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.
Ingredients:
- 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.
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.
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.
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.
Extras:
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.
