At 06:36 PM 5/9/2007, 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).
Do you actually need a voltage, or just something that tells you when
the speed is over a certain value. For the latter, how about a
pendulum hanging in the wind with a conductive ring around it (like a
pinball machine tilt sensor). If the wind blows hard enough, the
pendulum is pushed to the side, makes contact,
etc. Calibration/adjustment by the "hold out the window of the car
on the freeway" approach.
It will also sense earthquakes, but in that case, you probably also
want to crank the thing down.
Another, more direct approach to your problem: What about a
straingage sensor on the tower itself, using IT as the sensor. Put
the strain gage at the base and when the strain exceeds some TBD
value, it's time to crank down. Omega engineering has cheap
straingages that you can just glue on. You might also be able to
just measure the deflection of the tower by a variety of means. Say
you had a Laser pointer shining up along side the tower, and a
reflector at the top that would move into the beam when it deflected
too much. When you see the beam coming back down, it's time to crank
it down. Or, put the laser at the top pointing straight down, and
have a ring/annular shaped photo sensor. If the light hits the
sensor, you trip. Probably want to pulse the laser so that you can
AC couple the photo sensor to eliminate the effects of daylight.
Jim
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