Anemometer

[RA]

After long searches in the WEB I decide ask experienced people about anemometers output signals. If anyone met with measuring the output signal from wane or cup anemometer - what type of signal is coming out. is it the pulses or voltage/current ?

my idea is to use ADC to send signal to PC and then make some manipulations with soft like LabView or other, to build the registration device for my turbines and next step will be feed back with DAC to operate with controller. If anyone have such experience and will share with me I'd appreciate.    

[Flux]

Virtually every anemometer is different. Most produce some form of signal related to speed( frequency) some have it chopped to a pulse level others have a signal that needs feeding to a comparator to get clean pulses.

In some cases with generator types the voltage is also more or less proportional to wind speed but the spec is usually defined from frequency.

Once you choose your anemometer you should be able to find its type of output and frequency/mph relationship from the web site.

With some such as the NRG you have a choice of the magnet generator output or a more expensive version where the generator output is squared and converted to pulses. The frequency is the same for both.

Flux

[madlabs]

As Flux said, there are many different types. Do you have access to a 'scope? If so, sorting it will be easy. If not, it can be a little harder. I have an old one that uses IR LED's and a wheel with opaque/transparent sections. At low speeds it needs a Schmitt trigger to give clean pulses. Bottom line, pick one and we can help ya get it going, but there are just too many to be able to be specific until you do.

[RA]

Thanks for information. I think I have find the pulse-volatge converter circuit or build it by myself ,then ADC.  

[rossw]

My "Young Instruments" helicoid propvane (which is a proper WMO spec instrument) produces a small AC output, the frequench of which is proportional to windspeed.

Rather than converting freq to voltage, then reading with an ADC (both of which intruduce errors), consider measuring frequency directly.

My old original weather station (circa 1985) was made without reference to any existing design. I took the AC from the head, through an op-amp set with basically open loop, and the two AC leads to + and - inputs. The resulting (nearly) squarewave output was fed to a 12-bit counter.

Under software control, I would read and reset the counter and store a times (in milliseconds). This gave me a count, and a time over which it happened, that directly converted to frequency with virtually no error (just timing error, which was minimal).

Using todays PIC and microcontroller chips it'd be even easier as they have all that built into them.

[willib]

I built my own out of a muffin fan.

http://www.otherpower.com/images/scimages/2965/anemometer_on_pipe.JPG

http://www.otherpower.com/images/scimages/2965/anemometer4.JPG

If you can find one with a third ( yellow ) wire coming out of it , this wire is a built in tachometer circuit,which outputs a squarewave (two pulses per revolution).

To Decog it you have to do a little surgery to remove the armature ,but not the circuit board.

When this is done it spins freely and applying 5V to it ,it outputs a signal proportional to its rate of rotation .

Bill

[RA]

I should look around. do that fans have permanent magnets inside? idea just to use it in opposite direction to genrate some AC , if there is no tacho inside

[ghurd]

DC muffin fans have magnets.  Seems to most commonly be a strip of fridge type magnet.

I made a few generators out of DC muffin fans.  Story shows the guts,

http://www.fieldlines.com/story/2008/1/15/19920/9192

G-

[willib]

I just checked three open PC's that i had laying around, two (fans) had three wires coming from them. Check the CPU fans of the Pentium II vintage , since they monitor the fan speed on the motherboard.

yeah you could try making a gen out of one , but the shape of the blades in the fan dont really lend themselves to power generation, and it will not even turn very well if you leave the armature in there, because of cogging.