## 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.
Awesome
Awesome
<p>How did you manage to calibrate wind power?</p>
Driving with a car on a calm day.<br>
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).&nbsp;
&nbsp;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.
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.
Hi ! There is some form to apply in this anemometer some circuit to know the wind speed? ppsailor
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
You were featured on supergluecorp.com.<br /> <a href="http://www.supergluecorp.com/blog/2010/03/30/happy-easter-happy-spring/" rel="nofollow">http://www.</a><a href="http://www.supergluecorp.com/blog/2010/03/30/happy-easter-happy-spring/" rel="nofollow">supergluecorp.com</a><a href="http://www.supergluecorp.com/blog/2010/03/30/happy-easter-happy-spring/" rel="nofollow">/blog/2010/03/30/happy-easter-happy-spring/</a><br /> (I am not affiliated with&nbsp; <a href="http://www.supergluecorp.com/blog/2010/03/30/happy-easter-happy-spring/" rel="nofollow">supergluecorp.com</a>, just thought I wold let you know.)<br />
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
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.
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.
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!
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?
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.
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.
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
Nevermind about my wind generator instructable, I'm basically doing the same thing as <a href="https://www.instructables.com/id/E0T6AVT19OEP286NG5/">https://www.instructables.com/id/E0T6AVT19OEP286NG5/</a> Chispito Wind Generator. I could just put up my own version.<br/>
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.
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 <a rel="nofollow" href="http://www.otherpower.com/anemometer.html">http://www.otherpower.com/anemometer.html</a> 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.<br/>
Sweet.<br/><br/>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.<br/>
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
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.
nice