What you describe is called an lvdt.  Run an AC current thru a transformer
or inductor and move a spring loaded ferrite core in against a calibrated
spring and rectify the output.  You will have a voltage proportional to the
force on the lever
CSS

                -----Original Message-----
                From:   Wagner Lipnharski [mailto:wagner@USTR.NET]
                Sent:   Friday, January 14, 2000 12:20 PM
                To:     PICLIST@MITVMA.MIT.EDU
                Subject:        Re: Windspeed circuit?

                You can develop any kind of sensor, by wind pressure,
differential
                pressure, weight lifting (wing), rotational blades (most
common), or any
                other. Some will generate a linear voltage (requires an ADC
conversion),
                some will generate pulses (that should be accounted by
time).

                In any case, the most difficult task is to calibrate the
unit. Even if
                you install the unit outside your car and drive in a not
windy day, who
                ensures that your car's speedometer is calibrated?  If you
want to go
                for some accuracy you will need to use a professional
laboratory or wind
                calibrator.

                Is there any practical method to measure air speed (low
accuracy)? as
                for example, imagine a 12x12 inches 1/8" aluminum plate hang
by two
                nylon wires 3 ft high, wind directly over the plate, how
much will be
                the deflection of the plate at 10mph? 20mph? is there
anything like that
                for practical purposes? as is the original knots measurement
in
                boats...  (I am curious about that).

                Wagner.

                "Peter L. Berghold" wrote:
                >
                > Hi there folks,
                >
                > Anybody out there know of plans on the web for a wind
speed indicator?  I
                > would assume that it would involve some sort of pulse
counting scheme...