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1 fe_smoke2.jpg
A fume extractor uses an activated carbon filter and fan to remove the smoke, and noxious fumes, created from soldering. The average price of a small hobby version is about $100, this one will run you about $10. This fume extractor will not be as effective as a larger one, but it is better than nothing, and extremely portable. Remember, always work in a well-ventilated area.

Parts you need:

(1) 7812 – Voltage regulator
(1) Candy tin
(1) Switch
(1) 40 mm case fan
(2) 9-Volt batteries
(2) “Cheap” 9V battery connectors (see step 2 & 3)
(2) Pieces of screen
(1) Piece of activated carbon filter
Some heat shrink tubing
A few inches of Wire
Rosin core solder
Miscellaneous screws and washers
Paint (optional)

Tools you need:

Soldering iron
Dremel with cutoff wheel
Drill & small drill-bits
Fine tip marker
Various Screwdrivers
Wire cutters
Safety glasses

Step 1 : Build the circuit

circuit-final.jpg

I decided that that a quick mock-up might be a good idea. I am glad I did. At first, I thought that running the case fan off of just (1) 9-Volt would provide adequate power. In the end I decided that 12 volts “sucked” better, and in this case it’s a good thing.

The final circuit uses a simple switch, (2) 9 volt batteries, a 40mm case fan, and a 7812 voltage regulator. The 7812 takes voltage from the (2) 9-Volts that are wired in series and steps the voltage down from 18-Volts to 12-Volts, which is what the fan requires.

Step 2 : Solder components
3 fe_soldering.jpg
Notice the battery connectors; they are the flexible vinyl version, not the hard plastic type. This allows them to easily fit in the case.
2 fe_soldered_up.jpg
This is a very simple circuit. Solder it according to the diagram, making sure to attach the component leads to the 7812 properly. Don’t forget to use heat shrink tubing on the connections, this is in a metal box…..metal conducts electricity!

Step 3 : Make sure it all fits
4 fe_allfits.jpg
Everything can be stuffed into the tin, but make sure you use the cheap kind of 9 volt connectors. The cheap ones are the kind made of vinyl, not rigid plastic. The difference in thickness is minimal, but it is enough to stop you from putting both 9 volts in the case.Step 4 : Cut & Mark the openings (Wear Safety Glasses!)
5 fe_cutting.jpg
I used a marker and a paper template for the fan openings. The openings are 35mm square. I marked the opening for the switch at the same time. Then I cut all the openings with a Dremel tool and cutoff wheel (Wear safety glasses!). Next I marked and drilled the (2) holes for the switch screws and (1) hole for the regulator.
6 fe_allcut.jpg
After you cut the first fan hole, close the box and use the 35 mm square paper template to align the second hole. Just “eyeball” the placement. In reality it isn’t that crucial to have them exact. There is room for error.

Step 5 : Paint
7 fe_painted.jpg
I decided to paint the tin this time, unlike my plain RuntyBoost. I chose a nice red Krylon paint. I hot glued a scrap piece of wood to the inside, so I could hold it while I spray painted it. Two quick coats and I think it looks good. Krylon paint is fairly toxic and flammable, so paint it outside and away from everything!

Step 6 : Attach the regulator and switch
8 fe_assembly.jpg
First screw in the 7812 using some washers and a screw to space it from the side of the tin. I used a #6-32 screw and (1) washers to keep it from the edge, but you can use anything that fits. The screws and washer will also act as a heat sink. Finally, screw in the switch

Step 7 : Add the screens and filter

fe-sandwich.jpg

Here you can see the screen-filter-fan-screen sandwich. The screens are 50 mm square & the filter is 40mm square. You can buy replacement filters for the commercial extractors at a reasonable price. Next, just hot glue, or epoxy, the corners of the screens down, and sandwich the filter and fan in-between. Compression will ultimately hold it all together.

Step 8 : Admire your work
11 fe_finished.jpg

10 fe_use3.jpg

All done! I am happy with how it came out, but it definitely needs some graphics to spruce it up. Any suggestions?
Step 9 : Test
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I have run mine continuously for hours and have had no heat buildup from the 7812 and the fan is still running strong. It seems to work quite well, although it is no replacement for a large fume extractor, it will come in handy for small projects. Remember, follow all safety guidelines when soldering, and work in a well-ventilated room, even if you have a fume extractor.

