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Forum Index : Windmills : wind speed monitor
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makourain Senior Member  Joined: 19/04/2006 Location: Posts: 111 |
i want to make something to measure windspeed. so i was wondering if you could give some more details on how you made this; http://www.thebackshed.com/Windmill/images/Dscf0912.jpg since i dont have a bicycle computer could you suggest something else that i could use? i was thinking of getting some paper cups, sticking them on some dowel in a 3 blade type design and have the paper cups out to scoop the wind. get someone to drive the car at a certain speed and measure how many volts a little dc motor produces. |
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| RossW Guru  Joined: 25/02/2006 Location: AustraliaPosts: 495 |
Making linear-output anemometers is non-trivial. Probably, the most important question has to be "how LOW do you want it to measure from?" - because this will largely determine how you build it. I run several anemometers. Without a doubt, the best of them is the young instruments helicoid propvane. It has a low startup speed and almost perfectly linear response up to about 200 KMH. The one instrument measures wind speed and direction, but it's fiendishly expensive. Even more expensive but ever-so-neat, is the no-moving parts ultrasonic sensor. I won't go into detail on that one, as I doubt any of us can afford one any time soon! One of the most innovative ideas I've seen has been a 3-cup type anemometer with two standard cups, and one over-size cup. The thing is electronic and measures rotational speed with an optocoupler, so there is very little mass and no "cogging" at all. The neat trick with this guy is that it can measure speed *AND DIRECTION* without using a wind-vane. I believe it's an Aussie design and available in kit-form over the internet. From memory, it was reasonably inexpensive too. There are also plenty of commercial "weather stations" at various levels, some for a hundred bucks or so, which have quite respectable (albeit "cheap") anemometers. The really cheap ones usually don't have a computer interface, just a remote display head. Finally, many years ago I saw someone who had used an old (mechanical drive) speedo from a car, with a turbine of some description, as a home-made wind-speed indicator. I have no idea how the heck he ever calibrated it, nor how low its start speed was, but it seemed to work well enough for his purposes. [Edited] Well, I went to find the article for you, but alas, the "DIY Rotorvane Anemometer" site as been removed. It is no longer being sold either as a kit, or parts. Some of the material is still available in googles archives though if you're interested. A quick search failed to find anyone else selling the same thing, which is a pity. Reasonably well made versions were reported to have 5 degree accuracy, and precision versions about 1.5 degrees. |
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Megawatt Man Senior Member Joined: 03/05/2006 Location: AustraliaPosts: 119 |
Silicon Chip magazine has just published an article on a DIY anemometer, using a shaft and motor from a discarded VCR, cups from a kitchenware shop, I think, and maybe a speedo calibrated in wind speed. It would have been one or two issues ago. Megawatt Man |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5019 |
Be carefull of anything you stick out a car window. My first attempt at a anemometer consisted of a PC fan with the electronics removed. I had a AC meter across the coils to measure voltage. The faster the little fan, the higher the voltage. Well I took it for a drive and at 100kmh I stuck it out the window. Bad idea. The fan spun up so fast it screamed and I was reading over 300 volts! Dangerous! And when I slowed down the little bearings had failed. It crunched as it rotated, so threw it away. When I build the one shown on the web site, I only tested to 60kmh, thats more than fast enough. The bike computer was only $35 from Dick Smith I think, pretty cheap for all its built in functions. The rest of it was from bits in the scrap box, except the ping pong balls. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| makourain Senior Member Joined: 19/04/2006 Location: Posts: 111 |
http://www3.telus.net/chemelec/Projects/Anemometer/Anemomete r.htm this can only measure windspeed up to 4.5kmh and the guy who put it on his site doesnt know how to make it detect faster windspeed. i need something that can detect windspeed from the slowest speed that a smart drive windmill will run to the maximum that it should run. my idea is to go around to different suburbs and record wind speeds and directions and see where good wind turbine places are around the place, and to detirmine if a vawt or hawt would be better in those places. |
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| KiwiJohn Guru Joined: 01/12/2005 Location: New ZealandPosts: 691 |
Hmmmm, I have seen the ultrasonic anemometer and yes they are expensive. However. there are not plenty of ultrasonic transmitters and sensors in car parking warning systems and anyway I think they are quite cheap from Dick Smiths. Also, practically every PC has a stereo sound card, any chance someone doing the software to put them together? |
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| Megawatt Man Senior Member Joined: 03/05/2006 Location: AustraliaPosts: 119 |
OK, I have the reference to the Silicon Chip magazine article. It was March 2006. The anemometer was made from the shaft/bearings of a VCR video head to which were attached 3 stainless steel measuring spoons at 120 degrees, to make a 3 element savonius rotor. On the end of the shaft a plastic slotted wheel was fastened and this interrupted the light between a LED and the sensor on a computer mouse. The output voltage from the mouse, linearly dependent on rotational velocity supplied an amplifier from a disused cassette player and the player's output supplied an electronic speedo in series with a potentiometer. The unit was calibrated with the pot and registers wind velocity from zero to 120kph. Cost was $1.00, using bits collected from tips and relatives. Megawatt Man |
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Chris Senior Member Joined: 12/09/2005 Location: AustraliaPosts: 146 |
http://www.sci-spot.com/Mechanical/dyno.htm Thats a interesting site. You can use any mouse to make a dynometer and it includes software. Wouldnt be hard to customise for a anemometer i think. |
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