Instructables

Easter Egg Anemometer (Wind Speed Meter)

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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/
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.
 
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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.
giize1 year ago
how do you calculate a wind speed.
oldcolonial5 years ago
How was the unit callibrated?
robbtoberfest (author)  oldcolonial5 years ago
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). 
hac hac4 years ago
 Of course I should note that this only measures the speed of the cup, which might be slower than the actual windspeed.
Tetsuoh hac1 year ago
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.
how do you connect the meter to the DC motor again? can you tell me, like step by step? cos I didn't really get it.
ppsailor4 years ago
Hi ! There is some form to apply in this anemometer some circuit to know the wind speed? ppsailor
pprobots 010.jpganemometros 051.jpg
robbtoberfest (author)  ppsailor4 years ago
I'm not understanding what your comment is asking.
he's asking if there is a circuit to measure the wind speed being detected by that anemometer
scratchr4 years ago
You were featured on supergluecorp.com.
http://www.supergluecorp.com/blog/2010/03/30/happy-easter-happy-spring/
(I am not affiliated with  supergluecorp.com, just thought I wold let you know.)
outlawmws5 years ago
Nice write-up; I have just completed calibrating the one I built using your write-up as the inspiration. Main differences: I used the motor for the tray (in/out) from the CDrom. It mounted inside a piece of 1/2" PVC after I drilled it a shade larger (5/8”) and used a nylon bolt as a set screw to hold the motor. I oriented it open end down to keep rain out, and cut a PVC coupler in half to make a drip edge to keep rain out. The wires went inside the PCV pipe through a 90 deg elbow, and to about 18” of ¾ PVC. This larger pipe was capped and two machine screws act as studs for connecting the wires. All the PVC was epoxied, (which leaves a nice bead that paints well) The arms were popsicle sticks, and the Easter eggs were notched on one side, and a small hole drilled on the opposing side to “Key” in a nub I left on the popsicle stick. Again Epoxy was used to attach everything, and again this left a nice radiused bead. Te motor had a small plastic beveled gear, and a flange with slots in it (probably for a motor control bit…) and that is what the Popsicle sticks were epoxied to. I painted it all, and used a tiny fishing bobber with one end sanded off to cap the gear and add epoxy to the hub. The horizontal PVC pipe will be U bolted to a piece of wood, and that will be clamped to some ¾” conduit for a mast. This gets mounted on the roof of the house. Phone wire will run down to the cheaper voltage meter, and yes, the 50ma scale works well. Voltage readings are useless as the voltage tops out at about 1.5 volts and you get no voltage under about 30 mph. The scale is constant from 20 to 50 MPH, at 5 and 10 MPH the marks read differently probably due to low rotation efficiency fall off. What I found was that for 20, 30, 40, and 50 MPH the meters 0-50 scale matched, (YMMV). 5 and 10 MPH do not match any standard step. Thank for the inspiration! -Outlaw
ncblu5 years ago
you can also use an old hard drive motor, keep the hub on the shaft and any screws that were with it. take an old cd and fasten it to the hub - you might have to tailor it to fit flat on the hub, screw the cd to the hub and mount the eggs to the cd. as for the meter circuit thats entirely your choice. i built one and its working rather nicely
amk5035 years ago
Very clever method. I took an alternate approach, using a small DC motor as the base (and for no other purpose), and essentially turning the shaft into a rotating switch which completes a circuit once per revolution. With the help of a microcontroller (which times each revolution among other things) and some basic math it was not necessary to calibrate the device. The wind speed is displayed with an LCD display stolen out of an old microwave.
robbtoberfest (author)  amk5035 years ago
Thanks, that sounds spiff. Can you post a picture? This project I tried to avoid circuit stuff since I have no clue when it comes to electronics.
codesuidae7 years ago
You could probably use some resistors (and maybe a potentiometer for fine tuning) to adjust the output of the motor to match the existing scale on the meter. Then you could use a digital meter instead of analog.
how bout a window comp circuit!
static6 years ago
Here's how the oldtimers tell me how they did this when they where kiddies. Some became friendly with those at a local airport or radio station mounted the homebrew anemometer there and calibrated it to the professional anemometer read out. Others used a vehicle using a jig like otherpower did. They took measurements as they drone in on direction, as well as taking measurements on the return trip to get an average. The more particular also drove a route 90 degrees to the first to have more data to average. As shown at otherpower they made new faces for the meters to measure in MPH. They done this long before PM motors where not as prevalent as they are today. Most used car heater motors that required a power source to the field windings. robbtorfest; did you have the sending unit that low to the ground for testing and photo purposes and, now have it mounted higher to collect the data. for blade design?
robbtoberfest (author)  static6 years ago
It is about 10 feet off the ground, about the height of the playhouse wind generator I plan to finish sometime this winter. I was just trying to figure average wind speed in my back yard just over fence height. Wind speed is a factor for blade design. Otherpower.com is a great site for this kind of info; that's where this idea came from.
ewilhelm7 years ago
Why are you measuring the wind speed? Hopefully something fun. Around here, we'd rig it up to a big siren that told everyone to drop everything and go to the beach.
robbtoberfest (author)  ewilhelm7 years ago
Wind generator coming soon using a treadmill motor, just need some speed numbers to help design the blades.
can not wait to see the wind generator
robbtoberfest (author)  wombat77 years ago
Nevermind about my wind generator instructable, I'm basically doing the same thing as http://www.instructables.com/id/E0T6AVT19OEP286NG5/ Chispito Wind Generator. I could just put up my own version.
Shubaltz7 years ago
I made one of thee for a 6th grade weather project (Needless to say, it got an A). I used a brushless DC motor, same as someone mentioned, from an old harddrive. I would reccomend one of thoes instead, as they are alot slimmer, and the main thing, they have less moving resistance. But hey, if it works for you, al the more power to ya.
i saw another Anemometer that used easter eggs, but they used an old hard drive motor and used frequency instead of voltage for measurements. They say the problem with using voltage and old DC motors is that at higher speeds, the motor will produce less electricity per MPH. If this miltimeter could measure frequency as well, you could get a more accurate reading buy just swapping motors.
robbtoberfest (author)  shadymilkman7 years ago
The mA output should be consistent even though less electricity is produced at higher speeds and with the calibration this shouldn't be a problem. I could be wrong, but those are my thoughts on it.
i found the site http://www.otherpower.com/anemometer.html its really interesting, and it has several reasons to use an HD motor over regular DC motor. I do admit that at the time i read it i wondered how to make one out of a normal DC motor. There is more than one way to skin a cat i guess.
Kiteman7 years ago
Sweet.

Regarding calibration, though, you'd have to make sure that the anemometer is well away from the car as you drive, since the displaced air rushing past the car is moving faster than the car itself, plus do it on a *very* calm day, as any wind that is already blowing will affect your results.
acaz937 years ago
hay , can you add a bit more of information about the measurement of speed ( i mean Explainig How Much mA equals How Many Speed ) And This is one of the better homemade projects i ever seen
robbtoberfest (author)  acaz937 years ago
I set the dial to the lowest setting 0.5 DC mA and that is the setting that responded best to the motor I used. Different motors with different voltage ratings affect the needle on the gauge; also the length of wire from the multimeter to the rotor/motor. That is what the calibration in the car should correct; just have the driver yell out speeds and have your marker ready. I hope that helps, thanks for the comment.
theRIAA7 years ago
nice