Marc de Vinck

I’m currently working full time as the Dexter F. Baker Professor of Practice in Creativity in the Masters of Engineering in Technical Entrepreneurship Program at Lehigh University. I’m also an avid product designer, kit maker, author, father, tinkerer, and member of the MAKE Technical Advisory board.


Related

Comments

  1. MC says:

    Good demonstration of how to use a 7812, but 1/3 of the battery power is being turned into heat in the 7812. This raises a number of questions. Would the fan run acceptably on just 9 volts? (No battery power wasted.) Would it be damaged if you gave it 18 volts? (Quite possibly, but we don’t really know, and if not, it would run nice and fast.) Of course, a high-efficiency switching regulator would be too complicated for this type of project. But let’s keep thinking…

    Of course, it’s quite possible the designer tried these things and concluded that the design published here really is the best.

  2. dilldoe.org says:

    forgo the 7812 and use 2AA & one 9V
    1.5V x 2 + 9V =12V

  3. Marc de Vinck says:

    @MC

    9 Volt was not strong enough, I tried it.
    18 Volts seemed too much (but I really don’t know)

  4. Marc de Vinck says:

    @Dill***

    True, or I could use photo batteries that are 12v, but I wanted to make a little project using the 7812. I ran mine for hours and had almost no heat, and the fan still runs strong.

  5. knotlinks says:

    beautiful project, and extremely useful. Much nicer than the comp fan I have hooked up to a computer psu.

  6. Marc de Vinck says:

    @knotlinks

    Thanks! There will more in the future.

    If you happen to make one….Please send me a picture!

  7. jproach says:

    The price of a hobby fume extractor is much cheaper than $100, can move a lot more air, and wouldn’t require one to replace batteries (example: http://www.mcmelectronics.com/product/21-7960).

    but anyway I think this is a very nice presentable package, good for small jobs.

    1. Marc de Vinck says:

      @jproach

      That one is really cheap!

      But the “average” price is still about $100.

  8. Adam P says:

    I scoured the web trying to find a site that explained how to determine what battery power I needed to run a case fan, so I am thrilled to find yours and I have a few questions for you.

    1) About how long will the fan run on the 2 9volt batteries?

    2) Will rechargeable batteries work just as well?

    3) I know it is long, but please bear with me!

    My “project” is I want to create a smart fan…that can sense the temperature and turn on when the temperature drops below the desired temp, and turn off when the temp exceeds the set temp…much like a household thermostat. There are 2 wrinkles to my plan:

    1) Rather than connect the “thermostat” to the house, I want to connect it to a fan, much like the one you have here. This hurdle seems small enough to me. If I used a thermostat or something similar, the electronics and the existing brains would act as my switch and it can manage power to my fan (provided I dont have power conversion problems which you may wish to warn me of).

    2) Any ordinary household thermostat wont do, because the temperatures I want to register are between 100 and 800 degrees farenheit and most household thermostats only register 90~100 degrees F. To overcome this, I considered taking a thermostat from an oven, since it is designed to handle the higher temperatures, and still in many ways acts like a household thermostat in that it can manage the provision of electricity to maintain temperature.

    Do you have any thoughts or suggestions on this? I’m really interested, but I know nothing about engineering and electronics, etc. I just want to find a cheap way to manage the temperature of my BBQ grill by managing airflow. Similar systems online sell for $200+ and I’m hoping to build my own for much less. Can it be done?

    Thanks for your patience and ideas!

  9. Marc de Vinck says:

    @Adam,

    For your purpose, I would run it from (1) 9 volt. I needed more “juice” to get the airflow through the filter, which you don’t need. That will eliminate the need for the 7812 or a switching regulator. Check Google for thermostat circuits, temperature circuits, etc….there are a lot online.

    Rechargeable batteries have a lower nominal voltage. Figure out the circuit prior to making a battery decision. Since space will not be an issue (Heat will!) I would suggest using other types of batteries.

    Good luck, and if you make one…..send us a link so we care share it with our readers.

  10. Lincoln says:

    What’s a good/cheap/easy source for the Activated Carbon filters and the screen?

    Thanks.

