan and her night light with the one remaining power point I had for testing.

fume extractor
The fume extraction is surprisingly powerful.

I searched the internet for similar projects with extraction fans and a small benchtop power supply, but no luck. I did come across a small DIY power supply with 12V, 9V and 5V voltage regulators, which had a voltage meter attached and ran off an unregulated 9V power supply.

Using this as a starting point, I wired everything together on a solderless breadboard and that was the 12V, 9V and 5V covered! Next was the 3.3V output, which came from a LM3940 voltage regulator.

I started to draw a rough schematic on paper, but it quickly became a mess due to various changes and additions, so back to the internet I went, to see what options there were for designing schematics. After looking at the tutorials on the Core Electronics website, I decided to teach myself Eagle. Although daunting at first, I quickly found my way around (thanks to a few instructional videos). I even went as far as making a few elements of my own to add, such as the fan and the voltage meter.

With all the components running on the breadboard it was time to start putting it all together inside the PSU case. The fan and filter went in first, then the voltage meter and four-way switch. The switch itself was a bit too wide, so I used the Dremel to cut some off each side, but that caused a problem with some of the connectors touching the outside of the case. So to avoid the possibility of a short, I opened up the switch and removed the unnecessary connections - problem solved! The last bits went in without any issues, so then all that was left to do was clean up some of the rust from the inside, patch up any holes, and give it a fresh coat of paint.

The other advantage of using a multi-voltage charger, and the fact that the 12V selection on the unit has no restrictions, means that I can run any of the following voltages: 3V, 3.3V (via the LM3940) 4V, 5V, 6V, 7V, 9V, and 12V.


“Just casually taught yourself Eagle” eh? That’s quite a commitment but worthwhile! We’re glad to hear you had success with it. What filter material have you installed into the unit?

The filter is from a pack of replacement filters for the Jaycar’s Solder Fume Extractor Cat. No. TS1581. I had to cut them down a bit to fit, but they work great. The smoke goes in the front and air comes out the top.

That’s awesome - makes replacing filters in your own unit easy down the road too. Is the extraction fan itself the original from the ATX PSU, or did you put a new one in?

The fan is the original. I just used some longer bolts to fit through the filter, I also added some alloy mesh that I had in the shed to keep the filter material from rubbing on the fan.

You’ve covered the old IEC mains connector with a blank. Did you 3D print it? It looks great!

I’d love to get a 3D printer! It’s the original IEC connector; I just cut the bottom section off with my Dremel, glued some fine mesh over the hole, and added a little skull icon to match the one I added to the fan grill on the front. I did consider welding the hole over, but this way if I decide to add something else later on - like an LED testing connection - then I can use that spot.

The completed Fume Extractor.

Simple but effective! It looks great and that’s some good forward-planning to keep the space easily used too. How did you go about designing the circuit? Did you have a particular set of requirements, or did you just determine what would be useful?

A little of both. I knew I needed 12V for the fan and for an output (so I could add a second fan if needed). I also needed 9V for the “Electronic Circuits for the Evil Genius” projects, which are all 9V. I also needed 5V and 3.3V for my various Arduino boards. Because the fan was so quiet, and with the filter in front of it, I also needed something to let me know the fan was going, so I added a few LEDs, and the rest I just made up as I went along!

I think we call that “procedural engineering”! Okay, we don’t - but maybe we should! Your schematic shows the 5V regulator feeding the 3.3V regulator. This is probably a better choice than bringing it down from the 12V supply! Was that your first choice?

When I was looking into what to use to get a 3.3V output, the LM3940 specs in the Jaycar catalogue say the Vin is between 4.5V and 5.5V, so I went with that. I also modified one of the heat sinks from the original PSU circuit board, I straightened it out in a bench vice, and drilled some extra ventilation holes using a piece of computer tower as a template.

inside the case
Putting everything inside the case.

Nice recycling work! How have you enjoyed using it since it was finished?

It’s been great! I use it every time I use my soldering iron. It’s easy to use, the fan is nice and quiet, and it’s small enough to stay on my desk.

Always good when you’re working on projects - persistent noises can become a big distraction (it also helps keep the peace if your man cave is located inside the house!). What would you do differently if you were to start this project again from scratch with the knowledge you have now?

I would probably go with a bit bigger fan, add variable voltage, and a USB port or two for charging.

Oh yes - USB would be handy. Sounds great for a V2.0! What other exciting projects are you working on at the moment?

I have a few projects on my ever-growing to-do list - like a 1977 Soundic Pong era sports game! I need to figure out what’s wrong with it and try and fix it. Also, my kids want me to teach them programming, so I will have to learn that as well; but first, I want to finish the projects in my Evil Genius book.

Fantastic - sounds like you have a lot of great fun coming up with your future projects, for yourself and your kids! Good luck with it all, Dion!

Dion Smith

Dion Smith

Data Entry-maker and Website Designer.