Instructables
So my last project was a Arduino wind chill machine.
http://www.instructables.com/id/Arduino-Wind-Chill-Machine/

Naturally, this Lazy Old Geek wanted to add a weather vane (wind direction) to my weather station. Who cares, you may ask? Well, I am a Geek. Actually, wind direction has some importance. Here in the high desert, the winds are usually from the west. But sometimes we get some wrap around and the wind comes from the North or East which usually means it’s coming off the mountains and is probably colder. Also sometimes we actually get smoke blowing in from wildfires in Utah, Nevada and even California.

Example: Outdoor burning by permit is allowed in my county. Just the other day, there was some burning nearby and I could tell by my weather station that it was not going to be blowing in my direction so I could keep my window open.

 
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Step 1: Parts List

USB Freeduino (Arduino-clone) $ 22.50
Adafruit Data logging shield        $19.50
http://www.adafruit.com/index.php?main_page=product_info&cPath=17_21&products_id=243

SD Card                                           $ 6

Aluminum NoTrespassing Sign      $ 2
Potentiometer 6639S-1-103-ND   $12 (Digikey)
2 2”x 1/2” Mending plates              $ 1
100ft Ethernet Cat5 cable              $ 8 (Amazon)
2 Ethernet Couplers                       $1.40 (ebay.com)

Prices US dollars March 2011

Any USB Arduino should work but it is easier to wire it up to an Arduino shield so the clone would have to be shield compatible. There are some good deals on ebay for Arduino Duemilanove 2009 for about $18.

So why did I add the Adafruit Data Logging Shield, you may ask? Well, if I want to collect long term weather data say overnight, then I have to leave my computer on. With the data logger, I can record the data to an SD card and don’t have to keep the computer on all night.

The potentiometer is special in that it’s called continuous turn. Most potentiometers rotate about 350 degrees and stop. Those wouldn’t work for a weather vane. This one will keep rotating no matter what direction the wind comes from.
 

sir good project you have.. i will also do this one but i'm facing a bit of a problem in codings in arduino, i'm also a beginner in using arduino.. sir can i use/see your codes as a tutorial/backup so i can easily understand the project.. tnx sir..

msuzuki777 (author)  romillo.nokom5 days ago
Yes, feel free to use the Arduino code. It is in the zip file in step 6. I made another version with a rain gauge.
http://www.instructables.com/id/Arduino-Weather-Station-Part3-Rain/
with some more Arduino code.
Hope this helps.

LOG
kentek10 months ago

Question:

How much turning resistance is there with the 360degree POT you used?

I notice that your wind vane is very large. I would like to build one much smaller. Will your choice of POT allow a smaller vane in light wind?

Thanks

ken

msuzuki777 (author)  kentek10 months ago

I had no way of calculating the size of the weather vane size. Turning resistance is definitely a factor plus wind speed. But hardest to calculate would be the aerodynamics of the vane. I just kind of guessed on the size I needed.

TIP: One way to eliminate turning resistance of a pot is to use some kind of no-contact sensing. In one of my early designs I used a magnet and eight reed switches. Similarly, you could also use a set of hall effects switches.

But I don't think the turning resistance is a significant factor. My guess is that a better wind vane design(balance and shape) would yield a much smaller physical package.

Unless you are or know a good physicist, it's probably a lot of trial and error.

LOG

bpike12 years ago
Great project, have you considered interfacing it with wview opensource weather station software?
msuzuki777 (author)  bpike12 years ago

I hadn't heard of wview so looked it up. It looks like some nice software but seems to be Linux-based only. I don't have a Linux machine and haven't programmed in Linux/Unix for years so probably not.

LOG

By the way, I'm still using my weather machine almost daily and did add the rain gauge.

http://www.instructables.com/id/Arduino-Weather-Station-Part3-Rain/
kmalivuk3 years ago
Suzuki-san, Yesterday someone gave me an anemometer, but without a weather vane, that's only 1/2 the goal. Now you gave me the other 1/2 with your "ible" so thanks, truly! I will adapt it to a XBee radio, but your mechanical design is just what I'm looking for. I eagerly await your rain gauge!!
msuzuki777 (author)  kmalivuk3 years ago
I just published my rain gauge.

http://www.instructables.com/id/Arduino-Weather-Station-Part3-Rain/

How's your project going?

