Anemometer


16 posts
by squarepie » Sat Mar 16, 2013 9:23 pm
I'm building a raspberry pi weather station. Does anyone know how to make an anemometer? The only premade ones I can find online are handheld ones which are pretty useless for my project. Also I am interfacing it through i2c and Dallas 1 wire.
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by aTao » Sat Mar 16, 2013 10:12 pm
All you need is to count the revolutions on just about any windmill. 4 plastic cups on 2 dowels fixed in a cross would be an extremely basic example.
At first "Google" I2C frequency counters seem rare, so you could make one, use I2C gpio expander to read a counter that is clocked by an encoder on the windmill shaft and reset every second.
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by klricks » Sun Mar 17, 2013 12:14 am
Here are 2 ways:

1. Magnet and reed switch -. A magnet mounted to a shaft or cupset spins around the shaft. The reed switch is mounted so that the magnet passes over it and opens and closes the reed switch contacts as the cupset turns. Could be interfaced to the RPi with little or no additional electronics.

2. Chopper Wheel - Pulses are generated by shining a light source such as an LED through a slotted wheel mounted on the cupset shaft. A detector on the other side of the wheel detects the light / dark pulses as the wheel spins. Some additional circuits would be needed to run the detector and generate usable pulses.
Go here for my RPi writeup. Basic config, Serial Port add-on etc:
http://home.budget.net/~klricks/Comp/RPi/Rpi.html
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by vk4tec » Sun Mar 17, 2013 9:40 am
Computer mouse

LED wheel and RX - older ones
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by Burngate » Sun Mar 17, 2013 11:34 am
You could always try for a non-mechanical one - ultrasonic transmitter and three receivers, measure the delays to work out wind speed and direction
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by aTao » Sun Mar 17, 2013 11:36 am
Burngate wrote:You could always try for a non-mechanical one - ultrasonic transmitter and three receivers, measure the delays to work out wind speed and direction

Nice!
If you also want to measure wind direction the ultrasonics could be mounted on a weather vane.
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by VENTS » Sat May 11, 2013 12:14 pm
Hi,
You can see that ultrasonic anemometer :
http://www.lcjcapteurs.com/?lang=en
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by Burngate » Sat May 11, 2013 5:30 pm
VENTS wrote:Hi,
You can see that ultrasonic anemometer :
http://www.lcjcapteurs.com/?lang=en
That's the one!

Actually it was a long time ago that I saw an article about it, so LCJ Capteurs may have commercialised it in the mean time.

Solid state, no moving parts, brilliant.
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by klricks » Sat May 11, 2013 7:39 pm
Burngate wrote:
VENTS wrote:Hi,
You can see that ultrasonic anemometer :
http://www.lcjcapteurs.com/?lang=en
That's the one!

Actually it was a long time ago that I saw an article about it, so LCJ Capteurs may have commercialised it in the mean time.

Solid state, no moving parts, brilliant.


Sonic anemometers are not a new technology (several decades). Many companies make them including the company I work for. http://www.metone.com/
Most Sonic wind sensors can measure wind direction as well as wind speed. (By definition anemometer is wind speed only). Some even have temperature measurement. Sonic wind sensors are fairly complex and require digital processing electronics (CPU) embedded in the sensor.
Sonic wind sensors are expensive as well..... several hundred to well over 1K$ US.

http://en.wikipedia.org/wiki/Anemometer
Go here for my RPi writeup. Basic config, Serial Port add-on etc:
http://home.budget.net/~klricks/Comp/RPi/Rpi.html
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by trevj » Tue May 14, 2013 2:23 pm
I found what look to be some useful links. Apologies if they've already been noted elsewhere in this forum.

http://blog.makezine.com/2010/06/04/how ... ter-to-an/
http://www.thingiverse.com/thing:41367
http://www.yoctopuce.com/EN/article/how ... ind-part-1
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by richardp » Tue May 14, 2013 3:44 pm
http://www.maplin.co.uk/n25fr-wind-speed-sensor-676620

I can't build it for less than £2.50 - So I would buy one and hack it up.
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by wstein25 » Fri May 31, 2013 4:01 pm
I've been messing around getting an RPI set up as a web server showing real-time wind data. I'm using a (relatively) inexpensive 3 cup anemometer with a reed switch that generates pulses - the rate dependent upon the wind speed. Instead of trying to count the pulses with the RPI directly, I have TI's MSP430 Launchpad (US$ 4.30) set up to do the pulse counting, and make the data available at its serial port.

This then is fed to the RPI serially, and saved as a single line file on the RPI. Just a bit of PHP code can put this on the web page that the RPI serves. I will get around eventually to writing this all up if anyone is interested. (A bit of shameless promotion - you can see the data at our facility here: http://174.63.120.250/

I have limited the updating to once every 10 seconds, as I had concerns about the reliability of the SD card memory. It doesn't push the data, you have to refresh the page to see current data.
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by wstein25 » Sun Feb 02, 2014 5:03 am
I have changed the Raspberry pi web server address to the alternate port 8080 i.e.
http://174.63.120.250:8080
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by scruss » Wed Feb 12, 2014 5:55 pm
Care to do a short writeup, wstein25? That's a decent solution to a complex problem, and pulse counting are what little µc boards are made for.
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by wstein25 » Thu Feb 13, 2014 4:11 pm
I can't guarantee when I'll get around to writing this up. I'll do my best over the
next month. Perhaps I can post bits of it as I get it done. Do you have any particular
aspect of the project that you would like to see first? HW / SW , MSP430 code etc?

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by scruss » Thu Feb 13, 2014 9:15 pm
The MSP430 bit would be perfect, thanks. It's a nice cheap way to interface weather sensors, and might help to isolate the Raspberry Pi from the bad things that weather sensors have to deal with. No rush at all.
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