  11. Marc de Vinck says:

    @Lincoln

    The screen can be purchased at any craft store (I paid about $2 for enough to make about 50) or Home Depot. Better yet, salvage from anything with a screen or perforated metal.The filter can be found online, (Amazon, any electronics supply stores) look for replacement filters. You can get them really cheap, and 1 filter is enough to make 6 -10 mini fume extractors.

  12. Eli says:

    How about taking apart a 9v and using two extra cells out of it so you get 12v. Just keep the extra 4 for the next time you change the batteries.

  13. Anonymous says:

    Why not run it on a car battery?

    Seriously though, great how-to!

  14. Marc de Vinck says:

    @Eli

    Great idea! – Now try it out and send me an email w/link to pictures!

    @Anonymous

    Car battery? That would be a good idea for a bench version. It certainly would last a long time!

  15. Maltedfalcon says:

    Cant you just use a 12v wall wart?

    1. Marc de Vinck says:

      You sure can, but the portability is really handy.

  16. BigIg says:

    I Have a bunch of 120mm case fans, I imagine that, although it would be bigger, it would probably work better. Now to find a box that fits it nicely.

    Sure, I’ll be loosing the portability factor, since I’ll probably rub it off a AC-DC adapter anyway, but I’m not worried about portablity, I just need to stop soldering without one of these things!

    1. Marc de Vinck says:

      I’m glad this inspired you to add some safety to your lab.

      I think 1 of your fans would be enough, maybe 2?…..mine is tiny and it works great. If you make one, which I hope you do, send me a link to some pictures!

  17. Sil3ntP8nd8 says:

    How long will the batteries will actually last?

    How about USB powered? Id rather have it be USB powered since i work next to my computer and have the option of using a battery or not. thanks

    1. Marc de Vinck says:

      @Sil3ntP8nd8

      You can calculate the time (roughly) if you know the maH of the batteries and the specs of the fan. (you lose a lot due to heat of the 7812) All I can say is mine lasts a long time!

      I would look for a 5 Volt fan and goggle “usb wires”. You should be able to hook it up fairly easily. The main problem will be a 5 Volt fan may not be strong enough to suck the smoke through the carbon filter. That is why I went with the 12 volt system.

  18. le Cauchemar says:

    Nice Project.
    What about changing the filter?
    Do I have to? After what time?

    1. Marc de Vinck says:

      Thanks! Yes, you do have to change the filter. Luckily, you get about 4 “mini” filters cut from a standard filter size. They end up being really cheap. I change mine when the airflow slows or is “looks” dirty.

  19. benoitespinola says:

    By putting a 12V adapter and a couple of entries (so you can choose the tin’s orientation, you can save a lot of space inside the tin and put a second fan so you have 3 options : none of the fans runing, just one or both… What do you think on this?

    To get it portable you can also make a tinny box where you put your two 9V batteries and your 7812…

    Or you can integrate the 7812 in the main tin so you are shure you always get 12V for the fans….

    1. Marc de Vinck says:

      @benoitespinola

      That’s a great idea!

      My main goal was to make it portable and cheap. Adding a power adapter and second fan increases the cost (a bit) and makes it less portable. However, having a choice of 1-2 fans and different orientations is GREAT!

  20. Joel Smith says:

    I’m having trouble finding the appropriate filter locally. Any tips on sources or links to suppliers?

    1. Marc de Vinck says:

      I am sure you can find them cheaper. I’ll keep looking.

      http://www.amazon.com/Zephyrtronics-Filter-Carbon-Fume-Extractor/dp/B0001A3EU2/ref=sr_1_4?ie=UTF8&s=hi&qid=1229052552&sr=8-4

      Keep in mind, that might be enough to make 10!

      Here is another supplier that sells 5 for $20.

      http://www.zeph.com/zt-4.htm

      There are cheaper sources….I’ll keep looking. I can buy them locally for <$5 a piece.

    2. Aquarium/Fish shop is where I bought 1ft^2 of it for $4. Enough to make several. Now looking for a project for the filter.

  21. Joel Smith says:

    I built the project as originally described here and it’s working great. I found activated carbon filters in the aquarium section of the local pet store, and they seem to do the job.

