Easter Egg Anemometer (Wind Speed Meter)





Introduction: Easter Egg Anemometer (Wind Speed Meter)

Easy homemade anemometer, this goes together quickly if you have the parts laying around. This is basically a mini wind generator; the spinning motor produces a current that a multimeter reads.
Inspiration for this project comes from http://www.otherpower.com/
1 cheap $3 analog multimeter
3 or 4 easter eggs*
1 telephone wire with ends clipped off
3 or 4 - 3" screws*
1 DC motor out of CD ROM drive
1 circular wood cutout from hole saw
1 hose clamp or bracket for motor mounting
1 broomstick or pole
Extras: whiteout, solder, super glue, and electrical tape

*"3 or 4" refers to how many cups you prefer on the rotor.

Step 1: DC Motor

Take the DC motor out of an old CD ROM drive, there were three inside the one I had. Keep the little gear wheel part of the motor to glue the wood rotor onto. Clip and strip the ends of the telephone wire, multimeter leads, and motor wires and solder + tape it together. I used an old CB antenna mount for this but a hose clamp would work well too.

Step 2: Rotor Assembly

Use a hole saw to cut a little wood disc for the rotor assembly; predrill the screw locations. Find a good location on the eggs halves and drill the 3" screw through it from the inside of the egg. Hand screw the screws into the wood disc. Balance can be adjusted by adjusting the screws. Mount the rotor assembly onto the motor; you may have to drill the center hold in the wood a little bigger to fit onto the plastic gear. Super glue wood to plastic.

Step 3: Calibration

Take the bargain bin multimeter and pop off the clear plastic, paint whiteout on the numbers but keep the dashes. Set the multimeter to DC mA and spin the rotor to see how it works. Now you can mount it to a broomstick and have someone drive you down a back road on a still night while you hold it out the window to calibrate it. Take a sharpie permanent marker and mark dashes on the multimeter. Snap the clear cover back into place and mount your new anemometer.

Step 4: Video


I glued an extra egg on the wood as a weather shield and put liquid electrical tape on all over the motor to seal it.

Below is a template for lining up a three-cup rotor.



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    How did you manage to calibrate wind power?

    Driving with a car on a calm day.

    how do you calculate a wind speed.

    How was the unit callibrated?

    Car window trick: stick the anemometer on a broomstick, stick it out the window while somebody drives various speeds down a back road; use a marker to make dashes at the 10 mph, 20 mph, etc.


    You could also calibrate by manually turning one of the cups and calculating the speed using the length of one of the screws (since the cup is traveling in a circular path of which the screws are radii). 


     Of course I should note that this only measures the speed of the cup, which might be slower than the actual windspeed.

    There is a way to measure the resistance as well - and can be done at home for cheap as well - if you have the supplies - what you need is a way to measure the amount of force needed to set the blades turning a full cycle. This would be your anemometer's wind resistance. This can be done numerous ways, a small electronic scale will work for example - but not as well as an air compressor that can be set to extremely low psi. Once you have this you can then calculate the wind mph with the above measurements as accurately as this method allows.