ask how arduino detect wind speed

Hi, :) i have arduino uno r3 and i want my arduino to detect the wind speed so i buy an encoder with optocoupler. The encoder will be fitted with propeller, so wind will drive the propeller and encoder will rotate. optocoupler used to read the signal from encoder. it will be look like this : |500x350

so, my question, is it possible to detect wind speed with that way and do i need other thing like schmitt trigger?

What you have drawn should work. The sensor needs to be connected such that there is a R (10K or so) from 5v to the input and phototransistor from input to ground.

You can then count the revolutions in a known time and hence determine a relative wind speed. If you need a true accurate speed, you need to calibrate it against a known wind speed.

Weedpharma

weedpharma: If you need a true accurate speed, you need to calibrate it against a known wind speed.

One way to do this would be to drive a car with a sun roof along a straight road on a calm day. Use a GPS/Sat Nav (not the car's speedometer) to measure the vehicle speed at, say 50Kph. Fit your sensor on a pole so that it projects perhaps 1M above the roof of the car. Write a sketch to measure the pulse width of the signal from the optocoupler. Repeat the test at other road speeds.

An inexpensive ready-made wind sensor that I use is this one. The reed switch inside opens and closes twice in each revolution. One revolution per second is equivalent to 2.4Km/hr windspeed.

There is also this type of sensor.

Paul

ok, thanks for reply, i'll be test it soon :)

There is a way to do this without rotating parts. It can be done the same way your new cars measure air mass. It has thermistors, some in the air flow and some reference. As long as you are not intending to go too much change in altitude, it can be more accurate than the spinning anemometer. Add one of those air pressure sensors and be even more accurate. Add a moisture measurement and be really accurate. You might experiment with the same car method and a thermistor. You need to feed current through is to make it warm. Dwight

dwightthinker: There is a way to do this without rotating parts.

Yes Dwight, I already gave a link to one like that in post #2.

PaulRB: Yes Dwight, I already gave a link to one like that in post #2.

Oops, didn't follow the second pointer. That is cool that it is only $17. I have a friend that lives on top of a ridge, in the mountains near hear. He periodically has to get a new spinning anemometer. They are said to be rated at 175 mph but the cups keep flying off. And, not it is just storms and not hurricanes. Putting the anemometer out the window to the side has less disturbed air than over the top. The air close to the car is moving faster because it is squeezed as it goes over the top. Dwight

Propellers make poor wind speed indicators as they will only correctly measure the wind speed if its directly on axis , ie blowing directly thru the blades. Off axis wind which you get with any turbulance will read incorrectly. This is why anemometers are always used by Met agencies to measure wind speed.