Soldering is essential for working with electronics, but the smoke from vaporizing flux isn’t something you want to breathe. CDC: rosin core solder details the risks, but you can reduce the hazards by employing a fume extractor.
Professional fume extractors can be had for hundreds of dollars like the Hakko Soldering Fume Extractor, 120V, ESD Safe. These devices would be worthwhile for someone who solders frequently (such as Louis Rossmann: The tools I use and why I bought them.), but for a casual hobbyist, we can get buy with something cheaper and built ourselves.
The basic idea is to combine a fan with an activated charcoal filter. I used this filter: 1 X Cut-to-Fit Carbon Pad for Air Purifiers. Thanks to YouTube’s GreatScott! for this tip, from: What is worth desoldering from old electronics? || DIY Fume Extractor
Honeywell desk fan
First attempt with a Honeywell HT-900 TurboForce Air Circulator Fan, Black:
As seen in Tools upgrade: Hakko FX-951 soldering iron and more, this is what I was using before to blow the smoke outside a window.
Affixing the cut filter with a rubber band:
This fan did not work so well for this purpose. The fan pulled from the bottom and back, insufficient suction to make any significant difference. The suction was greater without the filter, acceptable to blow away soldering smoke but not filter it. We need to find another way.
Success with a PC Fan
Next up, switched to a spare fan for ventilating personal computers:
I also had a CPU fan, which I removed from the stock heatsink, but instead opted to use this accessory/case fan. This is a 3-pin fan, see Home automation with Raspberry Pi + Homebridge for experiments with reading the tachometer and controlling the speed with PWM, but for our purposes, we only need to power the red and black wires, leaving yellow (tachometer) unconnected. Wrap the fan in the filter:
To power the fan, I first tested with 5 V which I had readily available from the Raspberry Pi, but more juice is desirable for higher speed (but not too much, I already burned out another PC fan by supplying 24 V while writing this! Always check voltage ratings and don’t tempt fate), these fans are rated for 12 V. I instead supplied 10 V using -5 V and +5 V rails from the bipolar power supply built in Surface-mount electronics for hobbyists: easier than you think.
And… it works great:
The smoke is quickly whisked away through the filter into the fan.
Application: unsoldering large components
Unsoldering components with lots of pins requires large amounts of solder and/or solder wick with flux, so it is a good test of our new fume extractor. I decided to tackle these big connectors on a Samsung DVD-HD841 player:
Here’s all the solder wick I used (this brand, if you want the same: MG Chemicals 400 Series #4 Fine Braid Super Wick with RMA Flux, 25' Length x 0.1" Width, Blue, as touched on in Buying from China, I wouldn’t recommend much cheaper solder wick, good quality and quantity of flux is important):
The DVI connector unsoldered without a hitch:
And then the other A/V connectors. With the fume extractor, I was able to salvage these gigantic parts without inhaling too much smoke:
Finally, a last picture of the flowing smoke (TODO: animate this picture):
Conclusions & future enhancements
This is only a quick-and-dirty soldering smoke extractor, it could be improved further. Some ideas: use a dedicated power supply (such as a 12 VDC wall wart, as used by GreatScott, hardwired to the fan), add more fans for more suction, faster fans, more layers of filter, affix more solidly than using a rubber band (GreatScott screwed screws into the filter), adjustable fan speed (but why? you would likely always want maximum speed for greatest fume extraction) via PWM’ing the control pin (4-pin fans) or power (3-pin), measuring the fan speed in RPM via the tachometer (as I did in Home automation with Raspberry Pi + Homebridge, but for this project as well), building an enclosure to properly house the fan and filter, etc.
Nonetheless, for the effort put into it (not much more than a brief evening), this do-it-yourself PC fan + carbon filter fume extractor performs reasonably well and I expect to it to be used for many soldering projects in the future.
Update: New fan, new LM7815-based regulator
The fan in this original article was since a casualty of the short-circuit/overvoltage incident in Exploring ternary logic: TNAND and TAND gates. I removed the PWMFan from the Raspberry Pi with Homebridge from Home automation with Raspberry Pi + Homebridge and repurposed it for the replacement fume extractor fan.
To avoid similar incidents, I used a fixed 15 volt regulator: the 7815 (datasheet: LM78XX / LM78XXA 3-Terminal 1 A Positive Voltage Regulator). Added the recommended bypass capacitors, 0.33 µF (330 nF) on the input (a 0603 surface-mount since that’s all I had), and a 0.1 µF (100 nF = 104, blue drop) on output, as in the typical applications, Figure 6:
Here’s how it looks in practice (the 0603 is on the other side):
Sure enough, given a variable input (about 24 V), the regulated output is very near 12 V (measured 11.99 V):
The final product, connecting the PC fan covered with the carbon filter, to the 12 V regulator, then to a 24 V power adapter connecting to mains:
