Humidity sensor interface ideas

[Tony]

Hello
I am looking for a way to make a humidistat using the discrete resistive or
capacitive ceramic sensors. I need little accuracy. They require an ac bias
with about 100mv max. I want to make it a low parts count design. I do not
want to use the modules that condition the signals because the cost is too
high. I would like to use the comparator in a micro for instance. 10%
accuracy is ok.
Thanks for any info.
Tony

 

[Jeroen Vriesman]

If you use the 2322 691 90001 sensor from bc components,
http://www.bccomponents.com/ and a 556, one half of it oscillating, the
other half a one-shot triggered by the oscillator, and then a low-pass
filter, you have an output voltage.

1 sensor, 2 caps, 3 resistors, 1x 556. that's 7 components.