Activated Carbon Air Filter

Computer fan
Activated Carbon
Glue
Window screen
pantyhose
Modeler's plywood
Basswood or balsa
12 volt AC/DC converter

If you have enough modeler's plywood, then you can make the frame out of that, but to save money, I chose to glue my frame together with some balsa wood I had. I had everything but the activated carbon, which you can purchase at pet stores, already at my house.


The purifier works by drawing air through the carbon and forcing it out through the top. The picture below is a cutaway view. The carbon surrounds the purifier on four walls with the fan on the top. The large surface area allows the air to pass through slowly which cleans the air much better.

This part is critical since it is what keeps your filter from falling apart, so cut and glue well. For the edges of the walls, I used 1/4x1/4 inch strip of balsa. To support the middle, I used 1/8x1/4 inch strip of balsa. Next, make 4 of both the inside and outside walls. You may need to cut some small squares of paper to stick in the corners for extra support.

After the walls dry, lay the window screen out on wax paper. Apply a thin strip of glue to one side of each wall and place onto the window screen. The wax paper will keep the glue, which will run through the screen, from sticking to your table.

After the glue dries, cut each wall away from the sheet of window screen.

Next, cut a 45 degree angle in two sides of the wall so that the four outside and four inside walls can be joined to each other. Make sure that the window screen is on the outside of the square. In the end, you should have two squares with four walls covered and two left open (for the top and bottom of the filter).

Now that you have the two frames made, you can put everything together. But before you do this, make sure you slide pantyhose over both frames. This will keep the smaller bits of carbon from falling out.

Now, take the bottom part of the filter and glue the frames to it.

While that dries, clean the carbon. During shipping, small bits of dust will fall off. Clean it by placing it in a colander and running water through it. Let it dry and pour it into the filter.

Next, once its full, glue the top on. NOTE: the small hole in the top is used for adding or removing activated carbon after the top is glued on. I just put tape over this to keep the carbon from falling out

If all was done correctly, the fan should fit perfectly into the remaining hole in the top of the filter. Glue the fan in place and you now have a finished air filter.

The white tube on the top of the filter is there to help spread the filtered air around the room. To make it, all you have to do it tape together a paper tube that will fit over the fan. The top is made by cutting vertical slits in the tube and overlapping them to make the paper fold over the top and deflect the air into the room.

To turn it on, you take the two computer fan leads and solder them to the 12 volt power supply. If everything works, it will be very hard to hear it running.

Lastly, if you want the filter to emit a fragrance into the room, it is very simple. Place your favorite liquid fragrance into a thin medicine bottle and tape it to the center of the fan. As the air from the fan passes the medicine bottle, it will pull the fragrance out of the bottle and into the air.


Now, the only problem with the filter is that the air emitted has a slight smell of carbon and I am not sure how to get rid of this. Since the fan cannot develop a lot of pressure, forcing the air through another filter would be difficult. If you have ideas then feel free to email me.