If you solder (and we know you do), you absolutely need ventilation, even for that lead-free stuff. Fortunately, [tinyboatproductions] has gotten into air quality lately and is here to help you with their snappy 3D printed air-filtering design.
At the heart of this build is a 120 mm notoriously-quiet Noctua fan coupled with a carbon filter. It does what you’d think — position the fan the right way and it sucks the air through the filter, which catches all those nasty particles.
The only problem is that the Noctua uses PWM, so there’s no governing it with a just potentiometer. To get around this, [tinyboatproductions] introduced an Arduino Nano and a buck converter, both of which were admittedly a bit overkill. Now the speed can be controlled with a pot.
Once control of the fan was sorted, [tinyboatproductions] decide to add an OLED display to show the fan speed and power condition, which is a nice touch. Be sure to check out the build video after the break.
If this doesn’t have quite enough features for you, here’s one that’s battery powered.
“The only problem is that the Noctua uses PWM, so there’s no governing it with a just potentiometer.”
That doesn’t even make any sense. There is no magic within the fan that makes it not work, if you’re controlling the voltage via a potentiometer or if you e.g. use PWM to pulse the power-line, instead of the PWM-line. You can perfectly well use these fans with plain voltage-control, no problem — using the PWM-line is not a requirement.
As far as I know all PC fan are brushless motor with a built in controller of sorts, so trying to control them via the voltage may not work at all, though I’d expect it work reasonably well most of the time. But still you are much more likely to get the desired quiet operation treating a PWM by design fan as a PWM fan, just dropping the voltage will likely to lead to more variable rotation rates which you may well hear (if it works at all at the low voltage required for the speed you wanted).
Only the PWM-fans have a chip in them and it’s just a manufacturer-specific PWM-chip, really. No real magic there. And yes, you can use PWM-fans perfectly well with e.g. older motherboards with only DC-fan headers, it’ll just somewhat less precise; I take it you’ve never tried?
Just as an additional nitpick: as for getting really low fan-speeds, PWM-signal isn’t a panacea, either. Typical consumer-oriented PC PWM-fans usually have a cutoff at around 10% – 15% speed, but in my experience, driving those fans via DC-control tends to go slightly lower.
Oh I’ve done it, but results are far from perfect or predictable really. Some fan really won’t take to being run much lower than the expected voltage – the only time I’ve really had to do it those specific fans had to be running nearly flat out to run properly at all! Though I’ve played with others that behaved better. And running smoothly but slowly against resistance like the dense fins of your tower cooler or in this case a filter even if they do spin normally in free air is another problem entirely.
The point being these PWM designed fan motors are not certain to just work properly on low voltage as they do have some electronics inside that may expect to run only around the nominal voltage!
Huh. I’ll have to admit to never having encountered such fans myself; all the PWM-fans I have (some Corsairs, Phanteks, Noctua etc.) work just fine with basic DC-control and none of them have required them to be run near the nominal voltage. I mostly use Noctuas and they certainly haven’t had any problems, whatsoever.
Very low PWM frequencies give the fan a periodic “kick” that keeps it revolving, where plain DC voltage control would stop, but that results in an annoying whine from the motor. Higher PWM frequencies above 20 kHz are really no different from DC unless you’re driving a proper PWM fan by the proper input, and only then if the fan is smart enough to have speed control logic instead of just chopping the drive current.
I haven’t noticed them stall in DC mode, but maybe all my motherboards have prevented that. I wasn’t paying attention, and when I got a separate speed controller to DIY an air filter, it was a fancy 4-pin type.
exactly. there are motherboards that offer option to dc voltage control for pwm fans and those who play with PC fans knows you can easily lower the voltage to slow down the fan even without the pwm wire.
The PWM-signal is there really for two reasons: finer-grain control, like you may not get quite the same range of control or as precise control without it, and to shift the responsibility from the motherboard to the fan.
Standard comment with these builds:
Nice build! As for the carbon filter, apparently they are best at filtering odor, if you want to get rid of (possible harmfull) particles, a HEPA filter is the better way to go; see; https://www.sentryair.com/blog/industry-applications/soldering/comparing-solder-fume-extractors-its-all-about-the-filter/
Thanks for the useful link!
The solutions seem very expensive, though.
A cheaper and pretty simple option is this:
https://www.instructables.com/Proven-and-Effective-HEPA-Air-Filter/
“If you solder (and we know you do), you absolutely need ventilation, even for that lead-free stuff.”
The hazard from solder fumes is not from lead. The fumes contain no lead at all.
The hazard is from the burned organic materials from the flux.
I’d say you most especially need a fume extractor for lead-free solder since the flux for that stuff is usually nastier than the flux for solder with lead.
I agree, flux compositions are not the same for all solder alloys. Traditional Sn60Pb40 usually contains 2..2½% “mildly activated rosin” with its distinctive smell – at least the stuff from reputable brands like Kester, Stannol and Felder. Lead-free solder needs a more aggressive magic soup and more of it, up to 3½%. Some Sn99.5Cu0.5 industrial solder wires are real stinkers that can make you cough and puke instantly.
I’ve noticed a “tin fever” from unleaded solder as well when working without a fume extractor. Spend a day soldering and the next morning you wake up with a stuffy nose and general malaise.
Using a fan with low static pressure for the opposite task is not exactly clever…
+1
Indeed. These thin carbon filter + PC fan builds are pretty common.. and I have bought one of them and built one of them; they just don’t do much. They do circulate the air though, which is already a big help as many of the particles will land somewhere else than in your lungs, and have time to aggregate to less harmful and larger clumps.
The thin carbon filter is really not doing much. I made a fume extractor out of PC fan and IKEA lamp arm a few years ago. The fan alone cannot generate enough sucking power. In the end, I have to add another inline fan to improve extraction.
https://www.printables.com/model/374832-fume-extractor-with-led-illumination
No one to mention a 555 generating a nice PWM signal and a pot to adjust the duty cycle ?
Well, I felt it was so obvious that it’d be pointless to even mention it.
I remain unconvinced that these activated carbon filters are adequate, I’ll keep using my flexible air duct with a channel ventilator to the outside.
After i built a sen55 particulate sensor for my lab i stopped soldering untill i got a fume extraction system. I thought i was fine with a carbon filter, but it turns out all it did was spreading it out even more. You easily get pm-10 levels around a few houndred from simple rework job and up to 3-400 from extensive soldering.
I got a yinhua rework station with the little suction nozzle over the soldering tip. I thought it was a gimmick but it seems to work really well. I use a couple of carbon filter discs stacked in top of each other to increase their surface area, instead of the single one it uses as standard. The little ball gauge on the base station doesn’t tell you the actual suction pressure, but it’s enough to let know know when the filter is “full” andd restricting flow. The filter seems to load up after a couple of hours, I was amazed how much smoke and crap it is removing, that was previously going right in my face.