LOG
Right now it's sitting on the self because I'm painting my house, certainly not an instructable! However I was talking with a physicist friend who is urging me to consider an angular magnetic sensor, similar to:

http://www.gmw.com/magnetic_sensors/magnetic_sensors_ang_index.html

But I'm also getting ready to celebrate my mother-in-law's 88th birthday, so sadly, the weather station has just been relegated to a lower status for now. I look forward to reading your latest installment: the rain gauge. Thanks for thinking of me.
Karl
msuzuki777 (author)  kmalivuk3 years ago
Understandable.

My weather station is pretty low priority but fortunately, I don't have a lot else going on. Except I'm trying to help one cousin with a computer problem, another with a car problem and some plumbing problems of my own.

I am also trying to make a cheap USB-BUB.

That magnetic sensor site looks pretty interesting. I've been trying to find information that explains these sensors on a level I can understand. This does a pretty good job for those specific sensors. You're pretty lucky to have a physicist friend.

I was a little disappointed that my GPS couldn't give compass direction unless it was in motion. But now that I understand basically how GPS works, it makes sense. I would like to build a cheap digital compass.

Mike
msuzuki777 (author)  kmalivuk3 years ago
Thanks,

This is actually the second one I made. Many years ago I built one with a magnet and I think eight reed switches. The problems I remember were building some custom PCBs to mount the reed switches plus having to run nine wires back to the electronics. I like this design better.

I assume you're going to use the XBee to make it wireless? I'm curious as to how you do that as I've never used XBee.

I've started the rain gauge. It's based on the tipping bucket method but I have a way to go.

Well, I've never used the XBee either, and that's exactly why I'm going to jump in!

I looked at the datasheet for the continuous turn potentiometer and it said that the pot has an electrical angle of 340 degrees. Does this mean that there's a 20 degree dead spot in reading wind direction? Right now I'm tossed between a pot and a rotary encoder and all of the continuous turn pots I see seem to have that 340 degree electrical angle. I looked at pots on wikipedia, but haven't found an answer yet.
msuzuki777 (author)  kmalivuk3 years ago
You are correct, there is a dead spot. It didn't seem like it was 20 degrees to me but it could be.

For my purposes, I won't even notice a 6% error which 20degrees would be and I already limited my output to 16 distinct values which is 22.5 degrees each. I don't believe the Arduino will have trouble with the dead spot either as I think the Analog inputs have a built in pullup which would just dump the dead spot into the >2812 reading which in my case is South. I'm not going to know the difference between wind from the South or SSW anyway.

But you are correct, a rotary encoder would be better. I would be concerned about price, resolution, wiring requirements and decoding . Some of the cheaper ones seem to have 12 divisions per revolution which is 30 degrees.

If you find something you like, let me know.

Good luck with the XBee. I recently read an article where someone built a wireless rain gauge with a cheap wireless doorbell. I thought that was pretty innovative.

LOG
Well, good news, some bad news, and then more good news: I found Vishay pots with electrical angles of 352 degrees, but sadly they start at about 40 bucks! However I discovered that where I live, Albuquerque, essentially no wind arrives from approximately NNE to ENE with a "null" at about NE. So, if I center the 20 degree dead spot at NE and massage the code slightly, I can pretty much cover all our local winds with the reasonably priced pot that you used. Time to start building...
pilotniq3 years ago
One option is to attach a magnet to the vane, and use a 2D magnetometer to read the angle, High precision, won't wear out, and you can weather seal the electronics without an axle going through the case.

If you do this. make sure you get a magnetometer that's not limited to the earth's magnetic field strength (I made that mistake first)
msuzuki777 (author)  pilotniq3 years ago
Sounds like a good idea. I've never worked with magnetometers and don't know much about them. Where do you get them and about how much are they?

Thanks,
kmalivuk3 years ago
I just found this:

http://www.bourns.com/data/global/pdfs/OnlinePotentiometerHandbook.pdf

and on the bottom of page 133 and the top of 134 it does say there is a dead spot, though the concern in the article has more to do with torque. Now I'm even more tending toward a rotary encoder.