ELECTRICAL CONNECTIONS DISCLAIMER: If you don't know what you are doing with electricity, find and ask someone who does!  This is a very safe project, but it pays to be careful whenever working with or modifying electrical devices.) NEVER HAVE THE DC POWER ADAPTER PLUGGED INTO THE AC WALL OUTLET WHEN YOU ARE WORKING WITH THE ADAPTER WIRES!!

 

As you can see in the pictures, the materials should be simple to obtain. Use the pictures and this description to guide you in assembling your wind tube.  Once you have all of the listed materials, assembly takes about 10 minutes, depending on whether you decide to hot-glue the sticks to the fan housing.  The fan (wind source) is a common 12-volt DC cooling fan removed from a dead desktop computer.  Its power source will be a 12-volt DC power adapter, salvaged from a scrapped electronic device.  (Never throw away these wall-wart power adapters! They can be used for lots of projects.  Just be careful when matching their power and current characteristics to their intended repurpose.)

 

ASSEMBLY:  First you will need to cut the plastic connector off the end of the fan wires.   Most of these fans have two wires, a red wire and a black wire.  Next, cut the barrel plug off the device-end of the power adapter.  Don't cut the wall plug off the adapter.  Use the wire stripper to strip about three-eighths of an inch of insulation from the ends of the fan wires and the power adapter wires.  Hold the bare end of one of the fan wires and one of the adapter wires together and push them into one of the wire nuts until you feel them stop.  Twist the wire nut clockwise (as you view it from the top) until you feel the wires are solidly bound together and can't be pulled out of the wire nut.  Wrap a piece of electrical tape around the wires and the wire nut to secure the wires to the nut.  Repeat this process with the other two wires (one from the fan and one from the adapter), and you have made your electrical connections. 

 

Plug the power adapter into the AC power strip, switch the strip on, and verify that the fan spins.  If the wires are securely bound in the wire nuts, the fan should work.  While it is plugged in, hold the frame of the fan, keeping your fingers out of the way for the spinning blades.  (I know.....kind of obvious, but I had to add this warning just in case.)  Verify which side of the fan is blowing a stream of air, and mark this side of the fan housing with a piece of tape.  This is the side of the fan that faces up into the transparent wind tube.  Once you have verified all of this, unplug the DC power adapter from the wall outlet.

 

The supports for the fan and tube housing are 4 craft sticks.  For the prototype I used a rubber band to attach the sticks to the fan housing.  This allowed me to adjust the height of the fan above the table while allowing me to level the fan and tube assembly.  Later you can use a hot glue gun to permanently attach the craft sticks to the fan housing once you have determined the optimal height for the fan above the desktop.

 

The transparent tube itself is shaped by wrapping one of the photocopier transparency sheets around the craft sticks and taping it together to stay in a tube shape.  You will probably need an extra set of hands to hold the transparency tube in place while the tape is applied.  Remove this tube from around the sticks and use it to help shape another one or two tubes of the same diameter.  Simply tape these tubes together, overlapping about an inch where the tubes join.  Slide the tube assembly over the craft sticks above the fan housing. 

 

Now you are ready to test your Mini Wind Tube!  Plug the DC power adapter into the power strip and switch the strip on.  Experiment with very small pieces of lightweight material, such as packing peanuts or popcorn.  Drop one or two of these into the top of the wind tube and observe their behavior.  Do they float and spin for a while in the tube, fall straight to the bottom, or float right back out at the top?  Experiment with different shapes and weights of materials in your tube.  Try to find the best height of the fan above the table for optimal airflow.  Once you have determined this, use a Sharpie to mark the craft sticks for the fan housing position on the sticks.  Turn the fan off, unplug the power adapter, and slide the transparent tube off the sticks.  Use a glue gun to glue the craft sticks in place.  Set the fan assembly upright, slide the transparent tube in place, and plug the adapter back in. 

 

Challenge students to try to shape a small piece of paper in such a way as to maximize the time it floats in the tube without crashing to the bottom or flying out the top.  This is more difficult than it sounds.  That's it!   Have fun experimenting with your Mini Wind Tube!