I believe lvdt stands for "Linear Variable Differential
 Transformer".

                                        Regards,

                                           Jim




On Fri, 14 January 2000, "Smith, Clay" wrote:

>
> 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...

jim@jpes.com