Mike, you could extract the frequency but it would defeat the
purpose of using a sensor with a linear DC output. This would
require extracting a ~100-200mv signal riding the DC. For low-cost
applications, you could use a basic sensor element such as Philip's
but you would need much more support circuitry for the oscillator.
I'm sure there are conditioned, calibrated, sensors with a frequency
output but I already had specified two A/D channels.

   - Tom

At 01:04 PM 2/6/98 -0500, you wrote:
>On Fri, 6 Feb 1998 07:40:51 -0800 Tom Handley <thandley@TELEPORT.COM>
>writes:
>
>>   The HyCal sensor is similar to many others in that a change in
>>humidity
>>causes a change in capacitance which changes the frequency of an
>>oscillator.
>>This is converted to a voltage and is linear.
>
>Can you get a sample of the oscillator frequency out of the sensor?  It
>is simple to count with a PIC, much harder to deal with analog.  You'd
>need calibration data in terms of frequency too.
>
>
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