    I think I’m going to try building a bigger version with a VHS tape case and a bigger fan, and will use the 12V adapter instead of batteries since I already have the portable version now. Has anyone tried a larger version?

    1. Marc de Vinck says:

      @Joel

      That’s great! I would love to see some pictures!!!

      Thanks for the tip on where to get the filters.

    2. Robert says:

      It’s based on a 120mm 12v fan and a RadioShack project box. See my comment below for a picture. I’ll taking more pictures and doing a build write-up on my blog at some point.

      1. @ Robert

        This is great, thanks for posting the pics. Send me an email when you have them all up so I can blog it! Thanks!

  22. cessna928 says:

    I was wondering, what speed difference an LED would make if I added it in series and would I likely have to add an additional resister to keep it from burning out? I’m sure it probably depends on the particular led, but still I thought I’d ask.

  23. Chris says:

    Well there is a fun project! Just so everyone knows you could add 4 LED s in series parallel to the fan or you could put another fan on the outside in stead, also in parallel. Or you could find a 5 volt fan and just wire it the same except the 7812 is a 7805 and the fan is now a 5V fan. also do you guys know how to post an article on the MAKE blog that would be nice to know.

    1. Marc de Vinck says:

      Thanks for the ideas. I like adding LED’s. I am going to have to try that out.

  24. Daniel says:

    Hi, first of all, nice project! Really like the idea.

    I’ve got a question though, I’m not that well versed in electronics and most fans I’ve inspected come with a 3rd (signal) wire, which I assume is used to report the RPM of the fan to the motherboard. Anyway, my question is this:
    Should I rather just cut off that cable and isolate it, or should I just connect it to ground?

    Thanks for any help.

    1. @Daniel

      Try using just the (+) & (-) to be sure you have it right…..then cut the 3rd wire. One last thing, send me some pictures when you are done! I would to share them with our readers.

  25. Robert says:

    I just finished building a larger fume extractor having been inspired by this how to.

    There is a photo of it here: http://www.flickr.com/photos/hooloovoo/3572730410/

    I’ll be posting more photos at a later date.

  26. Pat says:

    Your product has one fatal flaw, activated carbon does not remove all the harmful particulate that solder fumes process. A HEPA filter is required, and is actually the preferred method for filtration of solder fumes if to choose between one of them.

    1. Marc de Vinck says:

      Thanks for the info. The filter I use is cut down from a standard filter that comes with most commercial fume extractors? (At least most of the ones I have come across) I will have to look for a HEPA version.

  27. deepak says:

    where did you get the 40 mm case fan for this project?

  28. sushiman says:

    where did you get the fan?

    1. Marc de Vinck says:

      They are readily available form most electronics/hobby shops that sell components. You can also get them at many online shops. Mine was scavenged from a power supply.

  29. actaruss says:

    hello!
    Very nice project, clapclap :)
    I was wondering if it was possible to replace the 2 big 9v batteries by some flat little batteries like CR2032 (so we’d need 6 pieces) ?

  30. Marc de Vinck says:

    Thanks!

    Yes, technically you could, but they would not last very long. The amp-hour of those batteries under load would be fairly low.

  31. actaruss says:

    hi again,
    *excuse my english but I am french :)
    Instead of puting this project into a candy box, I wanf to put it in a ‘normal’ enclosure (the ones used for electronic projects).
    I have 2 questions for you my friend, please give me some advices:

    - how could you make the enclosure stand by itself (do you know if some little tripods exist, or enclosure with integrated tripod?)

    - will it be simple to cut the opening in those kind of enclosures?

    Thank you very much for your precisous help :)

    1. Marc de Vinck says:

      Actaruss

      Your English is a lot better than my French! :)

      I would recommend you use a plastic enclosure. It is easy to cut and can stand on it’s own. No tripod is necessary.

      You can drill a series of holes instead of cutting an opening.

      Hope this helps!

  32. actaruss says:

    hey MArc it is a very good idea, drilling holes instead of a grid, that’s what I’m going to do and see if it extracts fume well. Have a nice evening

    1. Marc de Vinck says:

      Make sure to send me some pictures so I can post them!

  33. actaruss says:

    hello it’s me again :)
    concerning the fan, are you sure that it will “extract” the fume and not “push” it? because fans in general blow the air and don’t aspire it… I think I’m wrong but could you please explain me if the orientation of the fan is important for example?
    thanks a lot

    1. Marc de Vinck says:

      You have 2 solutions for a fan that blows the wrong way.

