I have a collection of anemometers,
3 x Didcot
3 X Davis
3 x NRG #40C
and 5 X FO/Maplin. for UK residents these are very cheap
http://www.ebay.co.uk/itm/Pack-of-5-Mapl...1ea1e4c2f7
£7.99 for a pack of five! Type "wind sensors" into ebay.co.uk
Unfortunately I do not have the time nor the money to set these up to conduct a proper scientific experiment. Measuring wind speed is notoriously difficult and one would have to find a calibrated gauge to run as a base value to compare the others against. My NRG's were calibrated but some time ago and the calibration certificate expired about 5 years ago and it outputs a sine wave making it difficult to use on Weatherduino. See attached.
Werk suggested a Schmitt Trigger and I am looking into this but it is a bit beyond my current electronics expertise.
I accept that the FO instruments are Simple but there are many other variables to consider, bearing drag, cup accuracy, and many others, the trouble with measuring tiny parts of huge things is that tiny errors quickly multiply. See the bearing arrangement for the NRG sensor.
http://www.windandsun.co.uk/media/277060...-sheet.pdf
3 x Didcot
3 X Davis
3 x NRG #40C
and 5 X FO/Maplin. for UK residents these are very cheap
http://www.ebay.co.uk/itm/Pack-of-5-Mapl...1ea1e4c2f7
£7.99 for a pack of five! Type "wind sensors" into ebay.co.uk
Unfortunately I do not have the time nor the money to set these up to conduct a proper scientific experiment. Measuring wind speed is notoriously difficult and one would have to find a calibrated gauge to run as a base value to compare the others against. My NRG's were calibrated but some time ago and the calibration certificate expired about 5 years ago and it outputs a sine wave making it difficult to use on Weatherduino. See attached.
Werk suggested a Schmitt Trigger and I am looking into this but it is a bit beyond my current electronics expertise.
I accept that the FO instruments are Simple but there are many other variables to consider, bearing drag, cup accuracy, and many others, the trouble with measuring tiny parts of huge things is that tiny errors quickly multiply. See the bearing arrangement for the NRG sensor.
http://www.windandsun.co.uk/media/277060...-sheet.pdf