I've been using an anemometer made by a company called InSpeed
(www.inspeed.com). They offer several different systems, but the basic
cup-type sensor (which they sell separately for about $50) puts out a
digital pulse once per revolution that is created by a magnet passing a
reed relay. InSpeed provides the calibration factor between
pulse-per-second and windspeed and the anemometer is rated to be
essentially linear up to 110 mph, so you could build your own simple
electronics to feed the pulses through a low pass filter and generate an
analog speed indication. It's a wired system ... not wireless.
For an additional $50 or so InSpeed sells a computer program that
accepts the pulsed output from the anemometer via a serial port and
displays min, max and average over a user definable interval. The
program will also datalog (datapoints every interval down to as often as
once per minute) to a .csv file for storage, or input and graphing by
The feature that might be most useful to you, however, is that you can
set an alarm in that program for whatever max speed you want. If the
actual wind speed exceeds the preset limit, an output on one of the pins
of the RS-232 connector is triggered. I believe that output stays
triggered until reset, but I don't remember for sure.
InSpeed also sells a version that packages the cup sensor with a
standard bicycle computer for a simple visual display, since bicycle
computers work much the same way except with a magnet on the wheel and a
reed relay on the frame ... InSpeed just uses a different calibration
factor to make the bicycle computer display windspeed.
I bought the anemometer with the computer program and both have worked
extremely well for me.
Rick Karlquist wrote:
> I would like to monitor wind speed using a simple
> cup anemometer to determine when it is time to
> crank down the tower. In looking for anemometers,
> I have only found extremely expensive solutions that
> indicate wind direction as well as speed, and require
> a complete "weather station" in the shack, and even then, no
> analog wind speed output voltage. All I want is a cup
> assembly connected to a velocity to voltage transducer
> (tachometer sensor).
> I found a source of anemometer cup assemblies at a
> place called Forcefield. I am about ready to build
> my own anemometer out of an old hard drive motor,
> but I thought I would ask what other people with tower
> anemometers are using (I know you are out there...)
> before embarking on this science project.
> Rick N6RK
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