      Switch the wires of the fan, or turn the fume extractor around.

      Either will work fine!

  34. actaruss says:

    hello Marc,
    do you know if it is possible to use a bigger fan which would be powered by the two 9v batteries? For example a 50×50 or 60×60.
    Then maybe the voltage regulator would not be necessary ?
    Thanks for the quality of your answers :)

    1. Marc de Vinck says:

      Sure! Use a 18V fan if you have one. Even a slightly higher voltage fan should be OK. If it’s bigger, use a larger enclosure…..use what you have. Make sure to send me some pics if you make one. Thanks!

  35. actaruss says:

    yes I promise for the photos :)
    I found many 12V fans which are bigger than 40×40 (even 110mm fans), so I can take one of them and keep the 7812 ?

  36. Twain says:

    hi Marc,
    Thanks for your great idea !
    I project to realize a fume extractor with this 3 fans board:
    http://img512.imageshack.us/img512/4843/fansu.jpg
    It works on 12V so I think I could adapt your circuit by replacing your 40mm fan by these 3 fans.
    But as you can see on the photo, there are many wires.. and I am a litle bit lost…
    I can see 2 white connectors, do you think I can cut the second to remove it, in order to use only the red and black wires, not the yellow?
    And do you think the two 9v batteries with the voltage regulator will be strong enough to feed the 3 fans?
    Thank you much for your help !

  37. justin says:

    im going to try to a LED and a potenimeter to the circuit
    the pot is going to be for how fast the fan spins and maybe add the LED to the pot so the LED dimmers to tell u the fan is going slower :D:D maybe hard :O

  38. mpechner says:

    I went to halted in Santa Clara and picked up various fans:
    A 93MM 12V .22A 5 blade fan: worked perfectly with a 2 inch distance. Sort of worked with a 3 inch distance and fairly useless at 4 inches.

    A 55MM 12V 0.09A 7 blade fan. 2 Inches, 3+ not good.

    A 55MM 18V .13A 11blade. 2 inches again.

    Looks like it just does not matter much.

    I think I’ll try the professional version at work and see what happens when $40+ are spent on a fan.

    I’ll post another comment when I try it out.

    I’ve seen the weller. It is $50 with a 12 inch fan and runs on 110. It might be worth to just stop screwing around. Or buy a larger 110V fan from halted.

    These 2.5 to 3.5 inch fans can move just so much air volume.

    1. Marc de Vinck says:

      Thanks for the info.

      Try scavenging a fan from one of the 1000′s of computers and electronics in the trash! They’re free!

      This project is great for “on the go” soldering and can be made for < $3…..if you can buy a full size one for $50, grab it!

  39. Nick says:

    here is one for just under $40 which includes shipping, the candy tin version just seems too small to be effective:

    http://www.mpja.com/prodinfo.asp?number=15166+TL

  40. Nicks Lakers says:

    Beautiful make. Bravo sir. I admire your handiwork as well as intuition. I plan on making one for myself and more for anyone else who wants one of these handy and almost-too-stylish-for-a-tool device.

  41. Anonymous says:

    Thanks all is very well.

  42. Anonymous says:

    Thanks all is very well.

  43. Anonymous says:

    Thanks all is very well done.

  44. Anonymous says:

    Thanks all is very well done.

  45. Beeb Potvin says:

    This is a really cool project to do. I did as my first soldering project and I’m 11.

  46. DES says:

    I like this project, instructions could be a bit more detailed though.

    Unfortunately I am not having any success with this one! I hooked everything up as the diagram shows, turned the switch, the fan starts spinning and then it powers down… I turn the switch off and wait a second, turn it back on and the fan spins, for a very short time and stops again!

    I cut out the 7812 and ran it off just one 9V. It worked great! I hooked it back up to the 7812 and the two 9V version, still having the power issue. I got mine as a kit from Jameco.

    Any input would be much appreciated. It seems like the 7812 is bad or something?

    Thanks!

  47. Aron Black says:

    How would you add a LED light into the circuit?

  48. Oli says:

    What would you do if your fan has 3 connections?

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