I think that RH sensors for VCRs can be bought as spare parts. Try a local
VCR repair shop. I do not know what range they have, and they are
guaranteed not to be linear, but at least there is one in each and every
vcr, dat tape, and camcorder (even dv), so there should be spare parts...

The only time I played with this I found that they go high Z when humid
(esp. condensation). I suppose that one could be calibrated. Standard
circuit seems to be 220-330K pullup from 5V followed by simple comparator
or A/D measurement.

For a single, strip a dead VCR and look in the schematics for the exact
value of the pullup resistor. I suspect that a lower resistor value will
not do it much good.

Since these go bad once in a while, it is a good idea not to rely on them
too much imho.

Peter

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