In this instructable I will show you how to make a very powerful fume extractor from a car A/C Heater air blower supplied by an ATX computer power supply.
If you already made a fume extractor from a computer fan before or you own a genuine fume extractor, you are probably aware that it's not very efficient and that most of the smoke will go in the room and in your face instead of going trough the fan into a filter or a duct leading outside. That's why I finally decided to build this powerful fume extractor to eliminate any of those toxic fumes to gather in my shop.
It's very powerful and yet not too noisy, has two speed settings and can optionally be used with a foot switch. Whether it's to get rid of toxic fumes from your soldering iron or to simply get rid of any unwanted smoke or vapors, this is the blower you want. :)
Note that It is not filtering the air and just blowing it outside, although you can use a carbon filter to filter the fumes and blowing the air outside would no longer be necessary unless used for other non filterable chemical vapors such as ozone generated by high voltage arcs.
Step 1: Things You'll Need:
Here's a list of the things you'll need for this project.
- ATX Computer power supply with ideally at least 10 Amps on the 3.3V and 5V rails
- Car A/C Heater air blower
- Two SPDT (single pole double throw) Power switches
- 80mm or so fan guard
- Round metal box to use as the case for the blower
- Dryer exhaust air duct or any other air duct you have lying around
- Foot switch (optional)
- Hot glue, a LOT of it
- Rosin core solder and a soldering iron
- Electrical tape or heat shrink tubing (optional)
Note that the speed setting switch needs to be able to take up to 5A, although the on/off power switch can be a low power switch and won't burn up.
For the power supply I highly recommend using an ATX one as figuring out the wiring configuration of older non-ATX power supplies can be tricky but I do it all the time, It's just a matter of searching on the internet and doing tests with your multimeter. Another thing is as they are very old they sometime needs a minimum load to stay on so yeah, go with an ATX power supply unless you can't get one and have decent electronic engineering knowledge.
Step 2: Test to Make Sure Everything Is Working Properly
To test the blower I simply tighten it in the vice using a piece of cloth to make sure I wouldn't damage it and connected it to the 5 Volt rail on of the power supply in series with my multimeter set to Amps.
The reason I used the 5 Volt rail is because at 12 Volts it draws about 10 Amps and I didn't want to waste a good power supply on this project and it was getting a bit too noisy and over-powered, like industrial grade air blowers.
The 3.3 Volt rail is a good choice to add a slower speed setting or if you're looking for something more quiet.
Update: I added the option to get a lower speed using the 3.3V because at 5V the blower was still quite noisy. the circuit diagram with a foot switch and without one can be found later in this Instructable.
Step 3: Hack the Power Supply
WARNING: Computer power supplies have two huge capacitors inside of them that can sometimes hold a charge of up to 120-240V that can easily give you an hazardous electrical shock! Caution should be taken.
First, remove the screws and take the cover off. You can now short the heatsinks to the case with a screw driver to make sure they are not holding any charges. (they really rarely do)Now you can remove the screws holding the circuit board and carefully pull it out to gain access to the back of it. Test the two huge capacitors to make sure they are not holding any charges with your multimeter and if they do, discharge them by connecting a 1 Meg ohm resistor or a light bulb with the proper voltage rating to their pins for 10-15 seconds.
Now that you're done with the safety precautions what you want to do is remove all the cables you don't want and just keep what's necessary, you'll need two grounds, one 5v, one 3.3V and the PS-ON cable. Use the ATX power supply wire color code table as a reference.
Don't put the power supply back together just yet unless you don't plan on painting it. :)
Step 4: Cut the Blower Case
First, cut a hole in the bottom of the metal box just big enough for the blower to fit, you don't want to cut too much or you won't be able to glue the blower to the box later on. You then need to make a hole in the center of the box's lid for the intake, I made mine about 80mm of diameter because I happened to have a fan guard of that size. (I stole it from the power supply itself) Now cut a square hole on the side of the box, that's going to be the exhaust.
Now we can finally start painting everything.
Step 5: Prepare the Power Supply to Be Painted
The power supply that I used was impressively easy to completely remove from the case but most of them usually requires the wires to the mains connector to be desoldered so you may want to consider leaving it the way it is if that's the case. (pun intended)
Step 6: Paint Everything
I used a primer as I wanted the paint to be more scratch resistant but a good "paint+primer" should do the job if you let it dry for a day before you assemble it or it might end up full of scratches once you're done.
Once the power supply case is dry, you can put it back together and proceed to the next step.
Step 7: Install the Fan Guard to the Lid
Nothing much to say here. I just drilled four holes and screwed the fan guard to the lid. :)
Step 8: Glue the Blower to the Power Supply
Okay, I know hot glue is probably the worst solution I could find, using a metal strap screwed to the power supply would surely help. But hey! I've been using it for eight months and it's still holding nicely. :D
Take note of how I placed the motor cooling hose, it has to be where you want your exhaust so if you want it on the side make sure the hose is on the side.
Step 9: Wire It All Up
I did a simple schematic on how it needs to be connected because I used a non-ATX power supply and the wiring color code is different and the pictures are from when it only had the high speed mode and had a foot switch with an extra useless switch that I ended up using for the two speed option. :)
Here I used a small plastic box I had to mount the switches using a Dremel to cut the openings while it was secured in the vice. You can just glue the switches directly on the side of the blower case later on or mount them in any ways that you can possibly find. :)
Step 10: Glue the Blower Case to the Blower
Now that you're done wiring everything it's finally time to glue the blower case to the blower. I used hot glue for doing this, I'm sure there are some better alternatives but that's what I used. Make sure that the blower is rotating freely and not rubbing against the casing. Once the blower case is glued to the blower you can glue the case lid in place and all that is left to do is add the exhaust air duct!
Step 11: Glue the Exhaust Air Duct
Glue the air duct to the exhaust on the blower case making sure that the motor cooling hose is going inside as shown on the second picture.
Here I used a dryer air duct but you can pretty much use any air duct you have lying around.
Step 12: Final Thoughts
After using this blower for about eight months, I'm still very satisfied with the results. It can get quite annoying at the high speed setting but for how efficient it is to get rid of all the fumes, I can't really complain. :)
Adding an LED lamp to it would be a great addition if you don't have much lighting in your shop, soldering in a dark place is a pretty bad idea.
And as always, Hope you found this Instructable helpful and interesting. Also make sure to follow me to see more of my projects!