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Solder Fume Extractor
I had never used a solder fume extractor before, but I have been good at blowing the smoke/folder fumes away from my face for over forty years of frequent soldering. There are not too expensive solder fume extractors for the home lab available in the internet, but DIY is not only for saving money.

Since things can change and I wanted to play a bit, I have built myself a solder fume extractor, which works with a
strong fan, a PIR sensor, an Arduino (pro micro) and an USB lamp (since you can never have enough light in the lab, especially, when the eyes get older (than the mind).

Beside a fan with as much through put as possible, I wanted to switch it on with a PIR sensor. PIR sensors are nice, but they require some self calibration time (about 60 seconds) when they are powered up. A time, that I certainly do not want to wait before I start working. This resulted in the need of a micro controller. Since Arduinos are fairly cheap controller boards, I decided for a "pro micro", which is nice and small.

The power supply is a
12V wall wart AC-adaptor. The pro micro and the USB-lamp require a 5V supply, so I decided to use a cheap DC/DC converter from ebay. The USB-lamp might have a higher supply current and I did not want to overheat a linear regulator (such as a7805).

The fan offers PWM control of the RPM. I did not know, whether is it good or not, but anyway, I have built in a
potentiometer on the front panel and a PWM output on the micro controller perf board.

To somehow filter the solder fumes, I ordered an
activated carbon mat from ebay. The mats slow down the air flow and I don't know, how effective they are, but I keep them. I have seen commercially available solder fume extractors for the home lab, that also use carbon filters, so I keep mine.

To hold the carbon mats, I have made a
frame from some sheet of acrylic, which also holds the fan. I might consider to construct such a frame for 3D printing, but that is a priority 13 project. Instead of acrylic, some plywood might also be sufficient.

I have wired up the whole thing in a plastic enclosure with a metal cover/filter in front of the filter and an ordinary filter cover in the back.

Here is the schematic of the perf board:

And here is the Arduino Sketch: