Anemometer stage 1

[BadNIMBY]

Have been working on an anemometer I can use to start recoeding the variations in the wind over the course of the year.

The hub assembly is an old VCR head scrounged from a broken VCR, The housing is a piece of PVC guttering pipe, there is a small rotor from another motor I found in the VCR unwound and now cradling a fragment of NDFEB. The cups are made from the tops of a roll on deodorant and is good and thick, very sturdy and responsive..

I will use a reed relay glued to the inside of the housing in line with the magnet. A 1-wire dual counter (http://www.hobby-boards.com/catalog/product_info.php?cPath=22&products_id=42)

will count the number of switch closures. This info will be sent back to the PC (later an standalone network Hard Drive)and logged.

Using Java the inputs from this will be converted into windspeed in mph.

Well thats the Idea...

I was wondering if others have gone down this route before and how they went about calibrating, ive read plenty on the calm day driving with the anemometer on a stick, this would work fine.

I will need a rough graph of speed to rpm

However in the Java program there is a formula to convert switch closures into mph:

Windspeed = counts / time * (N)

where N is a number to convert the rotation into windspeed, Counts is the number of switch closures

My magnet rotates 2cm from the axis

I can get the "N" by trial and error but wanted to see if anyone had better ideas than me (shouldnt be too difficult)

Thanks

Will

Pics arent over 50k each, size a little large tho, hope it isnt a problem.

[scottsAI]

Hello BadNIMBY,

The cups move at near wind speed.

Cup speed = k * wind speed

If your design is good; k will be near 1 (one)

If your design is good; k will be linear with wind speed.

Most anemometers assume k is 1.

Very hard to calibrate better than the assumed 1.

Where can you get a speed that is better than 10% error?

Calculation

Measure from the center of the cup to center of the rotation shaft.

Wind speed accuracy will be based on the accurately of this measurement.

(do not care about the distance of the magnets)

Calculate the circumference of one cup rotation, this is the path the cup takes at wind speed.

Rotation count will depend on number of magnets.

The rest of the math is straight forward. The counts vs speed will depend on how long you want to count for the time measure.

This what you wanted?

Have fun,

Scott.

[BadNIMBY]

Got me convinced, shall give it a twirl

Will let you know how it goes, at the moment I have 1 magnet but may have 2 as it will allow better resolution at v low wind speeds, not really useful for wind turbines but great for general weather info and if your gonna stick something on a pole, you might as well stick other things up their as well..

Thanks for your help

Will

[Speo]

I did it just a little bit different, check it at www.windpulse.com in the logging anemometer section.

Speo

[Speo]

I did it just a little bit different, check it at www.windpulse.com in the logging anemometer section.

Speo

[mukunthko]

and to think i spent a $100 in an anemometer with data logging from inspeed.com

what was i thinking?

[luckeydog]

mukunthko

 How do you like your inspeed Anemometer?

dose it work well?

is it built well?

was it worth the $100 ?

I was considering buying one and I am not sure

if I am sold on it yet.

Thanks

.

[mukunthko]

yeah inspeed is quite good. works well. They charge you extra for a parallel port and the software. If you just get the anemometer, its a lot cheaper. You can buy a parallel port for a lot cheaper and the software is a free download on their website anyway.

[coldspot]

 
I like the "www"
But I still hate getting
"web site you were trying to reach is no longer available."
Then you go back and look at the post date,.,.,.
 

Life-
Not trying to get out alive,
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$0.02